Java Integer Caching: The == Operator Mystery

Added: 2026-04-29

In Java, the == operator compares object references, not values. Java caches Integer objects for values between -128 and 127, so when two Integer variables are assigned values within this range, they reference the same cached object and == returns true. However, for values outside this range (like 128), new Integer objects are created for each assignment, resulting in different references and causing == to return false. This is why Integer a = 128, b = 128; a == b evaluates to false.