Main method in java

public static void main(String arg[])

In Java we write public static void main (String args[]) instead of just main because:

public static void main(String arg[])   
      {  

      }  

public

The main method must be public because it is call from outside the class. It is called by jvm.

static

The main method must be static because without creating an instance jvm can call it.
If the main method is non static then it is must to create an instance of the class.

void

Main method doesn't return anything therefore it is void also.

Strings args[]

It is used for receiving any arbitrary number of arguments and save it in the array.