Paul Grepps wrote:
>
> I expected the following to work since Objects are supposedly
> pass-by-reference. Am I doing something wrong here?
Yes :-)
> I'm just trying to change a Boolean value inside of a method and
> return as pass-by-reference to the caller.
in changeBoolean() you are not changing the state of the passed Boolean
object. Instead you're assigning something to the reference of the
object, which itself is a copy of the original reference.
Something like this would work:
public void changeBoolean(Boolean b) {
b.setValue(true);
}
but unfortunately objects of type Boolean are not mutable (you cannot
change the value of the wrapped boolean value).
I would suggest to write your own class (e.g. MutableBoolean or
BooleanHolder) which allows for changing of the wrapped type.
Regards, Oliver
> 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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