Should object be explicitly deleted after removing it from a Vector?

Question

Let's say I have a Vector v that contains 100 objects of class Scenario which is composed of 10 different types of objects.In order to permanently delete Scenario and all its objects at index 5 of Vector v , which one of the following is correct way.

1.   v.removeElementAt(5);

OR:

2.   Scenario s=(Scenario) v.elementAt(5); 
     v.removeElementAt(5);
     s=null;

OR:

3.   Scenario s=(Scenario) v.elementAt(5); 
     s.makeAllObjectsNull();//explicitly assign null to 10 objects inside Scenario e.g. object1=null object2=null and so on
     v.removeElementAt(5);
     s=null;

Answer 1

Does an object need to be explicitly deleted after deleting it from a Vector? in simple word, all object that haven't any reference from another object is legible to be GC.

So any case of your code get that condition, then the object will be GC.

for example if a Scenario object has only referent from that vector, then:

v.removeElementAt(5);

the only reference has gone, and it will be legible to be GC.

another thing to tell here. when you doing this:

 Scenario s = (Scenario) v.elementAt(5); 
 v.removeElementAt(5);
 s = null;

You just declared another reference s and then set it to null, so it's not necessary to this.