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

In Java, it's generally correct to think of any variable which is an Object as being a pointer to a value of that Object type. Therefore, the following in Java:

Color a = new Color(), b = new Color();

a.setColor(blue);
b.setColor(red);
a = b;
b.setColor(purple);
b = a;

Should do more or less the same thing as the following in C++:

Color *a = new Color();
Color *b = new Color();

a->setColor(blue); // the value a points to is now blue
b->setColor(red); // the value b points to is now red
a = b; // a now points to the same value as b.
b->setColor(purple); // the value BOTH a and b point to is now purple
b = a; // this does nothing since a == b is already true

(Note that this is NOT the same as references - as per this article).

Also note that, for primitives, Java variables are simply values - NOT pointers. So, in the case of primitive integers, it should behave more or less as you expect in your question, since a = b is setting the value of a equal to the value of b.