Problem with code

[oregon]

I have this code:

Code:

 public class Test {
 public static void main (String[] args) {
 StringBuffer a = new StringBuffer("A");
 StringBuffer b = new StringBuffer("DD");
 chng(a,b);
 System.out.println(a+","+b);
 }

 static void chng(StringBuffer x, StringBuffer y) {
 y.append(x);
 System.out.println("y 1: "+y);
 y = x;
 System.out.println("y 2: "+y);
 System.out.println("x 2: "+x);
 }
 }

The results are;

y 1: BA
y 2: A
x 2: A
A,BA

I want to know why the last line of the result no equal to A,A?

[henry_78]

Hi,
Because u made a side effect on the StringBuffer b by the append().

[hardwired]

StringBuffer y is a copy of the reference to StringBuffer b. As long as the reference y continues to refer/point to this same StringBuffer, modifications in y will affect b. When you point y to another StringBuffer then modifications to y will no longer affect b.
See How Arguments Are Passed to Java Methods for discussion.

[oregon]

thanks
It was driving me crazy