java如何将比较if语句转换为switch case语句？

Question

我是java编程新手，很难弄明白这一点

这是我的密码：

boolean running = true;
   PANTS:
while (running) {
    int waistMeasure = in.nextInt();

    if (waistMeasure >= 26 && waistMeasure < 28){
        System.out.println("You are a Small.");
        break;
    }
    if (waistMeasure >= 28 && waistMeasure < 30){
        System.out.println("You are a Medium.");
        break;
    }
    if (waistMeasure >= 30 && waistMeasure <= 34){
        System.out.println("You are a Large.");
        break;
    }

    else {
        System.out.println("Invalid input");
    }
}

有没有办法将其转换为switch case语句

Answer 1

是的，有——但是你必须为每个值创建一个case（如下所示）。不能用单个case来表示一系列值。因此，如果你想要可读和可维护的代码，你应该坚持使用ifs

switch (waistMeasure) {
case 26:
case 27:
    System.out.println("You are a Small.");
    running = false;
    break;
case 28:
case 29:
// ....
}

Answer 2

你是说这样的吗

请注意，必须为break语句使用PANTS标签才能退出循环，否则它们将从switch中断并继续循环

PANTS: for (;;) {
    int waistMeasure = in.nextInt();
    switch (waistMeasure) {
        case 26:
        case 27:
            System.out.println("You are a Small.");
            break PANTS;
        case 28:
        case 29:
            System.out.println("You are a Medium.");
            break PANTS;
        case 30:
        case 31:
        case 32:
        case 33:
        case 34:
            System.out.println("You are a Large.");
            break PANTS;
        default:
            System.out.println("Invalid input");
    }
}

Answer 3

switch (waistMeasure) {
    case 26:
    case 27:
        System.out.println("You are a Small.");
        break PANTS;
    case 28:
    case 29:
        System.out.println("You are a Medium.");
        break PANTS;
    case 30:
    case 31:
    case 32:
    case 33:
    case 34:
        System.out.println("You are a Large.");
        break PANTS;
    default
        System.out.println("Invalid input");
}