Question

In the code below, given that amethod has been called. At what point/line is the Object originally referenced by myObject, eligible for Garbage Collection?

class Test {
  private Object classObject;

  public void amethod() {
    Object myObject = new Object();
    classObject = myObject;
    myObject = null;
  }
}

And if classObject or amethod had an access modifier of public, protected, default or static, would it affect what point the Object is eligible for Garbage Collection? If so, how would it be affected?

• My first thought is that the Object is eligible for Garbage Collection when the Test object is eligible for Garbage Collection.
• But then again. The optimizer may know that the classObject is never read from in which case classObject = myObject; would be optimized out and myObject = null; is the point it is eligible for Garbage Collection.

Answer 1

The object will not become a candidate for garbage collection until all references to it are discarded. Java objects are assigned by reference so when you had

   classObject = myObject;

You assigned another reference to the same object on the heap. So this line

   myObject = null;

Only gets rid of one reference. To make myObject a candidate for garbage collection, you have to have

  classObject = null;