Dinesh on Java: Hello World Example in Java

In this tutorial, we will discuss how to write the hello world java program. Creating hello world java example is too easy. Here, we have created a class named MyFirstJavaProgram that contains only main method and prints a message "hello world". It is the simple program of java.

Requirement for Hello World Java Example:

create the java program.
install the JDK if you don't have installed it, download the JDK and install it.
set path of the bin directory under jdk.
compile and execute the program.

Creating hello java example:
Let's create the hello world java program:

public 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
    }
}

Lets look at how to save the file, compile and run the program. Please follow the steps given below:

Open notepad and add the code as above.
Save the file as : MyFirstJavaProgram.java.
Open a command prompt window and go o the directory where you saved the class. Assume its F:\Javas.
Type ' javac MyFirstJavaProgram.java ' and press enter to compile your code. If there are no errors in your code the command
prompt will take you to the next line.( Assumption : The path variable is set).
Now type ' java MyFirstJavaProgram ' to run your program.
You will be able to see ' Hello World ' printed on the window.

output:
>
C : > javac MyFirstJavaProgram.java
C : > java MyFirstJavaProgram
Hello World

Understanding first java program:
Let's see what is the meaning of class, public, static, void, main, String[], System.out.println().

class is used to declare a class in java.
public is an access modifier which represents visibility, it means it is visible to all.
static is a keyword, if we declare any method as static, it is known as static method. The core advantage of static method is that there is no need to create object to invoke the static method. The main method is executed by the JVM, so it doesn't require to create object to invoke the main method. So it saves memory.
void is the return type of the method, it means it doesn't return any value.
main represents startup of the program.
String[] args is used for command line argument. We will learn it later.
System.out.println() is used print statement.

As displayed in the above diagram, write the MyFirstJavaProgram program of java in notepad and saved it as MyFirstJavaProgram.java. To compile and run this program, you need to open command prompt by Start -> All Programs -> Accessories -> command prompt.

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