Explicit nulling

Question

In what situations in java is explicit nulling useful. Does it in any way assist the garbage collector by making objects unreachable or something? Is it considered to be a g

Answer 1

In general it isn't needed (of course that can depend on the VM implementation). However if you have something like this:

private static final Map foo;

and then have items in the map that you no longer need they will not be eligible for garbage collection so you would need to explicitly remove them. There are many cases like this (event listeners is another area that this can happen with).

But doing something like this:

void foo()
{
    Object o;

    // use o

    o = null; // don't bother doing this, it isn't going to help
}

Edit (forgot to mention this):

If you work at it, you should find that 90-95% of the variables you declare can be made final. A final variable cannot change what it points at (or what its value is for primitives). In most cases where a variable is final it would be a mistake (bug) for it to receive a different value while the method is executing.

If you want to be able to set the variable to null after use it cannot be final, which means that you have a greater chance to create bugs in the code.