Math.abs returns wrong value for Integer.Min_VALUE

Question

This code:

System.out.println(Math.abs(Integer.MIN_VALUE));

Returns -2147483648

Should it not return the absolute value as 2147483648 ?

Answer 1

Integer.MIN_VALUE is -2147483648, but the highest value a 32 bit integer can contain is [phone]. Attempting to represent [phone] in a 32 bit int will effectively "roll over" to -2147483648. This is because, when using signed integers, the two's complement binary representations of [phone] and -2147483648 are identical. This is not a problem, however, as [phone] is considered out of range.

For a little more reading on this matter, you might want to check out the Wikipedia article on Two's complement.