Java First Program - Tutorialsee

In this page, we will learn how to write the simple program of java. We can write a simple hello java program easily after installing the JDK. To create a simple java program, you need to create a class that contains main method. Let's understand the requirement first.

Hello java example


    class Simple{  
       public static void main(String args[]){
  	  System.out.println("Hello Java");  
     }  
  }

Output:Hello Java

Understanding first java program

★ Class :

keyword is used to declare a class in java.

★ public :

keyword 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. We will learn about the internal working of System.out.println statement later.

How many ways can we write a java program

★ Changing sequence of the modifiers, method prototype is not changed.


    static public void main(String args[])

★ Subscript notation in java array can be used after type, before variable or after variable.


    public static void main(String[] args)  
    public static void main(String []args)  
    public static void main(String args[])

★ You can provide var-args support to main method by passing 3 ellipses (dots)


    public static void main(String... args)

★ Having semicolon at the end of class in java is optional.


    class A{  
	static public void main(String... args){  
	System.out.println("hello java4");  
	}  
    };