DZone

In an interview, one of my friends was asked: If we have two Integer objects, Integer a = 127; Integer b = 127; Why does a == b evaluate to true when both are holding two separate objects? In this article, I will try to answer this question and explain the answer.

You may also like:
 The Internal Cache of Integers

Short Answer

The short answer to this question is, direct assignment of an int literal to an Integer reference is an example of auto-boxing concept where the literal value to object conversion code is handled by the compiler, so during compilation phase compiler converts Integer a = 127; to Integer a = Integer.valueOf(127);.

Source: DZone