java在for循环中，增量整数不会增加2

Question

这是我的密码

for (int i = 0; i<shots.size(); i=i+2){ //I would expect "i" to increase by 2 for every loop.
            i = i%4; //On this line, there is ALWAYS that i==2
            switch (i){
            case 0: boards[1].getTile(shots.get(i),shots.get(i+1)).shoot();
                break;
            case 2: boards[0].getTile(shots.get(i),shots.get(i+1)).shoot();
                break;
            }
            if (gameOver()){
                break;
            }
        }

但是，当我运行调试器时，每次我点击循环初始值设定项时，我都会看到“I”被重置为0，然后循环中第一行的“I”被设置为“2”。我希望它的行为像一个常规的for循环，只是我希望每次迭代“I”增加2而不是1。我有办法做到吗

谢谢你的帮助

Answer 1

我怀疑这是你的问题

 i = i%4;

让我们看看i的作用：

i = 0 is 0
i = i % 4 is the remainder of 0 / 4 which is 0
i = i + 2 is 2
i = i % 4 is the remainder of 2 / 4 which is 2
i = i + 2 is 4
i = i % 4 is the remainder of 4 / 4 which is 0

因此，除非shots.size()小于2，否则你将永远循环，除非gameOver()变为真，你将打破循环。你可以按照@Eran的建议去做 并创建一个新的int j作为i的mod，或者（因为您没有在其他任何地方使用j），只需执行以下操作：

switch (i%4)

Answer 2

我认为你需要两个变量：

    for (int i = 0; i<shots.size(); i=i+2){
        int j = i%4; // j will always be either 0 or 2, so the switch statement
                     // will toggle between the two cases
        switch (j){
        case 0: boards[1].getTile(shots.get(i),shots.get(i+1)).shoot();
            break;
        case 2: boards[0].getTile(shots.get(i),shots.get(i+1)).shoot();
            break;
        }
        if (gameOver()){
            break;
        }
    }

要使其工作，shots.size()必须是偶数。如果是奇数shots.get(i+1)最终将抛出异常