随机数（1-100）拣选循环程序|了解方法

Question

我要做的是创建一个程序，该程序将随机选择一个1到100之间的整数。然后，请用户猜测一下。循环直到他们这样做，并且在每次错误的猜测之后告诉他们它们太高还是太低。我想使用两种不同的方法来验证其输入。一个用于测试它是否为有效的int，另一个用于测试范围（1-100）。此秒将需要另一个参数作为高范围值。

我遇到的问题：

1。我不明白为什么在触发while (guess != a) {之前必须多次输入数字。

控制台示例：

I am thinking of a number from 1 to 100 ... guess what it is ?6
I am thinking of a number from 1 to 100 ... guess what it is ?6
I am thinking of a number from 1 to 100 ... guess what it is ?6
6
higher!

2。我该如何使用我的检查方法并使它们与我的while猜测循环有关？

再次从控制台示例：

`I am thinking of a number from 1 to 100 ... guess what it is? 10001
I am thinking of a number from 1 to 100 ... guess what it is? 10001
Error! Must be less than 100
I am thinking of a number from 1 to 100 ... guess what it is? 10001
100
lower!
10001
lower!`

{我目前所写的内容}

package labbs;

import java.util.Scanner;

public class Lab12 {

    public static double getDoubleGreaterThan(double low, Scanner input, String prompt) {
        double num;
        num = getDouble(input,prompt);
            if(num <= low)
            System.out.println("Error! Must be greater than 1");
            num = getDouble(input,prompt);    
                if (num > 100)
                System.out.println("Error! Must be less than 100");
                num = getDouble(input,prompt);


        return num;
    }

        public static double getDouble(Scanner input, String prompt) {
            boolean OK;
            double val=0;
            do {
                System.out.print(prompt);
                OK = true;
                try {
                    val = input.nextDouble();
                }
                catch(Exception e) {
                    OK = false;
                    System.out.println("Error! Invalid input. Must be a double value");
                    input.next();
                }
            }while(! OK);

            return val;

    }

    public static void main(String args[]) {

        Scanner keyboard = new Scanner(System.in);

        double output, letscheck;
        int count=0, guess=0;
        int a=1 + (int) (Math.random() * 99);

        letscheck = getDoubleGreaterThan(-0.9, keyboard,"I am thinking of a number from 1 to 100"
                + " ... guess what it is ?");


        while (guess != a) {
            guess = keyboard.nextInt();
            count++;
            if (guess > a) {
                System.out.println("lower!");
            } else if (guess < a) {
                System.out.println("higher!");
            }
        }
        System.out.println("Congratulations. You guessed the number with "
                + count + " tries!");

    }

}

Answer 1

1。查询：您刚刚错过了getDoubleGreaterThan()方法中的括号，因为如果语句块始终无法在输入的基础上正常工作，请按如下所示更改代码：

public static double getDoubleGreaterThan(double low, Scanner input, String prompt) {
            double num;
            num = getDouble(input,prompt);
                if(num <= low){
                System.out.println("Error! Must be greater than 1");
                num = getDouble(input,prompt);
                }
                    if (num > 100){
                    System.out.println("Error! Must be less than 100");
                    num = getDouble(input,prompt);
                    }


            return num;
        }