Question

我知道我的文档不是很棒。

这个程序是创建一个Rock，Paper，Scissors Game：

我最初努力让案例陈述与案例陈述正常工作，但我觉得我解决了这个问题。

我的问题：这是在switch语句中嵌套switch语句的可接受实现。否则，我可以在userChoice Switch语句中添加if语句。

public static void main(String[] args) {

    // Variable declarations
    Scanner keyboard = new Scanner(System.in);
    Random rand = new Random();
    int sentinel = 4;
    int userChoice;
    int computerChoice;

    // Display Rock, Paper, Scissors menu
    menu();

    // Obtain user's choice
    userChoice = validOption("\nPlease make a selection: ", 1, 4);

    // Display game results
    while (userChoice != sentinel) {
        switch (userChoice) {
            case 1:
                // Generate computer's choice
                computerChoice = rand.nextInt(3) + 1; 
                System.out.println("Computer's choice: " + computerChoice);

                // Determine outcome of the round
                switch (computerChoice) {
                    case 1:
                        System.out.println("Rock cannot defeat Rock. Draw.");
                        break;
                    case 2:
                        System.out.println("Paper covers Rock. Computer wins.");
                        break;
                    case 3:
                        System.out.println("Rock smashes Scissors. You win!");
                        break;
                }
                // Display menu selection and obtain user choice
                menu();
                userChoice = validOption("\nPlease make a selection: ", 1, 4);
                break;

            case 2: 
                // Generate computer's choice
                computerChoice = rand.nextInt(3) + 1; 
                System.out.println("Computer's choice: " + computerChoice);

                // Determine outcome of the round
                switch (computerChoice) {
                    case 1:
                        System.out.println("Paper covers Rock. You win!");
                        break;
                    case 2:
                        System.out.println("Paper cannot defeat Paper. Draw.");
                        break;     
                    case 3:
                        System.out.println("Scissors cut Paper. Computer wins.");
                        break;
                }
                //Display menu selection and obtain user choice
                menu();
                userChoice = validOption("\nPlease make a selection: ", 1, 4);
                break;

            case 3:
                // Generate computer's choice
                computerChoice = rand.nextInt(3) + 1; 
                System.out.println("Computer's choice: " + computerChoice);
                // Determine outcome of the round
                switch (computerChoice) {
                    case 1:
                        System.out.println("Rock smashes Scissors. Computer wins.");
                        break;
                    case 2:
                        System.out.println("Scissors cut Paper. You win!");
                        break;
                    case 3:
                        System.out.println("Scissors cannot defeat Scissors. Draw.");
                        break;
                }
                // Display menu selection and obtain user choice
                menu();
                userChoice = validOption("\nPlease make a selection: ", 1, 4);
                break;
        }
    }     
    System.out.println("Game Over.");
}

// Create menu method
public static void menu () {
    System.out.println("\n1 = Rock");
    System.out.println("2 = Paper");
    System.out.println("3 = Scissors");
    System.out.println("4 = End Game\n");
}

/**
 * Protects option input from incorrect value (non-numeric, too high or too low)
 * @param prompt
 * @param minValue
 * @param maxValue
 * @return 
 */
public static int validOption (String prompt,
                                int minValue,
                                int maxValue) {
    Scanner keyboard = new Scanner (System.in);
    int value;
    String errorMessage = "Incorrect value. Please select options "
            + "1, 2, 3 or 4\n";
    do {
        System.out.print(prompt);
        if (keyboard.hasNextInt()) {
            value = keyboard.nextInt();
            if (value < minValue || value > maxValue) {
                System.out.println(errorMessage);
            } else {
                break; // Exit loop.
            }
        } else {
            System.out.println(errorMessage);
        }
        keyboard.nextLine(); // Clears buffer.
    } while (true);
    return value;
}

}

Answer 1

恕我直言，只要它是可读的，在switch语句中编写switch语句本身就是好的。为了使代码更具可读性，您可以使用常量而不是1,2,3来引用选项：

[101100, 'hello']
[101101, 'twenty']

您的开关可能如下所示：

final int ROCK = 1;
final int PAPER = 1;
final it SCISSORS  = 1;

您可以改进的另一件事是将这两部分移出外部开关：

switch (computerChoice) {
    case ROCK:
        System.out.println("Rock cannot defeat Rock. Draw.");
        break;
    case PAPER:
        System.out.println("Paper covers Rock. Computer wins.");
        break;
    case SCISSORS:
        System.out.println("Rock smashes Scissors. You win!");
        break;
}

因为你在每种情况下都这样做。

您还可以将内部switch语句解压缩为如下方法：

// Generate computer's choice
computerChoice = rand.nextInt(3) + 1; 
System.out.println("Computer's choice: " + computerChoice);

// and

menu();
userChoice = validOption("\nPlease make a selection: ", 1, 4);

您的开关将如下所示：

private static handlePlayerRock() {
    // add the inner switch for the case ROCK of the outer switch here
}

private static handlePlayerScissors() {
    // add the inner switch for the case SCISSORS of the outer switch here
}

private static handlePlayerPaper() {
    // add the inner switch for the case PAPER of the outer switch here
}

除了嵌套交换机之外，还有更多高级方法可用于解决此问题。您可以将所有可能性放入switch (userChoice) { case ROCK: handlePlayerRock(); case PAPER: handlePlayerPaper(); case SCISSORS: handlePlayerScissors(); }，其中HashMap<Combination, String>是表示玩家和计算机选择的类。地图将包含以下内容：

Combination

您可以使用计算机和玩家的选择来访问与密钥相关联的值。

Answer 2

是的，您对嵌套switch语句的实现是正确的。 break语句在嵌套的switch语句中至关重要，因为它告诉Java程序找到了正确的选择并且程序可以继续而不必执行switch case语句中列出的其他选项，并且已经放置了所有的break声明正确。希望这很有帮助。

在switch语句中使用switch语句是否可以接受？

2 个答案: