The remainder operation for operands that are integers after binary numeric promotion (§5.6) produces a result value such that (a/b)*b+(a%b) is equal to a.
This identity holds even in the special case that the dividend is the negative integer of largest possible magnitude for its type and the divisor is -1 (the remainder is 0).
It follows from this rule that the result of the remainder operation can be negative only if the dividend is negative, and can be positive only if the dividend is positive. Moreover, the magnitude of the result is always less than the magnitude of the divisor.
# 1 楼答案
这在Java language specification section 15.17.3中有详细介绍
因此，例如，
-4 % 8确实是-4，但是由于4/-8是0，并且0 * -8 == 0，剩余的4 % -8必须是4