why I can't modify the reference of a class in that class

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public class A{
    void set(A k){
        k = null;
    }
}


        A a = new A();
        A b = new A();
        System.out.println(a);
        System.out.println(b);
        a.set(b);
        System.out.println(b);



The outputs:
business.CharacterCard$A@61de33
business.CharacterCard$A@14318bb
business.CharacterCard$A@14318bb

Posted 30-Sep-10 10:25am

jibeex

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Peter_in_2780 · Answer 1 · 2010-09-30T15:57:00

Java is a "pass by value" language, to quote David Flanagan's "Java in a Nutshell". So when you call a.set(b), the reference to b is copied into the local "k" of the method. That is then modified to null (as you can see if you use a debugger), but nothing has happened to the "b" in the caller.
Remember to vote for the answer, and mark it accepted if you like it. If you want to reply to this, make a comment, not another answer.