Are Integer, Boolean, etc. Java Objects singleton objects?

Question

I tried to search for this but couldn't find an answer easily.

If we have multiple Integer Java objects corresponding to the same integer value--are they the same in memory?

Answer 1

No, but if you use Integer.valueOf(), Long.valueOf(), etc you may get single cached values. Not the same thing.

Answer 2

Not unless you create them like this

Integer a = new Integer(5);
Integer b = a;
Integer c = b;

In the above case, a, b, and c, would all refer to the same Integer object.

If, on the other hand, you declare them like this

Integer a = new Integer(5);
Integer b = new Integer(5);
Integer c = new Integer(5);

then the 3 variables, a, b, and c all refer to separate Integer object.