object a = object b; what happens to object a?

Question

One of my professor has given us a few practice questions for an exam, and one of the questions is something like the below (psuedocode):

a.setColor(blue);
b         


        

Answer 1

It's because the fact that in first example, a and b are objects so this is what happens in each of the steps:

a <-- is an object

b <-- is an object

a.setColor(blue); <-- a becomes blue

b.setColor(red); <-- b becomes red

a = b; <-- IMPORTANT:: original a object is released and available for garbage collection and now a holds the reference of b object, which mean a and b are referring the same object now, which is b.

b.setColor(purple); <-- b is purple now. Since a points to b only, a is also purple

Answer: Both a and b are purple at this point.