There are many sites which are good resource for java interview questions-answers. Following is the list of most popular websites.Tutorialspoint www.tutorialspoint.comStackOverflow www.stackoverflow.comDZone www.dzone.comWikipedia www.wikipedia.orgIBM Developer Works www.ibm.com/developerworks/java/TechGig www.techgig.comGitHub www.github.comJava documentation docs.oracle.com/javase/Coursera www.coursera.org/JavaWorld www.javaworld.com/

There are many sites which are a good resource for java interview questions-answers. Following is the list of most popular websites.Tutorialspoint - www.tutorialspoint.comStackOverflow - www.stackoverflow.comDZone - www.dzone.comWikipedia - www.wikipedia.orgIBM Developer Works - www.ibm.com/developerworks/java/TechGig - www.techgig.comGitHub - www.github.comJava documentation - docs.oracle.com/javase/Coursera - www.coursera.org/JavaWorld - www.javaworld.com/

There are many sites which are a good resource for java interview questions-answers. Following is the list of most popular websites.Tutorialspoint  - www.tutorialspoint.comStackOverflow - www.stackoverflow.comDZone - www.dzone.comWikipedia - www.wikipedia.orgIBM Developer Works - www.ibm.com/developerworks/java/TechGig - www.techgig.comGitHub - www.github.comJava documentation - docs.oracle.com/javase/Coursera - www.coursera.org/JavaWorld - www.javaworld.com/

There are many sites which are a good resource for java interview questions-answers. Following is the list of most popular websites.Tutorialspoint - www.tutorialspoint.comStackOverflow - www.stackoverflow.comDZone - www.dzone.comWikipedia - www.wikipedia.orgIBM Developer Works - www.ibm.com/developerworks/java/TechGig - www.techgig.comGitHub - www.github.comJava documentation - docs.oracle.com/javase/Coursera - www.coursera.org/JavaWorld - www.javaworld.com/

From Java 8 onwards, the lambda expression is introduced which acts as function pointers.Lambda expressions are introduced in Java 8 and are touted to be the biggest feature of Java 8. Lambda expression facilitates functional programming and simplifies the development a lot.SyntaxA lambda expression is characterized by the following syntax.parameter -> expression bodyFollowing are the important characteristics of a lambda expression.Optional type declaration − No need to declare the type of a parameter. The compiler can inference the same from the value of the parameter.Optional parenthesis around parameter − No need to declare a single parameter in parenthesis. For multiple ... Read More

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