Modifying object collections

Question

I'm working in some Java code and I have a doubt. I have a loop that goes along a Collection to modify each one of its objects with a method. The thing is, when you pass an object to a method, what are you really passing? A copy of the reference? the memory address? Here is my code:

for(Iterator it = colDesglosesBDI.iterator(); it.hasNext();)
{    
    DesgloseBDIVO desgloseBDI = (DesgloseBDIVO)it.next();
    desgloseBDI = completeDesgloseAgrup(desgloseBDI);
}

The method completeDesgloseAgrup returns a DesgloseBDIVO Object so I can replace the old objects with the new attributes. But maybe I can do it by this way:

for(Iterator it = colDesglosesBDI.iterator(); it.hasNext();)
{    
    DesgloseBDIVO desgloseBDI = (DesgloseBDIVO)it.next();
    completeDesgloseAgrup(desgloseBDI);
}

And in this case the method would be void and do not return any object. Is possible to do it in that way?

Regards

Answer 1

Yes that is entirely possible provided the completeDesgloseAgrup() method only changes the attributes of the argument, and does not try to replace it with a new object.

Consider this:

public void completeDesgloseAgrup( DesgloseBDIVO d )
{
    // will work, callee will see "something"
    d.setSomething( "something" );
}

public void completeDesgloseAgrup( DesgloseBDIVO d )
{
    // Won't work, as Java has call by value semantics. Callee won't see the new DesgloseBDIVO in callee's scope.
    d = new DesgloseBDIVO()
    d.setSomething( "something" );
}

Cheers,