What are difference in different notations of String array in main method?

Question

I've used three types of notation while passing argument to main method in java.

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

Can anyone tell me the difference between above? Someone has used terms packed and non-packed data for explanation of first two, what are they, and is it related to these?

I think first two is somewhat related to coding convention. Am I right?

Answer 1

There is no actual difference, the variants are due to the different ways you can define an array in java syntax.

• The standard way to define and array

  String[] args

• C/C++ style exist from historical reasons

  String args[]

• Varargs style (When do you use varargs in Java?)

  String… args

All will compile to the same bytecode. I would stick with

public static void main(String[] args)

Answer 2

First two are same.

Infact all three are same at base. But the third kind is called as varargs and has a special purpose which is that it can be used as an optional parameter in methods. For example if you have a method that requires parameters int x, String... y then even you call the parameter without passing String... y as parameter argument, the code will compile. More information here: Methods, Optional Parameters and/or Accepting multiple Data Types

Also check this: Java varags method param list vs. array