Found 9326 Articles for Object Oriented Programming

You should get a start time before making a call and end time after method execution. The difference is the time taken. ExampleLive Demoimport java.util.Calendar; public class Tester {    public static void main(String[] args) {       long startTime = Calendar.getInstance().getTimeInMillis();       longRunningMethod();       long endTime = Calendar.getInstance().getTimeInMillis();       System.out.println("Time taken: " + (endTime - startTime) + " ms");    }    public static void longRunningMethod() {       try {          Thread.sleep(1000);       } catch (InterruptedException e) {          e.printStackTrace();       }    } }OutputTime taken: 1012 ms

NullPointerException is a runtime exception and it is thrown when the application try to use an object reference which has a null value.For example, using a method on a null reference.Object ref = null; ref.toString(); // this will throw a NullPointerException

From Java 8 onwards, static methods are allowed in Java interfaces.An interface can also have static helper methods from Java 8 onwards. public interface vehicle {    default void print() {       System.out.println("I am a vehicle!");    }    static void blowHorn() {       System.out.println("Blowing horn!!!");    } }Default Method ExampleCreate the following Java program using any editor of your choice in, say, C:\> JAVA.Java8Tester.javaLive Demopublic class Java8Tester {    public static void main(String args[]) {       Vehicle vehicle = new Car(); vehicle.print();    } } interface Vehicle {    default void print() { ... Read More

Let us look at a simple code that will print the words Hello World.ExampleLive Demopublic class MyFirstJavaProgram {    /* This is my first java program. *    This will print 'Hello World' as the output */    public static void main(String []args) {       System.out.println("Hello World"); // prints Hello World    } }Let's look at how to save the file, compile, and run the program. Please follow the subsequent steps −Open notepad and add the code as above.Save the file as: MyFirstJavaProgram.java.Open a command prompt window and go to the directory where you saved the class. Assume ... Read More

Let us look at a simple code that will print the words Hello World.ExampleLive Demopublic class MyFirstJavaProgram {    /* This is my first java program.       * This will print 'Hello World' as the output    */    public static void main(String []args) {       System.out.println("Hello World");       // prints Hello World    } }Let's look at how to save the file, compile, and run the program. Please follow the subsequent steps −Open notepad and add the code as above.Save the file as: MyFirstJavaProgram.java.Open a command prompt window and go to the directory where ... Read More

Following example helps to determine the rows and columns of a two-dimensional array with the use of arrayname.length.ExampleFollowing example helps to determine the upper bound of a two dimensional array with the use of arrayname.length. public class Main {    public static void main(String args[]) {       String[][] data = new String[2][5];       System.out.println("Dimension 1: " + data.length);       System.out.println("Dimension 2: " + data[0].length);    } }OutputThe above code sample will produce the following result. Dimension 1: 2 Dimension 2: 5

Yes, use String.split() method to do it. See the example below −Examplepublic class Tester {    public static void main(String[] args) {       String text = "This,is,a,comma,seperated,string.";       String[] array = text.split(",");       for(String value:array) {          System.out.print(value + " ");       }    } }OutputThis is a comma seperated string.

You can simply iterate the byte array and print the byte using System.out.println() method.Examplepublic class Tester {    public static void main(String[] args) {       byte[] a = { 1,2,3};       for(int i=0; i< a.length ; i++) {          System.out.print(a[i] +" ");       }    } }Output1 2 3

Yes. Create a list to represent a 2D array and then use Collections.shuffle(list).Exampleimport java.util.ArrayList; import java.util.Collections; import java.util.List; public class Tester {    public static void main(String[] args) {       List rows = new ArrayList();       rows.add(new int[]{1,2,3});       rows.add(new int[]{4,5,6});       rows.add(new int[]{7,8,9});       System.out.println("Before Shuffle");       System.out.println("[0][0] : " + rows.get(0)[0]);       System.out.println("[1][1] : " + rows.get(1)[1]);       System.out.println("After Shuffle");       Collections.shuffle(rows);       System.out.println("[0][0] : " + rows.get(0)[0]);       System.out.println("[1][1] : " + rows.get(1)[1]);    } }OutputBefore Shuffle [0][0] : 1 [1][1] : 5 After Shuffle [0][0] : 7 [1][1] : 2

Following program shows how to initialize an array declared earlier.Examplepublic class Tester {    int a[];    public static void main(String[] args) {       Tester tester = new Tester();       tester.initialize();    }    private void initialize() {       a = new int[3];       a[0] = 0;       a[1] = 1;       a[2] = 2;       for(int i=0; i< a.length ; i++) {          System.out.print(a[i] +" ");       }    } }Output0 1 2