An Application

Example 3-1 is the source of an application that simply displays "Hello World" on stdout. The method accepts arguments in the invocation, but does nothing with them.

Example 3-1 A Java Application

//
// HelloWorld Application
//
class HelloWorldApp{
    public static void main (String args[]) {
        System.out.println ("Hello World");
    }
}

Note that, as in C, the method or function to be initially executed is identified as main. The keyword public lets the method be run by anyone; static makes main refer to the class HelloWorldApp and no other instance of the class; void says that main returns nothing; and args[] declares an array of type String

To compile the application, enter

$ javac HelloWorldApp.java

It is run by

$ java HelloWorldApp arg1 arg2 ...