Question

I have 2 lists and am a little confused about adding an object into both of them like this:

TestClass e;
List lst1;
LinkedList lst2;
...
lst1.add(e);
lst2.add(e);

Will lst1 and lst2 have copies of e? or the reference to the same object e?
If the first is true, how can the code make copies of e if TestClass is not clonable?

Answer 1

Will lst1 and lst2 have copies of e?

Yes.

Both lists will have a copy of the value contained in e. (Note though, that e contains a reference and not an actual object.)

This means that

1. Both lists will have one copy each of the reference to the TestClass object which e refers to at the point of the add.

2. Changes to the TestClass object will be visible from both lists references.

3. Performing e = null after the add will not affect the content of the lists (the lists contain copies, remember? 😉