Swap

[dchini]

I am puzzled with this code....

code:

class Funcs { public static void swap(Object a, Object b) {                 Object temp = a;                 a = b;                b = temp;         }     public static void main(String[] args) {                 String x= "hello";                 String y = "goodbye";                 System.out.println(x);                 System.out.println(y);                 swap(x,y);                 System.out.println(x);                 System.out.println(y);         }    }

It prints

hello
goodbye
hello
goodbye



I thought it should have printed

hello
goodbye
goodbye
hello

[OneOffDriveByPoster]

Java passes references by value. If you change what your function parameters refer to in a function, the change does not get reflected in the caller.

[A.J]

I think what u shud do is do the swapping in the main body instead of creating a separate function to do it for u.

[Saad]

A.J @ Sun Oct 26, 2008 10:03 pm wrote:

I think what u shud do is do the swapping in the main body instead of creating a separate function to do it for u.

But what happens in the case you want to swap a lot of things? Clearly you don't want to be copy/pasting the same code if you can make it a function.

[rdrake]

Aren't strings in Java immutable?

[OneOffDriveByPoster]

Saad @ Sun Oct 26, 2008 10:07 pm wrote:

A.J @ Sun Oct 26, 2008 10:03 pm wrote:

I think what u shud do is do the swapping in the main body instead of creating a separate function to do it for u.

But what happens in the case you want to swap a lot of things? Clearly you don't want to be copy/pasting the same code if you can make it a function.

For the sake of the OP:
If you are swapping a lot, you are more than likely to be swapping array elements or elements in a container. That is entirely possible to do in a helper function.
Hint: pass the array/container in with the indices/keys.