双for循环的观察

package pracTest;

public class Test {
    public static void main(String[] args) {
        for (int i = 1; i <= 5; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.println("i = " + i);
                System.out.println("j = " + j);
                System.out.println("  ");
            }
        }

    }

}

结果:

i = 1
j = 1

i = 2
j = 1

i = 2
j = 2

i = 3
j = 1

i = 3
j = 2

i = 3
j = 3

i = 4
j = 1

i = 4
j = 2

i = 4
j = 3

i = 4
j = 4

i = 5
j = 1

i = 5
j = 2

i = 5
j = 3

i = 5
j = 4

i = 5
j = 5

可以看出:在外层i确定后,内层j依次遍历输出.