String array Vs String var args

[Krishan Chauhan]

Hi

Could anyone tell me the difference between these:

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

public static void main(String... args){}

Is it like that String array and String var args means the same thing?

Thanks
Krishan

[K Kiran Kumar]

In public static void main(String[] args), all the command line arguments were taken in args.
like: java somefile abc xyz
Here args[0]=abc
args[1]=xyz
But public static void main(String s1) is a normal static method. How come both will be the same....? I mean args[] is an array and args is a single String obj variable.
Did I answer your question??
[ May 09, 2008: Message edited by: K Kiran Kumar ]

[Wirianto Djunaidi]

Krishan,

When you see it from java application starting up as the point of entry then the public static void main() method, either String[] or String... is similar.

It make a different if you use it in regular method or call main from other method. With String[] signature when calling it you'll have this:

 XXX.main(new String[] { "one", "two", "three" });

when you have varargs you'll call it like this:

 XXX.main( "one", "two", "three" );

Does that help?
-DJ

[Krishan Chauhan]

Hi DJ

Thanks for your reply.

Do you mean to say that we can have something like this:
void callMe(int[] a){}

void callMe(int... b){}

Java treats both of them as duplicate method. Pls tell in what context they are different.



Thanks
Krishan

[Venkata Kumar]

Krishan,

Both the methods are identical for java compiler. The difference is that the way we can call these methods.

The method void callMe(int... b){} can be called as

callMe(new int[]{1,2,3});
callMe(1,2,3);

The method void callMe(int[] a){} can be called as

callMe(new int[]{1,2,3});    

-Sai

[Nitesh Kant]

This article will help you understand better.

This line from the article explains a lot:

It is still true that multiple arguments must be passed in an array, but the varargs feature automates and hides the process.

So, the compiler behind the scenes actually converts your var args method to a method with an array input.
This is the reason why you can have a var args method overloaded with an array as input because after compilation both of them will be identical.

[arulk pillai]

You can invoke with different number of arguments

  cnf.addNumbers(i1);
cnf.addNumbers(i1,i2);
cnf.addNumbers(i1,i2,5);
 

     public void addNumbers(Object ...args) {
//overrides baseclass methods
    }
   

[Krishan Chauhan]

Thanks All
It was really helpful.