java - 尝试计算使用 do-while 和 while 循环给出的输入的平均值，但它一直停止

Question

脚本的主要要点是不断询问成绩，直到用户输入负数。输入负数后，它会计算这些成绩的平均值。用户输入的成绩只能是4-10。

我已经花了几个小时试图解决这个问题。如果我只输入无效输入或只输入有效输入，它工作正常，但第二次我尝试将其混合时，脚本停止。

例如:如果我输入 4(有效输入)，脚本会要求另一个成绩。如果我输入 3(无效输入)，脚本会说输入无效并要求另一个有效输入。之后，如果我再次输入 4，它就会停止工作，而它应该会一直这样下去，直到我输入一个负数，它才会开始计算有效输入的平均值。

import java.util.Scanner;

public class Average {

public static void main(String[] args){

    Scanner scanner = new Scanner(System.in);

System.out.println("The program will calculate the average of the user inputted grades.");
System.out.println("The program will start calculating with any negative integer");

double grade;   
double sum = 0;
int count = 0;



do {
    System.out.print("Input grade (4-10): ");
    grade = scanner.nextDouble();

    if (grade >= 4 && grade <= 10){
        sum = sum + grade;
        count++; 
    }



} while (grade >= 4 && grade <= 10);

 {


while (grade >= 0 && grade < 4 || grade > 10){

    System.out.println("Invalid grade!");
    System.out.print("Input grade (4-10): ");
    grade = scanner.nextDouble();


    if (grade < 0){

        System.out.println(count + " grades were given.");
        System.out.println("Average: " + sum/count);
        break;
    }
  }
 }
} 

Answer 1

它不起作用，因为你的循环是分开的，所以如果 first 为假，则 second 只工作一次然后停止。尝试这样的事情:

import java.util.Scanner;

public class Average {

    public static void main(String[] args){

        Scanner scanner = new Scanner(System.in);

        System.out.println("The program will calculate the average of the user inputted grades.");
        System.out.println("The program will start calculating with any negative integer");

        double sum = 0;
        int count = 0;
        double grade;

        do{
            System.out.print("Input grade (4-10): ");
            grade = scanner.nextDouble();

            if(grade >= 4 && grade <= 10){
                    sum = sum + grade;
                    count++;
            }else{
                System.out.println("Invalid grade!");
            }
        }while(grade >= 0);

        System.out.println(count + " grades were given.");
        System.out.println("Average: " + sum/count);


    }
}