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Need Help

Madan Mohan
Ranch Hand

Joined: Dec 05, 2008
Posts: 30
Could someone please explain me how boxing and var - args work...
Kenneth Lomvey
Ranch Hand

Joined: Nov 08, 2008
Posts: 94
Hi Madan,

Welcome to JavaRanch. First of all, please use a Meaningful Subject Line when posting a question again.

Now read the topics below. You will get an answer for your question:

http://www.coderanch.com/t/417852/java-programmer-SCJP/certification/Var-Args

http://www.coderanch.com/t/269788/java-programmer-SCJP/certification/boxing-vs-var-args

http://www.coderanch.com/t/264482/java-programmer-SCJP/certification/var-arg-Boxing-Widening-ambiguous
Rajshekhar Paul
Ranch Hand

Joined: Oct 17, 2006
Posts: 140
Just to give an idea -

1. through var-args you can send zero as well as more than zero argument of same type to a method which has only one parameter(), i.e. var-arg parameter. a method can have only one var-arg parameter and it should be the last parameter if there are more than one parameter for that method.

2. boxing is used to have the primitive specific behavior in a wrapper class object.


When it's obvious that you have to do it, just do it without shattering your thoughts over different directions.
Madan Mohan
Ranch Hand

Joined: Dec 05, 2008
Posts: 30
Hi Raj,

Could you please explain me this paragraph with some example..I am not able to get it

"through var-args you can send zero as well as more than zero argument of same type to a method which has only one parameter(), i.e. var-arg parameter. a method can have only one var-arg parameter and it should be the last parameter if there are more than one parameter for that method."
Rajshekhar Paul
Ranch Hand

Joined: Oct 17, 2006
Posts: 140
Sure.



Hope, it helps you.
Ankit Garg
Sheriff

Joined: Aug 03, 2008
Posts: 9291
    
  17

Let me also try to explain you what raj meant

void method(String... args, int... i) //not allowed, cannot have more than one var-args in a method

-------------------------------------------------------------------------

void method(String... args, int i) //not allowed, var-arg must be the last parameter so the correct code would be

void method(int i, String... args)

-------------------------------------------------------------------------
void method(String... args)

now you can call this method as

method(); //no arguments
method("a"); //1 argument
method("a", "b"); //2 argument

and so on. i.e. you can pass any number of arguments to this method...

[Edit: Oops! I was not quick enough]
[ December 05, 2008: Message edited by: Ankit Garg ]

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subject: Need Help