java - 将 Java 增量远远超过最大值时的行为

Question

考虑:

long n = Long.MAX_VALUE;
++n;

对于我的 JVM，这会返回到 Long.MIN_VALUE。这是定义的行为吗？有些 JVM 会抛出异常吗？

Answer 1

来自 JLS:

If an integer addition overflows, then the result is the low-order bits of the mathematical sum as represented in some sufficiently large two's-complement format. If overflow occurs, then the sign of the result is not the same as the sign of the mathematical sum of the two operand values.

来源:http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.18.2