break和continue跳出多重循环

关于break和continue，众所周知，break是跳出当前循环，continue是跳出本次循环。
但是在多重循环中，我们可能会模糊概念：break是跳出全部循环还是只是某层循环？–>跳出的是break所在层的循环即当前循环。
结论：只要记住，break和continue只对当层循环有用，对外层循环没有影响。

跳出单层循环：

例：

public static void main (String args[]) {
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                if (j == 2) break;
                System.out.println("i = " + i + "; j = " + j);
            }
        }
        System.out.println("==============");
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                if (j == 2) continue;
                System.out.println("i = " + i + "; j = " + j);
            }
        }
    }

结果：

i = 0; j = 0
i = 0; j = 1
i = 1; j = 0
i = 1; j = 1
i = 2; j = 0
i = 2; j = 1
i = 3; j = 0
i = 3; j = 1
==============
i = 0; j = 0
i = 0; j = 1
i = 0; j = 3
i = 1; j = 0
i = 1; j = 1
i = 1; j = 3
i = 2; j = 0
i = 2; j = 1
i = 2; j = 3
i = 3; j = 0
i = 3; j = 1
i = 3; j = 3

如何直接跳出多层循环：

可以在外层循环前面定义一个标号，然后在内层循环中使用带有标号break或者continue的语句，就可以直接跳出多重循环。
例：

public static void main (String args[]) {
    grade1:
    for (int i = 0; i < 4; i++) {
        for (int j = 0; j < 4; j++) {
            if (j == 2) break grade1;
            System.out.println("i = " + i + "; j = " + j);
        }
    }
    System.out.println("==============");
    grade2:
    for (int i = 0; i < 4; i++) {
        for (int j = 0; j < 4; j++) {
            if (j == 2) continue grade2;
            System.out.println("i = " + i + "; j = " + j);
        }
    }
}

结果：continue的效果有点和之前的break类似，意思是继续从grade2开始。

i = 0; j = 0
i = 0; j = 1
==============
i = 0; j = 0
i = 0; j = 1
i = 1; j = 0
i = 1; j = 1
i = 2; j = 0
i = 2; j = 1
i = 3; j = 0
i = 3; j = 1