Define a String array in Java

Question

In java we can define main() method as both these ways.

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

.

public static void main(String... args) {          
    System.out.println("Hello World");
}

Both method takes array of String arguments. Now consider following scenario.

    String[] arr=new String[10]; // valid
    String... arr=new String[10];// invalid

Java never allows to create an array like this wayString... arr=new String[10];. But in above method implementation java allows to do so. My question is how java achieve this two different behavior for two scenarios?

I liked the question, hence upvoted it.

John Doe
– John Doe

2015-04-24 14:05:25 +00:00
Commented Apr 24, 2015 at 14:05 — John Doe
– John Doe, Commented Apr 24, 2015 at 14:05

Juned Ahsan · Accepted Answer · 2013-08-13 17:23:01Z

4

...

is a syntax for method arguments and not for variable definitions. The name of this notation is varargs, which is self explanatory i.e variable number of arguments.

edited Aug 13, 2013 at 17:23

answered Aug 13, 2013 at 16:59

Juned Ahsan

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Comments

Ankur Lathi · Accepted Answer · 2013-08-13 17:02:39Z

1

Variable argument or varargs(...) in Java used to write more flexible methods which can accept as many argument as you need not for initialization.

answered Aug 13, 2013 at 17:02

Ankur Lathi

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Comments

sanbhat · Accepted Answer · 2013-08-13 17:03:39Z

1

... refers to varargs and its main intention to make method more readable.

void method(String... args) {

}

can be called as

method("a"); OR method("a", "b"); OR method("a", "b", "c");

I see no point in using it in variable declaration, we can't do much with

String... a = {"a", "b"}

An array can anyways be declared with dynamic size

String[] arr = {"a"};

OR

String[] arr = {"a", "b"};

answered Aug 13, 2013 at 17:03

sanbhat

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Comments

fortran · Accepted Answer · 2013-08-13 17:03:03Z

0

You can use varargs in main because a method declared with varargs (...) is bytecode compatible with a declaration of a method with an array argument (for backwards compatibility). That does not mean that the same syntax is allowed for type declarations.

answered Aug 13, 2013 at 17:03

fortran

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