Question

我已经使用Java很长一段时间了，但我的循环教育有点缺乏。我知道如何创建java中存在的每个循环，并打破循环。但是，我最近想过这个：

说我有两个嵌套循环。我可以仅使用一个break语句中断两个循环吗？

这是我到目前为止所拥有的。

int points = 0;
int goal = 100;
while (goal <= 100) {
    for (int i = 0; i < goal; i++) {
        if (points > 50) {
           break; // For loop ends, but the while loop does not
        }
        // I know I could put a 'break' statement here and end
        // the while loop, but I want to do it using just
        // one 'break' statement.
        points += i;
    }
}

有没有办法实现这个目标？

Answer 1

在Java中，您可以使用标签指定要中断/继续的循环：

mainLoop:
while (goal <= 100) {
   for (int i = 0; i < goal; i++) {
      if (points > 50) {
         break mainLoop;
      }
      points += i;
   }
}

Answer 2

是的，你可以写break with label例如：

int points = 0;
int goal = 100;
someLabel:
while (goal <= 100) {
   for (int i = 0; i < goal; i++) {
      if (points > 50) {
         break someLabel;
      }
   points += i;
   }
}
// you are going here after break someLabel;

Answer 3

有很多方法可以给这只猫上皮。这是一个：

int points = 0;
int goal = 100;
boolean finished = false;
while (goal <= 100 && !finished) {
   for (int i = 0; i < goal; i++) {
      if (points > 50) {
         finished = true;
         break;
      }
   points += i;
   }
}

更新：哇，不知道打破标签。这似乎是一个更好的解决方案。

Answer 4

小学，亲爱的沃森......

int points = 0;
int goal = 100;

while (goal <= 100) {
  for (int i = 0; i < goal; i++) {
    if (points > 50) {
      goal++;
      break;
    }
  points += i;
  }
}

或

int points = 0;
int goalim = goal = 100;

while (goal <= goalim) {
  for (int i = 0; i < goal; i++) {
    if (points > 50) {
      goal = goalim + 1;
      break;
    }
  points += i;
  }
}

Answer 5

您可以重置循环控制变量。

select 
  name, type 
from 
  mysql.proc 
where 
  db = database() 
order by 
  type, name;

Answer 6

You shouldn't use labels in objective language. You need to rewrite the for/while condition.

So your code should look like:

int points = 0;
int goal = 100;
while (goal <= 100 && points <= 50) {
    for (int i = 0; i < goal && points <= 50; i++) {
        points += i;
    }
}

// Now 'points' is 55

如何退出两个嵌套循环？

6 个答案: