Normálně je pole souborem podobného typu prvků, které mají souvislé umístění v paměti.
Java pole je objekt, který obsahuje prvky podobného datového typu. Prvky pole jsou navíc uloženy v souvislém paměťovém místě. Jde o datovou strukturu, kde ukládáme podobné prvky. V poli Java můžeme uložit pouze pevnou sadu prvků.
Pole v Javě je založeno na indexu, první prvek pole je uložen na 0. indexu, 2. prvek je uložen na 1. indexu a tak dále.
Na rozdíl od C/C++ můžeme délku pole získat pomocí členu length. V C/C++ musíme použít operátor sizeof.
V Javě je pole objekt dynamicky generované třídy. Pole Java dědí třídu Object a implementuje rozhraní Serializable i Cloneable. V Javě můžeme uložit primitivní hodnoty nebo objekty do pole. Stejně jako C/C++ můžeme také v Javě vytvářet jednorozměrná nebo vícerozměrná pole.
Navíc Java poskytuje funkci anonymních polí, která není dostupná v C/C++.
Výhody
Nevýhody
Typy pole v Javě
Existují dva typy pole.
- Jednorozměrné pole
- Vícerozměrné pole
Jednorozměrné pole v Javě
Syntaxe pro deklaraci pole v Javě
vstup java
dataType[] arr; (or) dataType []arr; (or) dataType arr[];
Instanciace pole v Javě
arrayRefVar=new datatype[size];
Příklad Java Array
Podívejme se na jednoduchý příklad java pole, kde budeme deklarovat, instanciovat, inicializovat a procházet pole.
//Java Program to illustrate how to declare, instantiate, initialize //and traverse the Java array. class Testarray{ public static void main(String args[]){ int a[]=new int[5];//declaration and instantiation a[0]=10;//initialization a[1]=20; a[2]=70; a[3]=40; a[4]=50; //traversing array for(int i=0;i <a.length;i++) length is the property of array system.out.println(a[i]); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 10 20 70 40 50 </pre> <hr> <h2>Declaration, Instantiation and Initialization of Java Array</h2> <p>We can declare, instantiate and initialize the java array together by:</p> <pre> int a[]={33,3,4,5};//declaration, instantiation and initialization </pre> <p>Let's see the simple example to print this array.</p> <pre> //Java Program to illustrate the use of declaration, instantiation //and initialization of Java array in a single line class Testarray1{ public static void main(String args[]){ int a[]={33,3,4,5};//declaration, instantiation and initialization //printing array for(int i=0;i <a.length;i++) length is the property of array system.out.println(a[i]); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 33 3 4 5 </pre> <h2>For-each Loop for Java Array</h2> <p>We can also print the Java array using <strong> <a href="/java-each-loop-enhanced">for-each loop</a> </strong> . The Java for-each loop prints the array elements one by one. It holds an array element in a variable, then executes the body of the loop.</p> <p>The syntax of the for-each loop is given below:</p> <pre> for(data_type variable:array){ //body of the loop } </pre> <p>Let us see the example of print the elements of Java array using the for-each loop.</p> <pre> //Java Program to print the array elements using for-each loop class Testarray1{ public static void main(String args[]){ int arr[]={33,3,4,5}; //printing array using for-each loop for(int i:arr) System.out.println(i); }} </pre> <p>Output:</p> <pre> 33 3 4 5 </pre> <hr> <h2>Passing Array to a Method in Java</h2> <p>We can pass the java array to method so that we can reuse the same logic on any array.</p> <p>Let's see the simple example to get the minimum number of an array using a method.</p> <pre> //Java Program to demonstrate the way of passing an array //to method. class Testarray2{ //creating a method which receives an array as a parameter static void min(int arr[]){ int min=arr[0]; for(int i=1;iarr[i]) min=arr[i]; System.out.println(min); } public static void main(String args[]){ int a[]={33,3,4,5};//declaring and initializing an array min(a);//passing array to method }} </pre> <span> Test it Now </span> <p>Output:</p> <pre> 3 </pre> <h2>Anonymous Array in Java</h2> <p>Java supports the feature of an anonymous array, so you don't need to declare the array while passing an array to the method.</p> <pre> //Java Program to demonstrate the way of passing an anonymous array //to method. public class TestAnonymousArray{ //creating a method which receives an array as a parameter static void printArray(int arr[]){ for(int i=0;i <arr.length;i++) system.out.println(arr[i]); } public static void main(string args[]){ printarray(new int[]{10,22,44,66}); passing anonymous array to method }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 10 22 44 66 </pre> <h2>Returning Array from the Method</h2> <p>We can also return an array from the method in Java.</p> <pre> //Java Program to return an array from the method class TestReturnArray{ //creating method which returns an array static int[] get(){ return new int[]{10,30,50,90,60}; } public static void main(String args[]){ //calling method which returns an array int arr[]=get(); //printing the values of an array for(int i=0;i <arr.length;i++) system.out.println(arr[i]); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 10 30 50 90 60 </pre> <h2>ArrayIndexOutOfBoundsException</h2> <p>The Java Virtual Machine (JVM) throws an ArrayIndexOutOfBoundsException if length of the array in negative, equal to the array size or greater than the array size while traversing the array.</p> <pre> //Java Program to demonstrate the case of //ArrayIndexOutOfBoundsException in a Java Array. public class TestArrayException{ public static void main(String args[]){ int arr[]={50,60,70,80}; for(int i=0;i<=arr.length;i++){ system.out.println(arr[i]); } }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> Exception in thread 'main' java.lang.ArrayIndexOutOfBoundsException: 4 at TestArrayException.main(TestArrayException.java:5) 50 60 70 80 </pre> <hr> <h2>Multidimensional Array in Java</h2> <p>In such case, data is stored in row and column based index (also known as matrix form).</p> <p> <strong>Syntax to Declare Multidimensional Array in Java</strong> </p> <pre> dataType[][] arrayRefVar; (or) dataType [][]arrayRefVar; (or) dataType arrayRefVar[][]; (or) dataType []arrayRefVar[]; </pre> <p> <strong>Example to instantiate Multidimensional Array in Java</strong> </p> <pre> int[][] arr=new int[3][3];//3 row and 3 column </pre> <p> <strong>Example to initialize Multidimensional Array in Java</strong> </p> <pre> arr[0][0]=1; arr[0][1]=2; arr[0][2]=3; arr[1][0]=4; arr[1][1]=5; arr[1][2]=6; arr[2][0]=7; arr[2][1]=8; arr[2][2]=9; </pre> <h3>Example of Multidimensional Java Array</h3> <p>Let's see the simple example to declare, instantiate, initialize and print the 2Dimensional array.</p> <pre> //Java Program to illustrate the use of multidimensional array class Testarray3{ public static void main(String args[]){ //declaring and initializing 2D array int arr[][]={{1,2,3},{2,4,5},{4,4,5}}; //printing 2D array for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" system.out.print(arr[i][j]+' '); } system.out.println(); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 1 2 3 2 4 5 4 4 5 </pre> <h2>Jagged Array in Java</h2> <p>If we are creating odd number of columns in a 2D array, it is known as a jagged array. In other words, it is an array of arrays with different number of columns.</p> <pre> //Java Program to illustrate the jagged array class TestJaggedArray{ public static void main(String[] args){ //declaring a 2D array with odd columns int arr[][] = new int[3][]; arr[0] = new int[3]; arr[1] = new int[4]; arr[2] = new int[2]; //initializing a jagged array int count = 0; for (int i=0; i <arr.length; i++) for(int j="0;" <arr[i].length; j++) arr[i][j]="count++;" printing the data of a jagged array for (int i="0;" <arr.length; i++){ j++){ system.out.print(arr[i][j]+' '); } system.out.println(); new line < pre> <span> Test it Now </span> <p>Output:</p> <pre> 0 1 2 3 4 5 6 7 8 </pre> <hr> <h2>What is the class name of Java array?</h2> <p>In Java, an array is an object. For array object, a proxy class is created whose name can be obtained by getClass().getName() method on the object.</p> <pre> //Java Program to get the class name of array in Java class Testarray4{ public static void main(String args[]){ //declaration and initialization of array int arr[]={4,4,5}; //getting the class name of Java array Class c=arr.getClass(); String name=c.getName(); //printing the class name of Java array System.out.println(name); }} </pre> <span> Test it Now </span> <p>Output:</p> <pre> I </pre> <hr> <h2>Copying a Java Array</h2> <p>We can copy an array to another by the arraycopy() method of System class.</p> <p> <strong>Syntax of arraycopy method</strong> </p> <pre> public static void arraycopy( Object src, int srcPos,Object dest, int destPos, int length ) </pre> <h3>Example of Copying an Array in Java</h3> <pre> //Java Program to copy a source array into a destination array in Java class TestArrayCopyDemo { public static void main(String[] args) { //declaring a source array char[] copyFrom = { 'd', 'e', 'c', 'a', 'f', 'f', 'e', 'i', 'n', 'a', 't', 'e', 'd' }; //declaring a destination array char[] copyTo = new char[7]; //copying array using System.arraycopy() method System.arraycopy(copyFrom, 2, copyTo, 0, 7); //printing the destination array System.out.println(String.valueOf(copyTo)); } } </pre> <span> Test it Now </span> <p>Output:</p> <pre> caffein </pre> <hr> <h2>Cloning an Array in Java</h2> <p>Since, Java array implements the Cloneable interface, we can create the clone of the Java array. If we create the clone of a single-dimensional array, it creates the deep copy of the Java array. It means, it will copy the actual value. But, if we create the clone of a multidimensional array, it creates the shallow copy of the Java array which means it copies the references.</p> <pre> //Java Program to clone the array class Testarray1{ public static void main(String args[]){ int arr[]={33,3,4,5}; System.out.println('Printing original array:'); for(int i:arr) System.out.println(i); System.out.println('Printing clone of the array:'); int carr[]=arr.clone(); for(int i:carr) System.out.println(i); System.out.println('Are both equal?'); System.out.println(arr==carr); }} </pre> <p>Output:</p> <pre> Printing original array: 33 3 4 5 Printing clone of the array: 33 3 4 5 Are both equal? false </pre> <h2>Addition of 2 Matrices in Java</h2> <p>Let's see a simple example that adds two matrices.</p> <pre> //Java Program to demonstrate the addition of two matrices in Java class Testarray5{ public static void main(String args[]){ //creating two matrices int a[][]={{1,3,4},{3,4,5}}; int b[][]={{1,3,4},{3,4,5}}; //creating another matrix to store the sum of two matrices int c[][]=new int[2][3]; //adding and printing addition of 2 matrices for(int i=0;i<2;i++){ for(int j="0;j<3;j++){" c[i][j]="a[i][j]+b[i][j];" system.out.print(c[i][j]+' '); } system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 2 6 8 6 8 10 </pre> <h2>Multiplication of 2 Matrices in Java</h2> <p>In the case of matrix multiplication, a one-row element of the first matrix is multiplied by all the columns of the second matrix which can be understood by the image given below.</p> <img src="//techcodeview.com/img/java-object-class/39/java-arrays.webp" alt="Matrix Multiplication in Java"> <p>Let's see a simple example to multiply two matrices of 3 rows and 3 columns.</p> <pre> //Java Program to multiply two matrices public class MatrixMultiplicationExample{ public static void main(String args[]){ //creating two matrices int a[][]={{1,1,1},{2,2,2},{3,3,3}}; int b[][]={{1,1,1},{2,2,2},{3,3,3}}; //creating another matrix to store the multiplication of two matrices int c[][]=new int[3][3]; //3 rows and 3 columns //multiplying and printing multiplication of 2 matrices for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" c[i][j]="0;" k="0;k<3;k++)" { c[i][j]+="a[i][k]*b[k][j];" } end of loop system.out.print(c[i][j]+' '); printing matrix element system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 6 6 6 12 12 12 18 18 18 </pre> <h3>Related Topics</h3> <h2> 1) Java Program to copy all elements of one array into another array </h2> <h2> 2) Java Program to find the frequency of each element in the array </h2> <h2> 3) Java Program to left rotate the elements of an array </h2> <h2> 4) Java Program to print the duplicate elements of an array </h2> <h2> 5) Java Program to print the elements of an array </h2> <h2> 6) Java Program to print the elements of an array in reverse order </h2> <h2> 7) Java Program to print the elements of an array present on even position </h2> <h2> 8) Java Program to print the elements of an array present on odd position </h2> <h2> 9) Java Program to print the largest element in an array </h2> <h2> 10) Java Program to print the smallest element in an array </h2> <h2> 11) Java Program to print the number of elements present in an array </h2> <h2> 12) Java Program to print the sum of all the items of the array </h2> <h2> 13) Java Program to right rotate the elements of an array </h2> <h2> 14) Java Program to sort the elements of an array in ascending order </h2> <h2> 15) Java Program to sort the elements of an array in descending order </h2> <h2>16) Find 3rd Largest Number in an Array </h2> <h2>17) Find 2nd Largest Number in an Array </h2> <h2>18) Find Largest Number in an Array </h2> <h2>19) Find 2nd Smallest Number in an Array </h2> <h2>20) Find Smallest Number in an Array </h2> <h2>21) Remove Duplicate Element in an Array </h2> <h2>22) Add Two Matrices </h2> <h2>23) <a href="/java-program-multiply-two-matrices">Multiply Two Matrices</a> </h2> <h2>24) Print Odd and Even Number from an Array </h2> <h2>25) Transpose matrix </h2> <h2> 26) Java Program to subtract the two matrices </h2> <h2> 27) Java Program to determine whether a given matrix is an identity matrix </h2> <h2> 28) Java Program to determine whether a given matrix is a sparse matrix </h2> <h2> 29) Java Program to determine whether two matrices are equal </h2> <h2> 30) Java Program to display the lower triangular matrix </h2> <h2> 31) Java Program to display the upper triangular matrix </h2> <h2> 32) Java Program to find the frequency of odd & even numbers in the given matrix </h2> <h2> 33) Java Program to find the product of two matrices </h2> <h2> 34) Java Program to find the sum of each row and each column of a matrix </h2> <h2> 35) Java Program to find the transpose of a given matrix </h2></3;i++){></pre></2;i++){></pre></arr.length;></pre></3;i++){></pre></=arr.length;i++){></pre></arr.length;i++)></pre></arr.length;i++)></pre></a.length;i++)></pre></a.length;i++)> Deklarace, instanciace a inicializace Java Array
Můžeme deklarovat, vytvořit instanci a inicializovat pole java společně pomocí:
int a[]={33,3,4,5};//declaration, instantiation and initialization Podívejme se na jednoduchý příklad tisku tohoto pole.
//Java Program to illustrate the use of declaration, instantiation //and initialization of Java array in a single line class Testarray1{ public static void main(String args[]){ int a[]={33,3,4,5};//declaration, instantiation and initialization //printing array for(int i=0;i <a.length;i++) length is the property of array system.out.println(a[i]); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 33 3 4 5 </pre> <h2>For-each Loop for Java Array</h2> <p>We can also print the Java array using <strong> <a href="/java-each-loop-enhanced">for-each loop</a> </strong> . The Java for-each loop prints the array elements one by one. It holds an array element in a variable, then executes the body of the loop.</p> <p>The syntax of the for-each loop is given below:</p> <pre> for(data_type variable:array){ //body of the loop } </pre> <p>Let us see the example of print the elements of Java array using the for-each loop.</p> <pre> //Java Program to print the array elements using for-each loop class Testarray1{ public static void main(String args[]){ int arr[]={33,3,4,5}; //printing array using for-each loop for(int i:arr) System.out.println(i); }} </pre> <p>Output:</p> <pre> 33 3 4 5 </pre> <hr> <h2>Passing Array to a Method in Java</h2> <p>We can pass the java array to method so that we can reuse the same logic on any array.</p> <p>Let's see the simple example to get the minimum number of an array using a method.</p> <pre> //Java Program to demonstrate the way of passing an array //to method. class Testarray2{ //creating a method which receives an array as a parameter static void min(int arr[]){ int min=arr[0]; for(int i=1;iarr[i]) min=arr[i]; System.out.println(min); } public static void main(String args[]){ int a[]={33,3,4,5};//declaring and initializing an array min(a);//passing array to method }} </pre> <span> Test it Now </span> <p>Output:</p> <pre> 3 </pre> <h2>Anonymous Array in Java</h2> <p>Java supports the feature of an anonymous array, so you don't need to declare the array while passing an array to the method.</p> <pre> //Java Program to demonstrate the way of passing an anonymous array //to method. public class TestAnonymousArray{ //creating a method which receives an array as a parameter static void printArray(int arr[]){ for(int i=0;i <arr.length;i++) system.out.println(arr[i]); } public static void main(string args[]){ printarray(new int[]{10,22,44,66}); passing anonymous array to method }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 10 22 44 66 </pre> <h2>Returning Array from the Method</h2> <p>We can also return an array from the method in Java.</p> <pre> //Java Program to return an array from the method class TestReturnArray{ //creating method which returns an array static int[] get(){ return new int[]{10,30,50,90,60}; } public static void main(String args[]){ //calling method which returns an array int arr[]=get(); //printing the values of an array for(int i=0;i <arr.length;i++) system.out.println(arr[i]); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 10 30 50 90 60 </pre> <h2>ArrayIndexOutOfBoundsException</h2> <p>The Java Virtual Machine (JVM) throws an ArrayIndexOutOfBoundsException if length of the array in negative, equal to the array size or greater than the array size while traversing the array.</p> <pre> //Java Program to demonstrate the case of //ArrayIndexOutOfBoundsException in a Java Array. public class TestArrayException{ public static void main(String args[]){ int arr[]={50,60,70,80}; for(int i=0;i<=arr.length;i++){ system.out.println(arr[i]); } }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> Exception in thread 'main' java.lang.ArrayIndexOutOfBoundsException: 4 at TestArrayException.main(TestArrayException.java:5) 50 60 70 80 </pre> <hr> <h2>Multidimensional Array in Java</h2> <p>In such case, data is stored in row and column based index (also known as matrix form).</p> <p> <strong>Syntax to Declare Multidimensional Array in Java</strong> </p> <pre> dataType[][] arrayRefVar; (or) dataType [][]arrayRefVar; (or) dataType arrayRefVar[][]; (or) dataType []arrayRefVar[]; </pre> <p> <strong>Example to instantiate Multidimensional Array in Java</strong> </p> <pre> int[][] arr=new int[3][3];//3 row and 3 column </pre> <p> <strong>Example to initialize Multidimensional Array in Java</strong> </p> <pre> arr[0][0]=1; arr[0][1]=2; arr[0][2]=3; arr[1][0]=4; arr[1][1]=5; arr[1][2]=6; arr[2][0]=7; arr[2][1]=8; arr[2][2]=9; </pre> <h3>Example of Multidimensional Java Array</h3> <p>Let's see the simple example to declare, instantiate, initialize and print the 2Dimensional array.</p> <pre> //Java Program to illustrate the use of multidimensional array class Testarray3{ public static void main(String args[]){ //declaring and initializing 2D array int arr[][]={{1,2,3},{2,4,5},{4,4,5}}; //printing 2D array for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" system.out.print(arr[i][j]+\' \'); } system.out.println(); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 1 2 3 2 4 5 4 4 5 </pre> <h2>Jagged Array in Java</h2> <p>If we are creating odd number of columns in a 2D array, it is known as a jagged array. In other words, it is an array of arrays with different number of columns.</p> <pre> //Java Program to illustrate the jagged array class TestJaggedArray{ public static void main(String[] args){ //declaring a 2D array with odd columns int arr[][] = new int[3][]; arr[0] = new int[3]; arr[1] = new int[4]; arr[2] = new int[2]; //initializing a jagged array int count = 0; for (int i=0; i <arr.length; i++) for(int j="0;" <arr[i].length; j++) arr[i][j]="count++;" printing the data of a jagged array for (int i="0;" <arr.length; i++){ j++){ system.out.print(arr[i][j]+\' \'); } system.out.println(); new line < pre> <span> Test it Now </span> <p>Output:</p> <pre> 0 1 2 3 4 5 6 7 8 </pre> <hr> <h2>What is the class name of Java array?</h2> <p>In Java, an array is an object. For array object, a proxy class is created whose name can be obtained by getClass().getName() method on the object.</p> <pre> //Java Program to get the class name of array in Java class Testarray4{ public static void main(String args[]){ //declaration and initialization of array int arr[]={4,4,5}; //getting the class name of Java array Class c=arr.getClass(); String name=c.getName(); //printing the class name of Java array System.out.println(name); }} </pre> <span> Test it Now </span> <p>Output:</p> <pre> I </pre> <hr> <h2>Copying a Java Array</h2> <p>We can copy an array to another by the arraycopy() method of System class.</p> <p> <strong>Syntax of arraycopy method</strong> </p> <pre> public static void arraycopy( Object src, int srcPos,Object dest, int destPos, int length ) </pre> <h3>Example of Copying an Array in Java</h3> <pre> //Java Program to copy a source array into a destination array in Java class TestArrayCopyDemo { public static void main(String[] args) { //declaring a source array char[] copyFrom = { 'd', 'e', 'c', 'a', 'f', 'f', 'e', 'i', 'n', 'a', 't', 'e', 'd' }; //declaring a destination array char[] copyTo = new char[7]; //copying array using System.arraycopy() method System.arraycopy(copyFrom, 2, copyTo, 0, 7); //printing the destination array System.out.println(String.valueOf(copyTo)); } } </pre> <span> Test it Now </span> <p>Output:</p> <pre> caffein </pre> <hr> <h2>Cloning an Array in Java</h2> <p>Since, Java array implements the Cloneable interface, we can create the clone of the Java array. If we create the clone of a single-dimensional array, it creates the deep copy of the Java array. It means, it will copy the actual value. But, if we create the clone of a multidimensional array, it creates the shallow copy of the Java array which means it copies the references.</p> <pre> //Java Program to clone the array class Testarray1{ public static void main(String args[]){ int arr[]={33,3,4,5}; System.out.println('Printing original array:'); for(int i:arr) System.out.println(i); System.out.println('Printing clone of the array:'); int carr[]=arr.clone(); for(int i:carr) System.out.println(i); System.out.println('Are both equal?'); System.out.println(arr==carr); }} </pre> <p>Output:</p> <pre> Printing original array: 33 3 4 5 Printing clone of the array: 33 3 4 5 Are both equal? false </pre> <h2>Addition of 2 Matrices in Java</h2> <p>Let's see a simple example that adds two matrices.</p> <pre> //Java Program to demonstrate the addition of two matrices in Java class Testarray5{ public static void main(String args[]){ //creating two matrices int a[][]={{1,3,4},{3,4,5}}; int b[][]={{1,3,4},{3,4,5}}; //creating another matrix to store the sum of two matrices int c[][]=new int[2][3]; //adding and printing addition of 2 matrices for(int i=0;i<2;i++){ for(int j="0;j<3;j++){" c[i][j]="a[i][j]+b[i][j];" system.out.print(c[i][j]+\' \'); } system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 2 6 8 6 8 10 </pre> <h2>Multiplication of 2 Matrices in Java</h2> <p>In the case of matrix multiplication, a one-row element of the first matrix is multiplied by all the columns of the second matrix which can be understood by the image given below.</p> <img src="//techcodeview.com/img/java-object-class/39/java-arrays.webp" alt="Matrix Multiplication in Java"> <p>Let's see a simple example to multiply two matrices of 3 rows and 3 columns.</p> <pre> //Java Program to multiply two matrices public class MatrixMultiplicationExample{ public static void main(String args[]){ //creating two matrices int a[][]={{1,1,1},{2,2,2},{3,3,3}}; int b[][]={{1,1,1},{2,2,2},{3,3,3}}; //creating another matrix to store the multiplication of two matrices int c[][]=new int[3][3]; //3 rows and 3 columns //multiplying and printing multiplication of 2 matrices for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" c[i][j]="0;" k="0;k<3;k++)" { c[i][j]+="a[i][k]*b[k][j];" } end of loop system.out.print(c[i][j]+\' \'); printing matrix element system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 6 6 6 12 12 12 18 18 18 </pre> <h3>Related Topics</h3> <h2> 1) Java Program to copy all elements of one array into another array </h2> <h2> 2) Java Program to find the frequency of each element in the array </h2> <h2> 3) Java Program to left rotate the elements of an array </h2> <h2> 4) Java Program to print the duplicate elements of an array </h2> <h2> 5) Java Program to print the elements of an array </h2> <h2> 6) Java Program to print the elements of an array in reverse order </h2> <h2> 7) Java Program to print the elements of an array present on even position </h2> <h2> 8) Java Program to print the elements of an array present on odd position </h2> <h2> 9) Java Program to print the largest element in an array </h2> <h2> 10) Java Program to print the smallest element in an array </h2> <h2> 11) Java Program to print the number of elements present in an array </h2> <h2> 12) Java Program to print the sum of all the items of the array </h2> <h2> 13) Java Program to right rotate the elements of an array </h2> <h2> 14) Java Program to sort the elements of an array in ascending order </h2> <h2> 15) Java Program to sort the elements of an array in descending order </h2> <h2>16) Find 3rd Largest Number in an Array </h2> <h2>17) Find 2nd Largest Number in an Array </h2> <h2>18) Find Largest Number in an Array </h2> <h2>19) Find 2nd Smallest Number in an Array </h2> <h2>20) Find Smallest Number in an Array </h2> <h2>21) Remove Duplicate Element in an Array </h2> <h2>22) Add Two Matrices </h2> <h2>23) <a href="/java-program-multiply-two-matrices">Multiply Two Matrices</a> </h2> <h2>24) Print Odd and Even Number from an Array </h2> <h2>25) Transpose matrix </h2> <h2> 26) Java Program to subtract the two matrices </h2> <h2> 27) Java Program to determine whether a given matrix is an identity matrix </h2> <h2> 28) Java Program to determine whether a given matrix is a sparse matrix </h2> <h2> 29) Java Program to determine whether two matrices are equal </h2> <h2> 30) Java Program to display the lower triangular matrix </h2> <h2> 31) Java Program to display the upper triangular matrix </h2> <h2> 32) Java Program to find the frequency of odd & even numbers in the given matrix </h2> <h2> 33) Java Program to find the product of two matrices </h2> <h2> 34) Java Program to find the sum of each row and each column of a matrix </h2> <h2> 35) Java Program to find the transpose of a given matrix </h2></3;i++){></pre></2;i++){></pre></arr.length;></pre></3;i++){></pre></=arr.length;i++){></pre></arr.length;i++)></pre></arr.length;i++)></pre></a.length;i++)> Pro každou smyčku pro pole Java
Pole Java můžeme také vytisknout pomocí pro každou smyčku . Smyčka Java for-each vytiskne prvky pole jeden po druhém. Obsahuje prvek pole v proměnné a poté provede tělo smyčky.
Syntaxe smyčky for-each je uvedena níže:
for(data_type variable:array){ //body of the loop } Podívejme se na příklad tisku prvků pole Java pomocí cyklu for-each.
//Java Program to print the array elements using for-each loop class Testarray1{ public static void main(String args[]){ int arr[]={33,3,4,5}; //printing array using for-each loop for(int i:arr) System.out.println(i); }} Výstup:
33 3 4 5
Předání pole metodě v Javě
Pole java můžeme předat metodě, abychom mohli znovu použít stejnou logiku na libovolném poli.
Podívejme se na jednoduchý příklad, jak pomocí metody získat minimální počet pole.
//Java Program to demonstrate the way of passing an array //to method. class Testarray2{ //creating a method which receives an array as a parameter static void min(int arr[]){ int min=arr[0]; for(int i=1;iarr[i]) min=arr[i]; System.out.println(min); } public static void main(String args[]){ int a[]={33,3,4,5};//declaring and initializing an array min(a);//passing array to method }} Otestujte to hned Výstup:
3
Anonymní pole v Javě
Java podporuje funkci anonymního pole, takže při předávání pole metodě nemusíte pole deklarovat.
//Java Program to demonstrate the way of passing an anonymous array //to method. public class TestAnonymousArray{ //creating a method which receives an array as a parameter static void printArray(int arr[]){ for(int i=0;i <arr.length;i++) system.out.println(arr[i]); } public static void main(string args[]){ printarray(new int[]{10,22,44,66}); passing anonymous array to method }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 10 22 44 66 </pre> <h2>Returning Array from the Method</h2> <p>We can also return an array from the method in Java.</p> <pre> //Java Program to return an array from the method class TestReturnArray{ //creating method which returns an array static int[] get(){ return new int[]{10,30,50,90,60}; } public static void main(String args[]){ //calling method which returns an array int arr[]=get(); //printing the values of an array for(int i=0;i <arr.length;i++) system.out.println(arr[i]); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 10 30 50 90 60 </pre> <h2>ArrayIndexOutOfBoundsException</h2> <p>The Java Virtual Machine (JVM) throws an ArrayIndexOutOfBoundsException if length of the array in negative, equal to the array size or greater than the array size while traversing the array.</p> <pre> //Java Program to demonstrate the case of //ArrayIndexOutOfBoundsException in a Java Array. public class TestArrayException{ public static void main(String args[]){ int arr[]={50,60,70,80}; for(int i=0;i<=arr.length;i++){ system.out.println(arr[i]); } }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> Exception in thread 'main' java.lang.ArrayIndexOutOfBoundsException: 4 at TestArrayException.main(TestArrayException.java:5) 50 60 70 80 </pre> <hr> <h2>Multidimensional Array in Java</h2> <p>In such case, data is stored in row and column based index (also known as matrix form).</p> <p> <strong>Syntax to Declare Multidimensional Array in Java</strong> </p> <pre> dataType[][] arrayRefVar; (or) dataType [][]arrayRefVar; (or) dataType arrayRefVar[][]; (or) dataType []arrayRefVar[]; </pre> <p> <strong>Example to instantiate Multidimensional Array in Java</strong> </p> <pre> int[][] arr=new int[3][3];//3 row and 3 column </pre> <p> <strong>Example to initialize Multidimensional Array in Java</strong> </p> <pre> arr[0][0]=1; arr[0][1]=2; arr[0][2]=3; arr[1][0]=4; arr[1][1]=5; arr[1][2]=6; arr[2][0]=7; arr[2][1]=8; arr[2][2]=9; </pre> <h3>Example of Multidimensional Java Array</h3> <p>Let's see the simple example to declare, instantiate, initialize and print the 2Dimensional array.</p> <pre> //Java Program to illustrate the use of multidimensional array class Testarray3{ public static void main(String args[]){ //declaring and initializing 2D array int arr[][]={{1,2,3},{2,4,5},{4,4,5}}; //printing 2D array for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" system.out.print(arr[i][j]+\' \'); } system.out.println(); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 1 2 3 2 4 5 4 4 5 </pre> <h2>Jagged Array in Java</h2> <p>If we are creating odd number of columns in a 2D array, it is known as a jagged array. In other words, it is an array of arrays with different number of columns.</p> <pre> //Java Program to illustrate the jagged array class TestJaggedArray{ public static void main(String[] args){ //declaring a 2D array with odd columns int arr[][] = new int[3][]; arr[0] = new int[3]; arr[1] = new int[4]; arr[2] = new int[2]; //initializing a jagged array int count = 0; for (int i=0; i <arr.length; i++) for(int j="0;" <arr[i].length; j++) arr[i][j]="count++;" printing the data of a jagged array for (int i="0;" <arr.length; i++){ j++){ system.out.print(arr[i][j]+\' \'); } system.out.println(); new line < pre> <span> Test it Now </span> <p>Output:</p> <pre> 0 1 2 3 4 5 6 7 8 </pre> <hr> <h2>What is the class name of Java array?</h2> <p>In Java, an array is an object. For array object, a proxy class is created whose name can be obtained by getClass().getName() method on the object.</p> <pre> //Java Program to get the class name of array in Java class Testarray4{ public static void main(String args[]){ //declaration and initialization of array int arr[]={4,4,5}; //getting the class name of Java array Class c=arr.getClass(); String name=c.getName(); //printing the class name of Java array System.out.println(name); }} </pre> <span> Test it Now </span> <p>Output:</p> <pre> I </pre> <hr> <h2>Copying a Java Array</h2> <p>We can copy an array to another by the arraycopy() method of System class.</p> <p> <strong>Syntax of arraycopy method</strong> </p> <pre> public static void arraycopy( Object src, int srcPos,Object dest, int destPos, int length ) </pre> <h3>Example of Copying an Array in Java</h3> <pre> //Java Program to copy a source array into a destination array in Java class TestArrayCopyDemo { public static void main(String[] args) { //declaring a source array char[] copyFrom = { 'd', 'e', 'c', 'a', 'f', 'f', 'e', 'i', 'n', 'a', 't', 'e', 'd' }; //declaring a destination array char[] copyTo = new char[7]; //copying array using System.arraycopy() method System.arraycopy(copyFrom, 2, copyTo, 0, 7); //printing the destination array System.out.println(String.valueOf(copyTo)); } } </pre> <span> Test it Now </span> <p>Output:</p> <pre> caffein </pre> <hr> <h2>Cloning an Array in Java</h2> <p>Since, Java array implements the Cloneable interface, we can create the clone of the Java array. If we create the clone of a single-dimensional array, it creates the deep copy of the Java array. It means, it will copy the actual value. But, if we create the clone of a multidimensional array, it creates the shallow copy of the Java array which means it copies the references.</p> <pre> //Java Program to clone the array class Testarray1{ public static void main(String args[]){ int arr[]={33,3,4,5}; System.out.println('Printing original array:'); for(int i:arr) System.out.println(i); System.out.println('Printing clone of the array:'); int carr[]=arr.clone(); for(int i:carr) System.out.println(i); System.out.println('Are both equal?'); System.out.println(arr==carr); }} </pre> <p>Output:</p> <pre> Printing original array: 33 3 4 5 Printing clone of the array: 33 3 4 5 Are both equal? false </pre> <h2>Addition of 2 Matrices in Java</h2> <p>Let's see a simple example that adds two matrices.</p> <pre> //Java Program to demonstrate the addition of two matrices in Java class Testarray5{ public static void main(String args[]){ //creating two matrices int a[][]={{1,3,4},{3,4,5}}; int b[][]={{1,3,4},{3,4,5}}; //creating another matrix to store the sum of two matrices int c[][]=new int[2][3]; //adding and printing addition of 2 matrices for(int i=0;i<2;i++){ for(int j="0;j<3;j++){" c[i][j]="a[i][j]+b[i][j];" system.out.print(c[i][j]+\' \'); } system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 2 6 8 6 8 10 </pre> <h2>Multiplication of 2 Matrices in Java</h2> <p>In the case of matrix multiplication, a one-row element of the first matrix is multiplied by all the columns of the second matrix which can be understood by the image given below.</p> <img src="//techcodeview.com/img/java-object-class/39/java-arrays.webp" alt="Matrix Multiplication in Java"> <p>Let's see a simple example to multiply two matrices of 3 rows and 3 columns.</p> <pre> //Java Program to multiply two matrices public class MatrixMultiplicationExample{ public static void main(String args[]){ //creating two matrices int a[][]={{1,1,1},{2,2,2},{3,3,3}}; int b[][]={{1,1,1},{2,2,2},{3,3,3}}; //creating another matrix to store the multiplication of two matrices int c[][]=new int[3][3]; //3 rows and 3 columns //multiplying and printing multiplication of 2 matrices for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" c[i][j]="0;" k="0;k<3;k++)" { c[i][j]+="a[i][k]*b[k][j];" } end of loop system.out.print(c[i][j]+\' \'); printing matrix element system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 6 6 6 12 12 12 18 18 18 </pre> <h3>Related Topics</h3> <h2> 1) Java Program to copy all elements of one array into another array </h2> <h2> 2) Java Program to find the frequency of each element in the array </h2> <h2> 3) Java Program to left rotate the elements of an array </h2> <h2> 4) Java Program to print the duplicate elements of an array </h2> <h2> 5) Java Program to print the elements of an array </h2> <h2> 6) Java Program to print the elements of an array in reverse order </h2> <h2> 7) Java Program to print the elements of an array present on even position </h2> <h2> 8) Java Program to print the elements of an array present on odd position </h2> <h2> 9) Java Program to print the largest element in an array </h2> <h2> 10) Java Program to print the smallest element in an array </h2> <h2> 11) Java Program to print the number of elements present in an array </h2> <h2> 12) Java Program to print the sum of all the items of the array </h2> <h2> 13) Java Program to right rotate the elements of an array </h2> <h2> 14) Java Program to sort the elements of an array in ascending order </h2> <h2> 15) Java Program to sort the elements of an array in descending order </h2> <h2>16) Find 3rd Largest Number in an Array </h2> <h2>17) Find 2nd Largest Number in an Array </h2> <h2>18) Find Largest Number in an Array </h2> <h2>19) Find 2nd Smallest Number in an Array </h2> <h2>20) Find Smallest Number in an Array </h2> <h2>21) Remove Duplicate Element in an Array </h2> <h2>22) Add Two Matrices </h2> <h2>23) <a href="/java-program-multiply-two-matrices">Multiply Two Matrices</a> </h2> <h2>24) Print Odd and Even Number from an Array </h2> <h2>25) Transpose matrix </h2> <h2> 26) Java Program to subtract the two matrices </h2> <h2> 27) Java Program to determine whether a given matrix is an identity matrix </h2> <h2> 28) Java Program to determine whether a given matrix is a sparse matrix </h2> <h2> 29) Java Program to determine whether two matrices are equal </h2> <h2> 30) Java Program to display the lower triangular matrix </h2> <h2> 31) Java Program to display the upper triangular matrix </h2> <h2> 32) Java Program to find the frequency of odd & even numbers in the given matrix </h2> <h2> 33) Java Program to find the product of two matrices </h2> <h2> 34) Java Program to find the sum of each row and each column of a matrix </h2> <h2> 35) Java Program to find the transpose of a given matrix </h2></3;i++){></pre></2;i++){></pre></arr.length;></pre></3;i++){></pre></=arr.length;i++){></pre></arr.length;i++)></pre></arr.length;i++)> Návrat pole z metody
Můžeme také vrátit pole z metody v Javě.
//Java Program to return an array from the method class TestReturnArray{ //creating method which returns an array static int[] get(){ return new int[]{10,30,50,90,60}; } public static void main(String args[]){ //calling method which returns an array int arr[]=get(); //printing the values of an array for(int i=0;i <arr.length;i++) system.out.println(arr[i]); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 10 30 50 90 60 </pre> <h2>ArrayIndexOutOfBoundsException</h2> <p>The Java Virtual Machine (JVM) throws an ArrayIndexOutOfBoundsException if length of the array in negative, equal to the array size or greater than the array size while traversing the array.</p> <pre> //Java Program to demonstrate the case of //ArrayIndexOutOfBoundsException in a Java Array. public class TestArrayException{ public static void main(String args[]){ int arr[]={50,60,70,80}; for(int i=0;i<=arr.length;i++){ system.out.println(arr[i]); } }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> Exception in thread 'main' java.lang.ArrayIndexOutOfBoundsException: 4 at TestArrayException.main(TestArrayException.java:5) 50 60 70 80 </pre> <hr> <h2>Multidimensional Array in Java</h2> <p>In such case, data is stored in row and column based index (also known as matrix form).</p> <p> <strong>Syntax to Declare Multidimensional Array in Java</strong> </p> <pre> dataType[][] arrayRefVar; (or) dataType [][]arrayRefVar; (or) dataType arrayRefVar[][]; (or) dataType []arrayRefVar[]; </pre> <p> <strong>Example to instantiate Multidimensional Array in Java</strong> </p> <pre> int[][] arr=new int[3][3];//3 row and 3 column </pre> <p> <strong>Example to initialize Multidimensional Array in Java</strong> </p> <pre> arr[0][0]=1; arr[0][1]=2; arr[0][2]=3; arr[1][0]=4; arr[1][1]=5; arr[1][2]=6; arr[2][0]=7; arr[2][1]=8; arr[2][2]=9; </pre> <h3>Example of Multidimensional Java Array</h3> <p>Let's see the simple example to declare, instantiate, initialize and print the 2Dimensional array.</p> <pre> //Java Program to illustrate the use of multidimensional array class Testarray3{ public static void main(String args[]){ //declaring and initializing 2D array int arr[][]={{1,2,3},{2,4,5},{4,4,5}}; //printing 2D array for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" system.out.print(arr[i][j]+\' \'); } system.out.println(); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 1 2 3 2 4 5 4 4 5 </pre> <h2>Jagged Array in Java</h2> <p>If we are creating odd number of columns in a 2D array, it is known as a jagged array. In other words, it is an array of arrays with different number of columns.</p> <pre> //Java Program to illustrate the jagged array class TestJaggedArray{ public static void main(String[] args){ //declaring a 2D array with odd columns int arr[][] = new int[3][]; arr[0] = new int[3]; arr[1] = new int[4]; arr[2] = new int[2]; //initializing a jagged array int count = 0; for (int i=0; i <arr.length; i++) for(int j="0;" <arr[i].length; j++) arr[i][j]="count++;" printing the data of a jagged array for (int i="0;" <arr.length; i++){ j++){ system.out.print(arr[i][j]+\' \'); } system.out.println(); new line < pre> <span> Test it Now </span> <p>Output:</p> <pre> 0 1 2 3 4 5 6 7 8 </pre> <hr> <h2>What is the class name of Java array?</h2> <p>In Java, an array is an object. For array object, a proxy class is created whose name can be obtained by getClass().getName() method on the object.</p> <pre> //Java Program to get the class name of array in Java class Testarray4{ public static void main(String args[]){ //declaration and initialization of array int arr[]={4,4,5}; //getting the class name of Java array Class c=arr.getClass(); String name=c.getName(); //printing the class name of Java array System.out.println(name); }} </pre> <span> Test it Now </span> <p>Output:</p> <pre> I </pre> <hr> <h2>Copying a Java Array</h2> <p>We can copy an array to another by the arraycopy() method of System class.</p> <p> <strong>Syntax of arraycopy method</strong> </p> <pre> public static void arraycopy( Object src, int srcPos,Object dest, int destPos, int length ) </pre> <h3>Example of Copying an Array in Java</h3> <pre> //Java Program to copy a source array into a destination array in Java class TestArrayCopyDemo { public static void main(String[] args) { //declaring a source array char[] copyFrom = { 'd', 'e', 'c', 'a', 'f', 'f', 'e', 'i', 'n', 'a', 't', 'e', 'd' }; //declaring a destination array char[] copyTo = new char[7]; //copying array using System.arraycopy() method System.arraycopy(copyFrom, 2, copyTo, 0, 7); //printing the destination array System.out.println(String.valueOf(copyTo)); } } </pre> <span> Test it Now </span> <p>Output:</p> <pre> caffein </pre> <hr> <h2>Cloning an Array in Java</h2> <p>Since, Java array implements the Cloneable interface, we can create the clone of the Java array. If we create the clone of a single-dimensional array, it creates the deep copy of the Java array. It means, it will copy the actual value. But, if we create the clone of a multidimensional array, it creates the shallow copy of the Java array which means it copies the references.</p> <pre> //Java Program to clone the array class Testarray1{ public static void main(String args[]){ int arr[]={33,3,4,5}; System.out.println('Printing original array:'); for(int i:arr) System.out.println(i); System.out.println('Printing clone of the array:'); int carr[]=arr.clone(); for(int i:carr) System.out.println(i); System.out.println('Are both equal?'); System.out.println(arr==carr); }} </pre> <p>Output:</p> <pre> Printing original array: 33 3 4 5 Printing clone of the array: 33 3 4 5 Are both equal? false </pre> <h2>Addition of 2 Matrices in Java</h2> <p>Let's see a simple example that adds two matrices.</p> <pre> //Java Program to demonstrate the addition of two matrices in Java class Testarray5{ public static void main(String args[]){ //creating two matrices int a[][]={{1,3,4},{3,4,5}}; int b[][]={{1,3,4},{3,4,5}}; //creating another matrix to store the sum of two matrices int c[][]=new int[2][3]; //adding and printing addition of 2 matrices for(int i=0;i<2;i++){ for(int j="0;j<3;j++){" c[i][j]="a[i][j]+b[i][j];" system.out.print(c[i][j]+\' \'); } system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 2 6 8 6 8 10 </pre> <h2>Multiplication of 2 Matrices in Java</h2> <p>In the case of matrix multiplication, a one-row element of the first matrix is multiplied by all the columns of the second matrix which can be understood by the image given below.</p> <img src="//techcodeview.com/img/java-object-class/39/java-arrays.webp" alt="Matrix Multiplication in Java"> <p>Let's see a simple example to multiply two matrices of 3 rows and 3 columns.</p> <pre> //Java Program to multiply two matrices public class MatrixMultiplicationExample{ public static void main(String args[]){ //creating two matrices int a[][]={{1,1,1},{2,2,2},{3,3,3}}; int b[][]={{1,1,1},{2,2,2},{3,3,3}}; //creating another matrix to store the multiplication of two matrices int c[][]=new int[3][3]; //3 rows and 3 columns //multiplying and printing multiplication of 2 matrices for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" c[i][j]="0;" k="0;k<3;k++)" { c[i][j]+="a[i][k]*b[k][j];" } end of loop system.out.print(c[i][j]+\' \'); printing matrix element system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 6 6 6 12 12 12 18 18 18 </pre> <h3>Related Topics</h3> <h2> 1) Java Program to copy all elements of one array into another array </h2> <h2> 2) Java Program to find the frequency of each element in the array </h2> <h2> 3) Java Program to left rotate the elements of an array </h2> <h2> 4) Java Program to print the duplicate elements of an array </h2> <h2> 5) Java Program to print the elements of an array </h2> <h2> 6) Java Program to print the elements of an array in reverse order </h2> <h2> 7) Java Program to print the elements of an array present on even position </h2> <h2> 8) Java Program to print the elements of an array present on odd position </h2> <h2> 9) Java Program to print the largest element in an array </h2> <h2> 10) Java Program to print the smallest element in an array </h2> <h2> 11) Java Program to print the number of elements present in an array </h2> <h2> 12) Java Program to print the sum of all the items of the array </h2> <h2> 13) Java Program to right rotate the elements of an array </h2> <h2> 14) Java Program to sort the elements of an array in ascending order </h2> <h2> 15) Java Program to sort the elements of an array in descending order </h2> <h2>16) Find 3rd Largest Number in an Array </h2> <h2>17) Find 2nd Largest Number in an Array </h2> <h2>18) Find Largest Number in an Array </h2> <h2>19) Find 2nd Smallest Number in an Array </h2> <h2>20) Find Smallest Number in an Array </h2> <h2>21) Remove Duplicate Element in an Array </h2> <h2>22) Add Two Matrices </h2> <h2>23) <a href="/java-program-multiply-two-matrices">Multiply Two Matrices</a> </h2> <h2>24) Print Odd and Even Number from an Array </h2> <h2>25) Transpose matrix </h2> <h2> 26) Java Program to subtract the two matrices </h2> <h2> 27) Java Program to determine whether a given matrix is an identity matrix </h2> <h2> 28) Java Program to determine whether a given matrix is a sparse matrix </h2> <h2> 29) Java Program to determine whether two matrices are equal </h2> <h2> 30) Java Program to display the lower triangular matrix </h2> <h2> 31) Java Program to display the upper triangular matrix </h2> <h2> 32) Java Program to find the frequency of odd & even numbers in the given matrix </h2> <h2> 33) Java Program to find the product of two matrices </h2> <h2> 34) Java Program to find the sum of each row and each column of a matrix </h2> <h2> 35) Java Program to find the transpose of a given matrix </h2></3;i++){></pre></2;i++){></pre></arr.length;></pre></3;i++){></pre></=arr.length;i++){></pre></arr.length;i++)> Výjimka ArrayIndexOutOfBounds
Java Virtual Machine (JVM) vyvolá výjimku ArrayIndexOutOfBoundsException, pokud je délka pole záporná, rovná se velikosti pole nebo je větší než velikost pole při procházení pole.
//Java Program to demonstrate the case of //ArrayIndexOutOfBoundsException in a Java Array. public class TestArrayException{ public static void main(String args[]){ int arr[]={50,60,70,80}; for(int i=0;i<=arr.length;i++){ system.out.println(arr[i]); } }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> Exception in thread 'main' java.lang.ArrayIndexOutOfBoundsException: 4 at TestArrayException.main(TestArrayException.java:5) 50 60 70 80 </pre> <hr> <h2>Multidimensional Array in Java</h2> <p>In such case, data is stored in row and column based index (also known as matrix form).</p> <p> <strong>Syntax to Declare Multidimensional Array in Java</strong> </p> <pre> dataType[][] arrayRefVar; (or) dataType [][]arrayRefVar; (or) dataType arrayRefVar[][]; (or) dataType []arrayRefVar[]; </pre> <p> <strong>Example to instantiate Multidimensional Array in Java</strong> </p> <pre> int[][] arr=new int[3][3];//3 row and 3 column </pre> <p> <strong>Example to initialize Multidimensional Array in Java</strong> </p> <pre> arr[0][0]=1; arr[0][1]=2; arr[0][2]=3; arr[1][0]=4; arr[1][1]=5; arr[1][2]=6; arr[2][0]=7; arr[2][1]=8; arr[2][2]=9; </pre> <h3>Example of Multidimensional Java Array</h3> <p>Let's see the simple example to declare, instantiate, initialize and print the 2Dimensional array.</p> <pre> //Java Program to illustrate the use of multidimensional array class Testarray3{ public static void main(String args[]){ //declaring and initializing 2D array int arr[][]={{1,2,3},{2,4,5},{4,4,5}}; //printing 2D array for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" system.out.print(arr[i][j]+\' \'); } system.out.println(); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 1 2 3 2 4 5 4 4 5 </pre> <h2>Jagged Array in Java</h2> <p>If we are creating odd number of columns in a 2D array, it is known as a jagged array. In other words, it is an array of arrays with different number of columns.</p> <pre> //Java Program to illustrate the jagged array class TestJaggedArray{ public static void main(String[] args){ //declaring a 2D array with odd columns int arr[][] = new int[3][]; arr[0] = new int[3]; arr[1] = new int[4]; arr[2] = new int[2]; //initializing a jagged array int count = 0; for (int i=0; i <arr.length; i++) for(int j="0;" <arr[i].length; j++) arr[i][j]="count++;" printing the data of a jagged array for (int i="0;" <arr.length; i++){ j++){ system.out.print(arr[i][j]+\' \'); } system.out.println(); new line < pre> <span> Test it Now </span> <p>Output:</p> <pre> 0 1 2 3 4 5 6 7 8 </pre> <hr> <h2>What is the class name of Java array?</h2> <p>In Java, an array is an object. For array object, a proxy class is created whose name can be obtained by getClass().getName() method on the object.</p> <pre> //Java Program to get the class name of array in Java class Testarray4{ public static void main(String args[]){ //declaration and initialization of array int arr[]={4,4,5}; //getting the class name of Java array Class c=arr.getClass(); String name=c.getName(); //printing the class name of Java array System.out.println(name); }} </pre> <span> Test it Now </span> <p>Output:</p> <pre> I </pre> <hr> <h2>Copying a Java Array</h2> <p>We can copy an array to another by the arraycopy() method of System class.</p> <p> <strong>Syntax of arraycopy method</strong> </p> <pre> public static void arraycopy( Object src, int srcPos,Object dest, int destPos, int length ) </pre> <h3>Example of Copying an Array in Java</h3> <pre> //Java Program to copy a source array into a destination array in Java class TestArrayCopyDemo { public static void main(String[] args) { //declaring a source array char[] copyFrom = { 'd', 'e', 'c', 'a', 'f', 'f', 'e', 'i', 'n', 'a', 't', 'e', 'd' }; //declaring a destination array char[] copyTo = new char[7]; //copying array using System.arraycopy() method System.arraycopy(copyFrom, 2, copyTo, 0, 7); //printing the destination array System.out.println(String.valueOf(copyTo)); } } </pre> <span> Test it Now </span> <p>Output:</p> <pre> caffein </pre> <hr> <h2>Cloning an Array in Java</h2> <p>Since, Java array implements the Cloneable interface, we can create the clone of the Java array. If we create the clone of a single-dimensional array, it creates the deep copy of the Java array. It means, it will copy the actual value. But, if we create the clone of a multidimensional array, it creates the shallow copy of the Java array which means it copies the references.</p> <pre> //Java Program to clone the array class Testarray1{ public static void main(String args[]){ int arr[]={33,3,4,5}; System.out.println('Printing original array:'); for(int i:arr) System.out.println(i); System.out.println('Printing clone of the array:'); int carr[]=arr.clone(); for(int i:carr) System.out.println(i); System.out.println('Are both equal?'); System.out.println(arr==carr); }} </pre> <p>Output:</p> <pre> Printing original array: 33 3 4 5 Printing clone of the array: 33 3 4 5 Are both equal? false </pre> <h2>Addition of 2 Matrices in Java</h2> <p>Let's see a simple example that adds two matrices.</p> <pre> //Java Program to demonstrate the addition of two matrices in Java class Testarray5{ public static void main(String args[]){ //creating two matrices int a[][]={{1,3,4},{3,4,5}}; int b[][]={{1,3,4},{3,4,5}}; //creating another matrix to store the sum of two matrices int c[][]=new int[2][3]; //adding and printing addition of 2 matrices for(int i=0;i<2;i++){ for(int j="0;j<3;j++){" c[i][j]="a[i][j]+b[i][j];" system.out.print(c[i][j]+\' \'); } system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 2 6 8 6 8 10 </pre> <h2>Multiplication of 2 Matrices in Java</h2> <p>In the case of matrix multiplication, a one-row element of the first matrix is multiplied by all the columns of the second matrix which can be understood by the image given below.</p> <img src="//techcodeview.com/img/java-object-class/39/java-arrays.webp" alt="Matrix Multiplication in Java"> <p>Let's see a simple example to multiply two matrices of 3 rows and 3 columns.</p> <pre> //Java Program to multiply two matrices public class MatrixMultiplicationExample{ public static void main(String args[]){ //creating two matrices int a[][]={{1,1,1},{2,2,2},{3,3,3}}; int b[][]={{1,1,1},{2,2,2},{3,3,3}}; //creating another matrix to store the multiplication of two matrices int c[][]=new int[3][3]; //3 rows and 3 columns //multiplying and printing multiplication of 2 matrices for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" c[i][j]="0;" k="0;k<3;k++)" { c[i][j]+="a[i][k]*b[k][j];" } end of loop system.out.print(c[i][j]+\' \'); printing matrix element system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 6 6 6 12 12 12 18 18 18 </pre> <h3>Related Topics</h3> <h2> 1) Java Program to copy all elements of one array into another array </h2> <h2> 2) Java Program to find the frequency of each element in the array </h2> <h2> 3) Java Program to left rotate the elements of an array </h2> <h2> 4) Java Program to print the duplicate elements of an array </h2> <h2> 5) Java Program to print the elements of an array </h2> <h2> 6) Java Program to print the elements of an array in reverse order </h2> <h2> 7) Java Program to print the elements of an array present on even position </h2> <h2> 8) Java Program to print the elements of an array present on odd position </h2> <h2> 9) Java Program to print the largest element in an array </h2> <h2> 10) Java Program to print the smallest element in an array </h2> <h2> 11) Java Program to print the number of elements present in an array </h2> <h2> 12) Java Program to print the sum of all the items of the array </h2> <h2> 13) Java Program to right rotate the elements of an array </h2> <h2> 14) Java Program to sort the elements of an array in ascending order </h2> <h2> 15) Java Program to sort the elements of an array in descending order </h2> <h2>16) Find 3rd Largest Number in an Array </h2> <h2>17) Find 2nd Largest Number in an Array </h2> <h2>18) Find Largest Number in an Array </h2> <h2>19) Find 2nd Smallest Number in an Array </h2> <h2>20) Find Smallest Number in an Array </h2> <h2>21) Remove Duplicate Element in an Array </h2> <h2>22) Add Two Matrices </h2> <h2>23) <a href="/java-program-multiply-two-matrices">Multiply Two Matrices</a> </h2> <h2>24) Print Odd and Even Number from an Array </h2> <h2>25) Transpose matrix </h2> <h2> 26) Java Program to subtract the two matrices </h2> <h2> 27) Java Program to determine whether a given matrix is an identity matrix </h2> <h2> 28) Java Program to determine whether a given matrix is a sparse matrix </h2> <h2> 29) Java Program to determine whether two matrices are equal </h2> <h2> 30) Java Program to display the lower triangular matrix </h2> <h2> 31) Java Program to display the upper triangular matrix </h2> <h2> 32) Java Program to find the frequency of odd & even numbers in the given matrix </h2> <h2> 33) Java Program to find the product of two matrices </h2> <h2> 34) Java Program to find the sum of each row and each column of a matrix </h2> <h2> 35) Java Program to find the transpose of a given matrix </h2></3;i++){></pre></2;i++){></pre></arr.length;></pre></3;i++){></pre></=arr.length;i++){> Multidimenzionální pole v Javě
V takovém případě jsou data uložena v řádkovém a sloupcovém indexu (také známém jako maticová forma).
Syntaxe pro deklaraci vícerozměrného pole v Javě
dataType[][] arrayRefVar; (or) dataType [][]arrayRefVar; (or) dataType arrayRefVar[][]; (or) dataType []arrayRefVar[];
Příklad pro vytvoření instance Multidimenzionálního pole v Javě
int[][] arr=new int[3][3];//3 row and 3 column
Příklad inicializace vícerozměrného pole v Javě
arr[0][0]=1; arr[0][1]=2; arr[0][2]=3; arr[1][0]=4; arr[1][1]=5; arr[1][2]=6; arr[2][0]=7; arr[2][1]=8; arr[2][2]=9;
Příklad multidimenzionálního pole Java
Podívejme se na jednoduchý příklad pro deklaraci, instanci, inicializaci a tisk 2Dimensional pole.
java mapy
//Java Program to illustrate the use of multidimensional array class Testarray3{ public static void main(String args[]){ //declaring and initializing 2D array int arr[][]={{1,2,3},{2,4,5},{4,4,5}}; //printing 2D array for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" system.out.print(arr[i][j]+\\' \\'); } system.out.println(); }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 1 2 3 2 4 5 4 4 5 </pre> <h2>Jagged Array in Java</h2> <p>If we are creating odd number of columns in a 2D array, it is known as a jagged array. In other words, it is an array of arrays with different number of columns.</p> <pre> //Java Program to illustrate the jagged array class TestJaggedArray{ public static void main(String[] args){ //declaring a 2D array with odd columns int arr[][] = new int[3][]; arr[0] = new int[3]; arr[1] = new int[4]; arr[2] = new int[2]; //initializing a jagged array int count = 0; for (int i=0; i <arr.length; i++) for(int j="0;" <arr[i].length; j++) arr[i][j]="count++;" printing the data of a jagged array for (int i="0;" <arr.length; i++){ j++){ system.out.print(arr[i][j]+\\' \\'); } system.out.println(); new line < pre> <span> Test it Now </span> <p>Output:</p> <pre> 0 1 2 3 4 5 6 7 8 </pre> <hr> <h2>What is the class name of Java array?</h2> <p>In Java, an array is an object. For array object, a proxy class is created whose name can be obtained by getClass().getName() method on the object.</p> <pre> //Java Program to get the class name of array in Java class Testarray4{ public static void main(String args[]){ //declaration and initialization of array int arr[]={4,4,5}; //getting the class name of Java array Class c=arr.getClass(); String name=c.getName(); //printing the class name of Java array System.out.println(name); }} </pre> <span> Test it Now </span> <p>Output:</p> <pre> I </pre> <hr> <h2>Copying a Java Array</h2> <p>We can copy an array to another by the arraycopy() method of System class.</p> <p> <strong>Syntax of arraycopy method</strong> </p> <pre> public static void arraycopy( Object src, int srcPos,Object dest, int destPos, int length ) </pre> <h3>Example of Copying an Array in Java</h3> <pre> //Java Program to copy a source array into a destination array in Java class TestArrayCopyDemo { public static void main(String[] args) { //declaring a source array char[] copyFrom = { 'd', 'e', 'c', 'a', 'f', 'f', 'e', 'i', 'n', 'a', 't', 'e', 'd' }; //declaring a destination array char[] copyTo = new char[7]; //copying array using System.arraycopy() method System.arraycopy(copyFrom, 2, copyTo, 0, 7); //printing the destination array System.out.println(String.valueOf(copyTo)); } } </pre> <span> Test it Now </span> <p>Output:</p> <pre> caffein </pre> <hr> <h2>Cloning an Array in Java</h2> <p>Since, Java array implements the Cloneable interface, we can create the clone of the Java array. If we create the clone of a single-dimensional array, it creates the deep copy of the Java array. It means, it will copy the actual value. But, if we create the clone of a multidimensional array, it creates the shallow copy of the Java array which means it copies the references.</p> <pre> //Java Program to clone the array class Testarray1{ public static void main(String args[]){ int arr[]={33,3,4,5}; System.out.println('Printing original array:'); for(int i:arr) System.out.println(i); System.out.println('Printing clone of the array:'); int carr[]=arr.clone(); for(int i:carr) System.out.println(i); System.out.println('Are both equal?'); System.out.println(arr==carr); }} </pre> <p>Output:</p> <pre> Printing original array: 33 3 4 5 Printing clone of the array: 33 3 4 5 Are both equal? false </pre> <h2>Addition of 2 Matrices in Java</h2> <p>Let's see a simple example that adds two matrices.</p> <pre> //Java Program to demonstrate the addition of two matrices in Java class Testarray5{ public static void main(String args[]){ //creating two matrices int a[][]={{1,3,4},{3,4,5}}; int b[][]={{1,3,4},{3,4,5}}; //creating another matrix to store the sum of two matrices int c[][]=new int[2][3]; //adding and printing addition of 2 matrices for(int i=0;i<2;i++){ for(int j="0;j<3;j++){" c[i][j]="a[i][j]+b[i][j];" system.out.print(c[i][j]+\\' \\'); } system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 2 6 8 6 8 10 </pre> <h2>Multiplication of 2 Matrices in Java</h2> <p>In the case of matrix multiplication, a one-row element of the first matrix is multiplied by all the columns of the second matrix which can be understood by the image given below.</p> <img src="//techcodeview.com/img/java-object-class/39/java-arrays.webp" alt="Matrix Multiplication in Java"> <p>Let's see a simple example to multiply two matrices of 3 rows and 3 columns.</p> <pre> //Java Program to multiply two matrices public class MatrixMultiplicationExample{ public static void main(String args[]){ //creating two matrices int a[][]={{1,1,1},{2,2,2},{3,3,3}}; int b[][]={{1,1,1},{2,2,2},{3,3,3}}; //creating another matrix to store the multiplication of two matrices int c[][]=new int[3][3]; //3 rows and 3 columns //multiplying and printing multiplication of 2 matrices for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" c[i][j]="0;" k="0;k<3;k++)" { c[i][j]+="a[i][k]*b[k][j];" } end of loop system.out.print(c[i][j]+\\' \\'); printing matrix element system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 6 6 6 12 12 12 18 18 18 </pre> <h3>Related Topics</h3> <h2> 1) Java Program to copy all elements of one array into another array </h2> <h2> 2) Java Program to find the frequency of each element in the array </h2> <h2> 3) Java Program to left rotate the elements of an array </h2> <h2> 4) Java Program to print the duplicate elements of an array </h2> <h2> 5) Java Program to print the elements of an array </h2> <h2> 6) Java Program to print the elements of an array in reverse order </h2> <h2> 7) Java Program to print the elements of an array present on even position </h2> <h2> 8) Java Program to print the elements of an array present on odd position </h2> <h2> 9) Java Program to print the largest element in an array </h2> <h2> 10) Java Program to print the smallest element in an array </h2> <h2> 11) Java Program to print the number of elements present in an array </h2> <h2> 12) Java Program to print the sum of all the items of the array </h2> <h2> 13) Java Program to right rotate the elements of an array </h2> <h2> 14) Java Program to sort the elements of an array in ascending order </h2> <h2> 15) Java Program to sort the elements of an array in descending order </h2> <h2>16) Find 3rd Largest Number in an Array </h2> <h2>17) Find 2nd Largest Number in an Array </h2> <h2>18) Find Largest Number in an Array </h2> <h2>19) Find 2nd Smallest Number in an Array </h2> <h2>20) Find Smallest Number in an Array </h2> <h2>21) Remove Duplicate Element in an Array </h2> <h2>22) Add Two Matrices </h2> <h2>23) <a href="/java-program-multiply-two-matrices">Multiply Two Matrices</a> </h2> <h2>24) Print Odd and Even Number from an Array </h2> <h2>25) Transpose matrix </h2> <h2> 26) Java Program to subtract the two matrices </h2> <h2> 27) Java Program to determine whether a given matrix is an identity matrix </h2> <h2> 28) Java Program to determine whether a given matrix is a sparse matrix </h2> <h2> 29) Java Program to determine whether two matrices are equal </h2> <h2> 30) Java Program to display the lower triangular matrix </h2> <h2> 31) Java Program to display the upper triangular matrix </h2> <h2> 32) Java Program to find the frequency of odd & even numbers in the given matrix </h2> <h2> 33) Java Program to find the product of two matrices </h2> <h2> 34) Java Program to find the sum of each row and each column of a matrix </h2> <h2> 35) Java Program to find the transpose of a given matrix </h2></3;i++){></pre></2;i++){></pre></arr.length;></pre></3;i++){> Jagged Array v Javě
Pokud vytváříme lichý počet sloupců ve 2D poli, nazýváme to zubaté pole. Jinými slovy, je to pole polí s různým počtem sloupců.
//Java Program to illustrate the jagged array class TestJaggedArray{ public static void main(String[] args){ //declaring a 2D array with odd columns int arr[][] = new int[3][]; arr[0] = new int[3]; arr[1] = new int[4]; arr[2] = new int[2]; //initializing a jagged array int count = 0; for (int i=0; i <arr.length; i++) for(int j="0;" <arr[i].length; j++) arr[i][j]="count++;" printing the data of a jagged array for (int i="0;" <arr.length; i++){ j++){ system.out.print(arr[i][j]+\\' \\'); } system.out.println(); new line < pre> <span> Test it Now </span> <p>Output:</p> <pre> 0 1 2 3 4 5 6 7 8 </pre> <hr> <h2>What is the class name of Java array?</h2> <p>In Java, an array is an object. For array object, a proxy class is created whose name can be obtained by getClass().getName() method on the object.</p> <pre> //Java Program to get the class name of array in Java class Testarray4{ public static void main(String args[]){ //declaration and initialization of array int arr[]={4,4,5}; //getting the class name of Java array Class c=arr.getClass(); String name=c.getName(); //printing the class name of Java array System.out.println(name); }} </pre> <span> Test it Now </span> <p>Output:</p> <pre> I </pre> <hr> <h2>Copying a Java Array</h2> <p>We can copy an array to another by the arraycopy() method of System class.</p> <p> <strong>Syntax of arraycopy method</strong> </p> <pre> public static void arraycopy( Object src, int srcPos,Object dest, int destPos, int length ) </pre> <h3>Example of Copying an Array in Java</h3> <pre> //Java Program to copy a source array into a destination array in Java class TestArrayCopyDemo { public static void main(String[] args) { //declaring a source array char[] copyFrom = { 'd', 'e', 'c', 'a', 'f', 'f', 'e', 'i', 'n', 'a', 't', 'e', 'd' }; //declaring a destination array char[] copyTo = new char[7]; //copying array using System.arraycopy() method System.arraycopy(copyFrom, 2, copyTo, 0, 7); //printing the destination array System.out.println(String.valueOf(copyTo)); } } </pre> <span> Test it Now </span> <p>Output:</p> <pre> caffein </pre> <hr> <h2>Cloning an Array in Java</h2> <p>Since, Java array implements the Cloneable interface, we can create the clone of the Java array. If we create the clone of a single-dimensional array, it creates the deep copy of the Java array. It means, it will copy the actual value. But, if we create the clone of a multidimensional array, it creates the shallow copy of the Java array which means it copies the references.</p> <pre> //Java Program to clone the array class Testarray1{ public static void main(String args[]){ int arr[]={33,3,4,5}; System.out.println('Printing original array:'); for(int i:arr) System.out.println(i); System.out.println('Printing clone of the array:'); int carr[]=arr.clone(); for(int i:carr) System.out.println(i); System.out.println('Are both equal?'); System.out.println(arr==carr); }} </pre> <p>Output:</p> <pre> Printing original array: 33 3 4 5 Printing clone of the array: 33 3 4 5 Are both equal? false </pre> <h2>Addition of 2 Matrices in Java</h2> <p>Let's see a simple example that adds two matrices.</p> <pre> //Java Program to demonstrate the addition of two matrices in Java class Testarray5{ public static void main(String args[]){ //creating two matrices int a[][]={{1,3,4},{3,4,5}}; int b[][]={{1,3,4},{3,4,5}}; //creating another matrix to store the sum of two matrices int c[][]=new int[2][3]; //adding and printing addition of 2 matrices for(int i=0;i<2;i++){ for(int j="0;j<3;j++){" c[i][j]="a[i][j]+b[i][j];" system.out.print(c[i][j]+\\' \\'); } system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 2 6 8 6 8 10 </pre> <h2>Multiplication of 2 Matrices in Java</h2> <p>In the case of matrix multiplication, a one-row element of the first matrix is multiplied by all the columns of the second matrix which can be understood by the image given below.</p> <img src="//techcodeview.com/img/java-object-class/39/java-arrays.webp" alt="Matrix Multiplication in Java"> <p>Let's see a simple example to multiply two matrices of 3 rows and 3 columns.</p> <pre> //Java Program to multiply two matrices public class MatrixMultiplicationExample{ public static void main(String args[]){ //creating two matrices int a[][]={{1,1,1},{2,2,2},{3,3,3}}; int b[][]={{1,1,1},{2,2,2},{3,3,3}}; //creating another matrix to store the multiplication of two matrices int c[][]=new int[3][3]; //3 rows and 3 columns //multiplying and printing multiplication of 2 matrices for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" c[i][j]="0;" k="0;k<3;k++)" { c[i][j]+="a[i][k]*b[k][j];" } end of loop system.out.print(c[i][j]+\\' \\'); printing matrix element system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 6 6 6 12 12 12 18 18 18 </pre> <h3>Related Topics</h3> <h2> 1) Java Program to copy all elements of one array into another array </h2> <h2> 2) Java Program to find the frequency of each element in the array </h2> <h2> 3) Java Program to left rotate the elements of an array </h2> <h2> 4) Java Program to print the duplicate elements of an array </h2> <h2> 5) Java Program to print the elements of an array </h2> <h2> 6) Java Program to print the elements of an array in reverse order </h2> <h2> 7) Java Program to print the elements of an array present on even position </h2> <h2> 8) Java Program to print the elements of an array present on odd position </h2> <h2> 9) Java Program to print the largest element in an array </h2> <h2> 10) Java Program to print the smallest element in an array </h2> <h2> 11) Java Program to print the number of elements present in an array </h2> <h2> 12) Java Program to print the sum of all the items of the array </h2> <h2> 13) Java Program to right rotate the elements of an array </h2> <h2> 14) Java Program to sort the elements of an array in ascending order </h2> <h2> 15) Java Program to sort the elements of an array in descending order </h2> <h2>16) Find 3rd Largest Number in an Array </h2> <h2>17) Find 2nd Largest Number in an Array </h2> <h2>18) Find Largest Number in an Array </h2> <h2>19) Find 2nd Smallest Number in an Array </h2> <h2>20) Find Smallest Number in an Array </h2> <h2>21) Remove Duplicate Element in an Array </h2> <h2>22) Add Two Matrices </h2> <h2>23) <a href="/java-program-multiply-two-matrices">Multiply Two Matrices</a> </h2> <h2>24) Print Odd and Even Number from an Array </h2> <h2>25) Transpose matrix </h2> <h2> 26) Java Program to subtract the two matrices </h2> <h2> 27) Java Program to determine whether a given matrix is an identity matrix </h2> <h2> 28) Java Program to determine whether a given matrix is a sparse matrix </h2> <h2> 29) Java Program to determine whether two matrices are equal </h2> <h2> 30) Java Program to display the lower triangular matrix </h2> <h2> 31) Java Program to display the upper triangular matrix </h2> <h2> 32) Java Program to find the frequency of odd & even numbers in the given matrix </h2> <h2> 33) Java Program to find the product of two matrices </h2> <h2> 34) Java Program to find the sum of each row and each column of a matrix </h2> <h2> 35) Java Program to find the transpose of a given matrix </h2></3;i++){></pre></2;i++){></pre></arr.length;> Jaký je název třídy pole Java?
V Javě je pole objekt. Pro objekt pole je vytvořena proxy třída, jejíž název lze získat metodou getClass().getName() na objektu.
//Java Program to get the class name of array in Java class Testarray4{ public static void main(String args[]){ //declaration and initialization of array int arr[]={4,4,5}; //getting the class name of Java array Class c=arr.getClass(); String name=c.getName(); //printing the class name of Java array System.out.println(name); }} Otestujte to hned Výstup:
I
Kopírování pole Java
Pole můžeme zkopírovat do jiného pomocí metody arraycopy() třídy System.
Syntaxe metody arraycopy
public static void arraycopy( Object src, int srcPos,Object dest, int destPos, int length )
Příklad kopírování pole v Javě
//Java Program to copy a source array into a destination array in Java class TestArrayCopyDemo { public static void main(String[] args) { //declaring a source array char[] copyFrom = { 'd', 'e', 'c', 'a', 'f', 'f', 'e', 'i', 'n', 'a', 't', 'e', 'd' }; //declaring a destination array char[] copyTo = new char[7]; //copying array using System.arraycopy() method System.arraycopy(copyFrom, 2, copyTo, 0, 7); //printing the destination array System.out.println(String.valueOf(copyTo)); } } Otestujte to hned Výstup:
caffein
Klonování pole v Javě
Protože pole Java implementuje rozhraní Cloneable, můžeme vytvořit klon pole Java. Pokud vytvoříme klon jednorozměrného pole, vytvoří hlubokou kopii pole Java. To znamená, že bude kopírovat skutečnou hodnotu. Pokud však vytvoříme klon vícerozměrného pole, vytvoří se mělká kopie pole Java, což znamená, že zkopíruje odkazy.
//Java Program to clone the array class Testarray1{ public static void main(String args[]){ int arr[]={33,3,4,5}; System.out.println('Printing original array:'); for(int i:arr) System.out.println(i); System.out.println('Printing clone of the array:'); int carr[]=arr.clone(); for(int i:carr) System.out.println(i); System.out.println('Are both equal?'); System.out.println(arr==carr); }} Výstup:
Printing original array: 33 3 4 5 Printing clone of the array: 33 3 4 5 Are both equal? false
Přidání 2 matic v Javě
Podívejme se na jednoduchý příklad, který sečte dvě matice.
//Java Program to demonstrate the addition of two matrices in Java class Testarray5{ public static void main(String args[]){ //creating two matrices int a[][]={{1,3,4},{3,4,5}}; int b[][]={{1,3,4},{3,4,5}}; //creating another matrix to store the sum of two matrices int c[][]=new int[2][3]; //adding and printing addition of 2 matrices for(int i=0;i<2;i++){ for(int j="0;j<3;j++){" c[i][j]="a[i][j]+b[i][j];" system.out.print(c[i][j]+\\' \\'); } system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 2 6 8 6 8 10 </pre> <h2>Multiplication of 2 Matrices in Java</h2> <p>In the case of matrix multiplication, a one-row element of the first matrix is multiplied by all the columns of the second matrix which can be understood by the image given below.</p> <img src="//techcodeview.com/img/java-object-class/39/java-arrays.webp" alt="Matrix Multiplication in Java"> <p>Let's see a simple example to multiply two matrices of 3 rows and 3 columns.</p> <pre> //Java Program to multiply two matrices public class MatrixMultiplicationExample{ public static void main(String args[]){ //creating two matrices int a[][]={{1,1,1},{2,2,2},{3,3,3}}; int b[][]={{1,1,1},{2,2,2},{3,3,3}}; //creating another matrix to store the multiplication of two matrices int c[][]=new int[3][3]; //3 rows and 3 columns //multiplying and printing multiplication of 2 matrices for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" c[i][j]="0;" k="0;k<3;k++)" { c[i][j]+="a[i][k]*b[k][j];" } end of loop system.out.print(c[i][j]+\\' \\'); printing matrix element system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 6 6 6 12 12 12 18 18 18 </pre> <h3>Related Topics</h3> <h2> 1) Java Program to copy all elements of one array into another array </h2> <h2> 2) Java Program to find the frequency of each element in the array </h2> <h2> 3) Java Program to left rotate the elements of an array </h2> <h2> 4) Java Program to print the duplicate elements of an array </h2> <h2> 5) Java Program to print the elements of an array </h2> <h2> 6) Java Program to print the elements of an array in reverse order </h2> <h2> 7) Java Program to print the elements of an array present on even position </h2> <h2> 8) Java Program to print the elements of an array present on odd position </h2> <h2> 9) Java Program to print the largest element in an array </h2> <h2> 10) Java Program to print the smallest element in an array </h2> <h2> 11) Java Program to print the number of elements present in an array </h2> <h2> 12) Java Program to print the sum of all the items of the array </h2> <h2> 13) Java Program to right rotate the elements of an array </h2> <h2> 14) Java Program to sort the elements of an array in ascending order </h2> <h2> 15) Java Program to sort the elements of an array in descending order </h2> <h2>16) Find 3rd Largest Number in an Array </h2> <h2>17) Find 2nd Largest Number in an Array </h2> <h2>18) Find Largest Number in an Array </h2> <h2>19) Find 2nd Smallest Number in an Array </h2> <h2>20) Find Smallest Number in an Array </h2> <h2>21) Remove Duplicate Element in an Array </h2> <h2>22) Add Two Matrices </h2> <h2>23) <a href="/java-program-multiply-two-matrices">Multiply Two Matrices</a> </h2> <h2>24) Print Odd and Even Number from an Array </h2> <h2>25) Transpose matrix </h2> <h2> 26) Java Program to subtract the two matrices </h2> <h2> 27) Java Program to determine whether a given matrix is an identity matrix </h2> <h2> 28) Java Program to determine whether a given matrix is a sparse matrix </h2> <h2> 29) Java Program to determine whether two matrices are equal </h2> <h2> 30) Java Program to display the lower triangular matrix </h2> <h2> 31) Java Program to display the upper triangular matrix </h2> <h2> 32) Java Program to find the frequency of odd & even numbers in the given matrix </h2> <h2> 33) Java Program to find the product of two matrices </h2> <h2> 34) Java Program to find the sum of each row and each column of a matrix </h2> <h2> 35) Java Program to find the transpose of a given matrix </h2></3;i++){></pre></2;i++){> Násobení 2 matic v Javě
V případě násobení matic je jednořádkový prvek první matice vynásoben všemi sloupci druhé matice, což lze pochopit z obrázku níže.
Podívejme se na jednoduchý příklad násobení dvou matic o 3 řádcích a 3 sloupcích.
//Java Program to multiply two matrices public class MatrixMultiplicationExample{ public static void main(String args[]){ //creating two matrices int a[][]={{1,1,1},{2,2,2},{3,3,3}}; int b[][]={{1,1,1},{2,2,2},{3,3,3}}; //creating another matrix to store the multiplication of two matrices int c[][]=new int[3][3]; //3 rows and 3 columns //multiplying and printing multiplication of 2 matrices for(int i=0;i<3;i++){ for(int j="0;j<3;j++){" c[i][j]="0;" k="0;k<3;k++)" { c[i][j]+="a[i][k]*b[k][j];" } end of loop system.out.print(c[i][j]+\\' \\'); printing matrix element system.out.println(); new line }} < pre> <span> Test it Now </span> <p>Output:</p> <pre> 6 6 6 12 12 12 18 18 18 </pre> <h3>Related Topics</h3> <h2> 1) Java Program to copy all elements of one array into another array </h2> <h2> 2) Java Program to find the frequency of each element in the array </h2> <h2> 3) Java Program to left rotate the elements of an array </h2> <h2> 4) Java Program to print the duplicate elements of an array </h2> <h2> 5) Java Program to print the elements of an array </h2> <h2> 6) Java Program to print the elements of an array in reverse order </h2> <h2> 7) Java Program to print the elements of an array present on even position </h2> <h2> 8) Java Program to print the elements of an array present on odd position </h2> <h2> 9) Java Program to print the largest element in an array </h2> <h2> 10) Java Program to print the smallest element in an array </h2> <h2> 11) Java Program to print the number of elements present in an array </h2> <h2> 12) Java Program to print the sum of all the items of the array </h2> <h2> 13) Java Program to right rotate the elements of an array </h2> <h2> 14) Java Program to sort the elements of an array in ascending order </h2> <h2> 15) Java Program to sort the elements of an array in descending order </h2> <h2>16) Find 3rd Largest Number in an Array </h2> <h2>17) Find 2nd Largest Number in an Array </h2> <h2>18) Find Largest Number in an Array </h2> <h2>19) Find 2nd Smallest Number in an Array </h2> <h2>20) Find Smallest Number in an Array </h2> <h2>21) Remove Duplicate Element in an Array </h2> <h2>22) Add Two Matrices </h2> <h2>23) <a href="/java-program-multiply-two-matrices">Multiply Two Matrices</a> </h2> <h2>24) Print Odd and Even Number from an Array </h2> <h2>25) Transpose matrix </h2> <h2> 26) Java Program to subtract the two matrices </h2> <h2> 27) Java Program to determine whether a given matrix is an identity matrix </h2> <h2> 28) Java Program to determine whether a given matrix is a sparse matrix </h2> <h2> 29) Java Program to determine whether two matrices are equal </h2> <h2> 30) Java Program to display the lower triangular matrix </h2> <h2> 31) Java Program to display the upper triangular matrix </h2> <h2> 32) Java Program to find the frequency of odd & even numbers in the given matrix </h2> <h2> 33) Java Program to find the product of two matrices </h2> <h2> 34) Java Program to find the sum of each row and each column of a matrix </h2> <h2> 35) Java Program to find the transpose of a given matrix </h2></3;i++){>