Assign an object to null [duplicate]

Question

If I instantiate an object and pass it to an function, in this function I assign this object to null. It seems when return from the function, the object still there.

I just want to know when I assign null, what happens.

Answer 1

You can never assign to an object. All you ever have are primitives and references. A reference is either null or a pointer to an object of suitable class.

Java arguments are passed by value. Your called method got a copy of a reference. It made that reference null. The calling method has its own reference which was unaffected by any assignments to the passed copy. That reference still points to the object.