带增量运算符的Java Switch语句

Question

int k=0;

switch (k++) {
   case 0: System.out.println("0 is "+k);
}

Output:

0 is 1

Why 1? It's still in switch operator and must be incremented after exit from it.

Answer 1

Postfix means it will be incremented after evaluation, NOT after the current block. In this case it's evaluated, increments k, then branches to the evaluation. Exactly as it should.

Answer 2

The first thing the switch statement does is process the expression (k++) . The result returned is compared to the case value(s). But since k++ has already been processed, k has the value of 1 . Since it is a postfix operator, the value returned is the value before it was incremented. Thus 0 is returned, though the value after the expression is executed is 1 .