Why Long.toHexString(0xFFFFFFFF) returns ffffffffffffffff

Question

This is what I see in java, and it puzzles me.

Long.toHexString(0xFFFFFFFF) returns ffffffffffffffff

Similarly, 0xFFFFFFFF

Answer 1

As others have said, 0xFFFFFFFF evaluates to the int value -1, which is promoted to a long.

To get the result you were expecting, qualify the constant with the L suffix to indicate it should be treated as a long, i.e. Long.toHexString(0xFFFFFFFFL).