java - 将范围保持在一组特定的数字内

Question

对于我的 Java 类，我正在编写一个小程序，它首先选择 1 到 100 之间的 int 数字。然后提示用户开始猜测正确的 int >。如果用户猜测的 int 值过高或过低，程序会打印出一个新的范围供他们猜测。如果用户输入一个String或一个double，程序只是重新要求用户输入一个int，但不改变范围反正。

示例输出(当 secret 数字为 20 时)如下所示:

c:\csc116> java GuessingGame Guess the secret number!Enter a number between 1 and 100 (inclusive): 45Enter a number between 1 and 44 (inclusive): jlkjEnter a number between 1 and 44 (inclusive): 31.0  //doubleEnter a number between 1 and 44 (inclusive): 1000 //outside the range of 1-100Enter a number between 1 and 44 (inclusive): 34Enter a number between 1 and 33 (inclusive): 15Enter a number between 16 and 33 (inclusive): 20    You win!

The program appears to be almost there, but with one exception. One of the requirements is that when a user types an int that is outside our given range of 1 and 100, the print out message does not change (as seen in example above). This is where I am getting stumped quite a bit, and am looking to see if anyone can help guide me to the correct answer.

import java.util.*;


public class GuessingGame {


    public static void main(String[] args) {
        introduction();
        Scanner console = new Scanner(System.in);
        Random rand = new Random();

        int guess = 0;
        int minimum = 1;
        int maximum = 100;
        int secretNumber = rand.nextInt(100) + 1;

        System.out.print("Enter a number between " + minimum + " and " + maximum + " (inclusive): ");
        while (guess != secretNumber) {
            if (console.hasNextInt()) {
                guess = console.nextInt();
                if (guess > secretNumber) {
                    maximum = guess - 1;
                    System.out.print("Enter a number between " + minimum + " and " + maximum + " (inclusive): ");
                }
                if (guess < secretNumber) {
                    minimum =guess + 1;
                    System.out.print("Enter a number between " + minimum + " and " + maximum + " (inclusive): ");
                }
                if (guess == secretNumber) {
                    System.out.println("You win!");
                }
            } else {
                console.next();
                System.out.print("Enter a number between " + minimum + " and " + maximum + " (inclusive): ");
            }
        }
    }


    public static void introduction() {
        System.out.println("Guess the secret number!");
    }
}

Answer 1

你有:

            guess = console.nextInt();
            if (guess > secretNumber) {
                maximum = guess - 1;
                System.out.print("Enter a number between " + minimum + " and " + maximum + " (inclusive): ");
            }
            if (guess < secretNumber) {
                minimum =guess + 1;
                System.out.print("Enter a number between " + minimum + " and " + maximum + " (inclusive): ");
            }
            if (guess == secretNumber) {
                System.out.println("You win!");
            }

现在您根本没有检查最小/最大范围。您必须为此添加显式检查，但需要注意的是(此处的其他答案中遗漏了)，您必须确保您不将输入视为猜测(如果输入已超出)的范围。您当前使用 if 而不使用 else 的风格意味着您在实现它时必须小心。您有几个选择，例如:

            guess = console.nextInt();
            if (guess < minimumAllowed || guess > maximumAllowed) {
                // handle error
            } else {
                // handle valid input
                if (guess > secretNumber) {        
                    // ...
                }
                if (guess < secretNumber) {
                    // ...
                }
                if (guess == secretNumber) {
                    // ...
                }
            }

或者:

            guess = console.nextInt();
            if (guess < minimumAllowed || guess > maximumAllowed) {
                // handle error
            } else if (guess > secretNumber) {        
                // ...
            } else if (guess < secretNumber) {
                // ...
            } else if (guess == secretNumber) {
                // ...
            }

或者，坚持您当前的风格，只要您不必在循环中执行任何更多不相关的逻辑(您的程序中似乎就是这种情况):

            guess = console.nextInt();
            if (guess < minimumAllowed || guess > maximumAllowed) {
                // handle error
                continue;
            }
            // handle valid input
            if (guess > secretNumber) {        
                // ...
            }
            if (guess < secretNumber) {
                // ...
            }
            if (guess == secretNumber) {
                // ...
            }