java - 如何在循环中输入超过1个整数

Question

我有一个程序，允许用户从 4 个选项中进行选择:1 - 设置成绩百分比2 - 输入成绩3 - 获取平均值4 - 退出

程序运行顺利，没有编译错误，我能够选择每个选项并使文本行正确显示。

我的问题是，当用户选择选项2输入成绩时，如何在不执行的情况下输入超过1的成绩？目前，当您输入成绩时，按 Enter 键，它将带您返回主菜单，并且不允许您输入超过 1 的成绩。这是代码:

import java.util.Scanner;

public class ExerciseThree
{
public static void main ( String[] argsv )
{

    float percent = 0;
    double grade = 0;
    double totalAvg = 0;
    double total = 0;
    double gradeAvg = 0;

    int gradeCounter = 0;
    int quit;
    int choice = 0;

    Scanner input = new Scanner (System.in);


    while (choice != 4 ) 
    {

    System.out.println( "Please choose one of the following: \n 1 - Set percentage of total for new grades \n 2 - Enter new grades \n 3 - Get average \n 4 - Quit ");
    choice = input.nextInt();



        switch (choice)

        { 

            case 1:         
                System.out.println( "Enter a percentage to multiply by (Format: 10% = .10)" );
                percent = input.nextFloat(); 


            break;



            case 2:
                System.out.println( "Enter grades" );
                grade = input.nextDouble();
                total = total + grade;
                gradeCounter = gradeCounter + 1;
                gradeAvg = (double) total / gradeCounter;

            break;      



            case 3:
                System.out.println( "You have chosen to get the average" );
                totalAvg = totalAvg + percent * grade;
                totalAvg = input.nextDouble();          
            break;



            default: 
                System.out.println( "You have chosen to quit" );

            break; 


        }

    }


}

}

Answer 1

进行循环，直到输入停止字符(例如空白字符)

case 2:
            System.out.println( "Enter grades" );
            boolean isDone = false;
            while(isDone == false) {
               grade = input.nextDouble();
               if(grade == '') {
                  isDone = true;
                }
            }
            total = total + grade;
            gradeCounter = gradeCounter + 1;
            gradeAvg = (double) total / gradeCounter;