java - 为什么我的嵌套 for 循环不显示 Hello World 2

Question

这是我的嵌套 for 循环。

int c = 1;
for (int d = 0; d < 10; d++) {
    if (c == 6) {
        System.out.println("Hello World 1");
    } else if (c == 7) {
        System.out.println("Hello World 2");
    }
    for (int e = 0; e < 5; e++) {
        System.out.println("This is the nested for loop :" +c);
        c++;
    }
}

这是我的控制台打印出来的内容。

This is the nested for loop :1
This is the nested for loop :2
This is the nested for loop :3
This is the nested for loop :4
This is the nested for loop :5
Hello World 1
This is the nested for loop :6
This is the nested for loop :7
This is the nested for loop :8

它会继续打印直到达到 50 并且不显示 Hello World 2。

Answer 1

让我向您当前的代码添加注释。按顺序执行步骤 1 到 7 来阅读此代码。

int c = 1;
for (int d = 0; d < 10; d++) {
    // 1. When we are here for the first time, c = 1, both if are false
    // 4. Now, c is equal to 6 so the first if is true, "Hello World 1" is printed
    // 7. Now, c is equal to 11, both if are false, nothing is printed...
    if (c == 6) {
        System.out.println("Hello World 1");
    } else if (c == 7) {
        System.out.println("Hello World 2");
    }
    for (int e = 0; e < 5; e++) {
        // 2. We reach here, c is incremented 5 times.
        // 5. c is incremented again 5 times
        System.out.println("This is the nested for loop :" +c);
        c++;
    }
    // 3. When we're here, c that was 1 is now 6 (incremented 5 times in step 2)
    // 6. When we're here for the second time, c is now 11 (6 incremented 5 times in step 5)
}

基本上，在第一个 for 的开头，c 是 1，然后是 6，然后是 11...但永远不会是 7，所以 “Hello World 2" 永远不会被打印。