java - 循环在要求用户输入新输入之前执行所有操作，而不是仅仅按照应有的方式重新请求

Question

我最近被分配了一项作业，用不同的语言编写代码，这是我在 python 中使用的唯一语言。我的代码应该做的是要求用户输入，然后首先将其设置为高、低并开始计算平均值。

package hgp.pkg13.pkg16;

import java.util.Scanner;

public class HGP1316 {
    //Declaration of variables
    static int Running_total = 0;
    static double Average = 0.0;
    static int User_input = 0;
    static double counter = 0.0 ;
    static int Highest_input = -1;
    static int Lowest_input = -1; 

    public static void main(String[] args) {
        //Intro Program (Optional)
    {
        System.out.println("This program will give you the highest, lowest, and average of the integers you \n"
          + "enter. To end enter a negative number ");       
    }

    //2. Ask user to enter a positive integer (or a negative integer to stop)
    //3. Record the user's input
    //4. Test the input >= 0
    while (User_input >=0){
        Scanner user_input = new Scanner( System.in );
        Integer User_input;
        System.out.print("Please enter an integer: ");
        User_input = user_input.nextInt();
        //4a. If it is true that input >= 0
        if (User_input >= 0)
        {

            //4a1Add the input to "running total"
            Running_total = Running_total + User_input;
            //4a2. Increment "number of inputs counter"
            counter = counter + 1;  
            //4a3. Test if "number of inputs counter" is equal to 1
            if (counter == 1)
            {
                //4a31. If true, replace both "highest input" and "lowest input" with the input
                Highest_input = User_input;
                Lowest_input = User_input;
            }

            //4a5. If the input > "highest input" then replace "highest input" with input
           if (User_input > Highest_input)
           {
               Highest_input = User_input;
           }
           //4a6. If the input < "lowest input" then replace "lowest input" with input
           if (User_input < Lowest_input)
           {
               Lowest_input = User_input;
           }
           //4b. If false
           //4b1. Goto step 5
           else;
           {
               //5. Calculate average (formula: "running total" /"number of inputs counter" )
                Average = (Running_total / counter);
                //6. Display/communicate "highest input", "lowest input" and average
                System.out.println ("The Highest value entered was : "+ Highest_input);
                System.out.println ("The Lowest value entered was : " + Lowest_input);
                System.out.println("The Average of enteries was : "+ Average);
                //7. Terminate
                }
            }
        }
    }
}    

我现在遇到的问题是它遍历整个循环而不是重新请求用户输入。这可能与我的 {} 有关，但我不确定。

Answer 1

由于此代码中存在大量有害的编码约定和最佳实践，因此我将忽略其中大部分并专注于您的案例中重要的内容:

1. 你的代码永远不会跳出循环。这是因为您定义了static int User_input = 0;，然后在循环内定义了一个同名的变量，这会隐藏静态变量并存储用户输入。但是，在 while 条件中检查的是静态变量。
2. 您没有在应该打印的地方打印。首先，您有 else; ，它基本上什么也不做，因为它包含一个空语句。之后，您始终执行循环的其余部分。

这是“固定”代码:

public class HGP1316 {
    static int Running_total = 0;
    static double Average = 0.0;
    static int User_input = 0;
    static double counter = 0.0 ;
    static int Highest_input = -1;
    static int Lowest_input = -1;
    public static void main(String[] args) {
        {
            System.out.println("This program will give you the highest, lowest, and average of the integers you \n"
                    + "enter. To end enter a negative number ");
        }

        Scanner user_input = new Scanner( System.in );
        while (User_input >= 0) {
            System.out.print("Please enter an integer: ");
            User_input = user_input.nextInt();

            if (User_input >= 0)
            {
                Running_total = Running_total + User_input;
                counter = counter + 1;
                if (counter == 1)
                {
                    Highest_input = User_input;
                    Lowest_input = User_input;
                }

                if (User_input > Highest_input)
                {
                    Highest_input = User_input;
                }

                if (User_input < Lowest_input)
                {
                    Lowest_input = User_input;
                }
            } else {
                Average = (Running_total / counter);
                System.out.println ("The Highest value entered was : "+ Highest_input);
                System.out.println ("The Lowest value entered was : " + Lowest_input);
                System.out.println("The Average of enteries was : "+ Average);
            }
        }
        user_input.close();
    }
}