Does variable = null set it for garbage collection

Question

Help me settle a dispute with a coworker: Does setting a variable or collection to null in Java aid in garbage collection and reducing memory usage? If I have a long running

Answer 1

It is useless on local variables, but it can be useful/needed to clear up instance variables that are not required anymore (e.g. post-initialization).

(Yeah yeah, I know how to apply the Builder pattern...)

Answer 2

That could only make some sense in some scenario like this:

public void myHeavyMethod() {
  List hugeList = loadHugeListOfStuff();  // lots of memory used
  ResultX res = processHugeList(hugeList); // compute some result or summary 
  // hugeList = null;  // we are done with hugeList
    ...
  // do a lot of other things that takes a LOT of time (seconds?)
  // and which do not require hugeList
   ...
}

Here it could make some benefit to uncomment the hugeList = null line, I guess.

But it would certainly make more sense to rewrite the method (perhaps refactoring into two, or specifying an inner scope).