Hi Paul,
"objects are passed by reference" is only half of the truth. In fact,
this is implemented by passing the reference to the object (in C you
would call it a pointer) by value. Your parameter Boolean b in
changeBoolean() is this reference. By assigning to the reference, this
reference will furthermore reference (point to in C-speak) another
object. The object itself, of course, is not changed. To change the
object, it has to have a method to influence its internal state. In case
of a Boolean object, a meaningful method would be setValue(boolean). For
security reasons and to make Boolean objects as similar as possible to
the native type boolean, such a method does not exist.
Matthias
Paul Grepps wrote:
>
> I expected the following to work since Objects are supposedly
> pass-by-reference. Am I doing something wrong here?
>
> I'm just trying to change a Boolean value inside of a method and
> return as pass-by-reference to the caller.
>
> My environment is:
> Blackdown JDK1.2 pre2, RedHat 6.1, glibc 2.1.2
>
> The output of the following program is:
> Boolean before: false
> changeBoolean(): false
> changeBoolean(): true
> Boolean after: false
>
> I expected the Boolean after: to be true.
>
> ----------------------------------------------------------------------
>
> public class BooleanTest2 {
> public void changeBoolean(Boolean b) {
>
> System.out.println("changeBoolean(): " + b.booleanValue());
> b = Boolean.TRUE;
> System.out.println("changeBoolean(): " + b.booleanValue());
> }
>
> public static void main(String args[])
> {
> BooleanTest2 bt = new BooleanTest2();
> Boolean bool = new Boolean(false);
>
> System.out.println("Boolean before: " + bool.booleanValue());
> bt.changeBoolean(bool);
> System.out.println("Boolean after: " + bool.booleanValue());
> }
> }
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