Java - pass by value and pass by reference

[marlajee Borstone]

Hi friends, I find this site as great site to increase knowledge. Thanks to JavaRanch !!

As I am stuck today as I could read somewhere Java supports only Pass-by-value and not pass-by-reference.

Can someone prove it that Java does not support Pass-by-Reference. I want to see some java beginner level code example for proof.

regards,
Dhaansumall

[Mark Vedder]

public class ExamplePassByValue
{
 
    public static void main(String[] args)
    {
        int x = 5;
        System.out.println("x is " + x + " before the method call");
        doSomething(x);
        System.out.println("After the method call, x is still " + x + " since it was passed in by value into the method.");
        System.out.println("Had it been passed by reference, its value would have changed.");
    }
 
    public static void doSomething (int y)
    {
        y = y + 5;
        System.out.println("In the method after adding 5 to it, y, which was passed in by value , is now " + y);
    }
}

This question gets asked a lot. Take a look at this and this recent threads on the subject. You can also search the beginner forum for pass by value and find a number of discussions on the subject.

[Mark Vedder]

You can also take a look at the Pass By Value campfire story (a fun name for a lesson) here at JavaRanch. It does a nice job of explaining the concept, and has some examples. Things get a little more confusing when dealing with objects and references to objects. The campfire story can help clear things up.
[ July 26, 2008: Message edited by: Mark Vedder ]