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Thread: Please describe the output of the following program!

  1. #1
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    Post Please describe the output of the following program!

    I have seen this interview question on a site and executed it

    code:
    public class Main
    {
    public static void main(String l[])
    {
    String a,b;
    a="First";
    b="Second";
    swap(a,b);
    System.out.println(a);
    System.out.println(b);
    }
    private static void swap(String a, String b)
    {
    String temp=a;
    a=b;
    b=temp;
    }
    }
    The output is:
    First
    Second

    but i was expecting
    Second
    First

    can any one explain how??


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Please describe the output of the following program!

    Java passes args by value not reference. The swap method changed the values of the args it received, not the values of the variables whose values were passed to it.
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
    Member Ganeprog's Avatar
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    Default Re: Please describe the output of the following program!

    Hi,

    As norm said you changed only args values. So better you do one thing put print statement with in swap method.

    private static void swap(String a, String b)
    {
    String temp=a;
    a=b;
    b=temp;
    System.out.println(a);
    System.out.println(b);
    }
    }

    Thanks,

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