如何在不使用label的情况下打破嵌套循环

Question

你好,这是我的代码.

int counter=0;

    for(int i=0;i<5;i++)
    {
        for(int j=0;j<5;j++)
        {
            System.out.println(++counter);
            if(counter==11)
                break;
        }
    }

我的问题是当计数器等于11时如何结束两个循环？在这个例子中,我只是结束第二个循环.我知道如果我使用标签有一种方法,但还有其他方法吗？提前致谢.

Answer 1

Answer 1

Well, you can do it like this by adding the condition into both for loops.

    for(int i=0;i<5 && counter!=11;i++)
    {
        for(int j=0;j<5 && counter!=11;j++)
        {
            System.out.println(++counter);
        }
    }

But you are violating the DRY principle and likely triggering an IDE/Sonar warning.

Answer 2

Add an exception to your class

private static class LoopDoneException extends Exception { }

Now throw it:

    try {
        for(int i=0;i<5;i++)
        {
            for(int j=0;j<5;j++)
            {
                System.out.println(++counter);
                if (counter == 11) {
                    throw new LoopDoneException();
                }
            }
        }
    } catch (LoopDoneException e) {
        // expected
    }
}

Answer 3

On reflection, I think teh best approach is a break statement referring to the label out.

    out:
    for (int i = 0; i < 5; i++) {
        System.out.println("outer loop");
        for (int j = 0; j < 5; j++) {
            System.out.println("inner loop: " + ++counter);
            if (counter == 11) {
                break out;
            }
        }
    }

Answer 2

只需在外循环中有一个标志和条件,最初它被设置为false.一旦满足您的条件,只需将标志设置为true即可.所以外部for循环条件失败并退出.

boolean isDone = false;
int counter=0;

for(int i=0;i<5 && !isDone; i++)
{
    for(int j=0;j<5;j++)
    {
        System.out.println(++counter);

        if(counter==11){
            isDone = true;
            break;
        }
    }
}