this is from the practice exam1, the answer is D, i thought it was B.
isn't Wrappers are immutable, and i and i2 both uses the int 420 in the pool.
i actually tested it out.

If you change in your example to you get false. In the K & B book it says on page 246 that if you compare (with ==) two wrapper object of type Integer with the same values then you get true when the common value is between -128 and 127.

if wrapper1 and wrapper2 corresponding wrapper classes containing same primitive values then it is always the case that wrapper1 == wrapper2 as true when a char in the range \u0000 to \u007f(0-127), and remaining primitive numbers between -128 and 127.