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我正在尝试为初学者 Java 类编写一个具有规范的程序。代码如下。有一行没有在第一个内部编译大约 30 行，以便查看附近的第一个 do while 循环。

分数[i + 1][i] = input.nextDouble();

这正是这行代码。它不会编译，也不会给出任何错误，所以我不知道我做错了什么。我现在有点茫然，可以用第二双眼睛。只是为了解释我做错了什么，以便我可以修复它以及我应该如何识别它。

这些是本作业的规格 ******************************************* ******************************。菜单系统可以选择输入下一个学生的成绩。按下后，用户将输入该学生参加了多少次考试。然后程序将要求用户输入每个考试成绩。菜单将有一个选项显示学生的考试平均成绩。菜单将具有按考试显示考试平均值的选项。菜单将有一个选项来显示所有考试的当前班级平均值。****************************************************** ***********************。

import java.util.*;

public class JaggedArray {


public static void main (String[ ] args) {
    int numStudents = 0, count = 0, x = 7;
    int numGrades = 0;
    String choice = "";
    int vId[];
    double score[ ][ ] = null;
    Scanner input = new Scanner (System.in);

    System.out.println("Welcome. How many students do you want to record grades for today?");

    numStudents = input.nextInt();
    vId = new int[numStudents];
    for (int s = 0; s < vId.length; s++) {
        System.out.println("Please enter the students class ID.");

        vId [s] = input.nextInt();

        System.out.println("How many exam grades would you like to record for this student?");

        numGrades = input.nextInt();
        do {
            System.out.println("Enter all exams taken for this student.");
            for (int i = 0; i < numGrades; i++)     {           
                System.out.print("\tSTUDENT # " + (count + 1) + " \tEXAM # " + (i + 1) + " : ");
                score[i + 1][i] = input.nextDouble();
            }
            count++;
            System.out.println("Is there additional students you would like to add? (y/n) : ");
            input.nextLine().toLowerCase();
            choice = input.nextLine(); 
            } while (choice.equals("y"));

        }


    //menu loop
    do {
        try {   //will try and catch to prevent input error by user, sets x to different value if correct
        System.out.println("*****************MENU*****************");
        System.out.println("1.\t Display the average of all exams by each Student ID.");
        System.out.println("2.\t Display the average of each exam by Exam #.");
        System.out.println("3.\t Display the current class average for all exams for all students.");
        System.out.println("**************************************");
        System.out.println("\n");
        System.out.print("Please enter your choice: ");
        int menuOption = input.nextInt();

        //average of all exams by student
            if (menuOption == 1) {
                for (int i = 0; i < count; i++) {
                    int studentSum = 0;
                    for (int j = 0; j < numGrades; j++) {
                        studentSum += score[i][j];
                    }   //end of inner for loop
                    double studentAvg = (double) studentSum / numGrades;
                    System.out.println("\nStudent #" + (i + 1) + " : " + studentAvg + "\n");
                }   //end of outer for loop

                //average of all exams by exam #
            } else if (menuOption == 2) {
                for (int i = 0; i < numGrades; i++) {
                    int examSum = 0;
                    for (int j = 0; j < count; j++) {
                        examSum += score[j][i];
                    }   //end of inner for loop
                    double examAvg = (double) examSum / numGrades;
                    System.out.println("\nExam #" + (i + 1) + " : " + examAvg + "\n");
                }   //end of outer for loop

                //current class average for all exams for all students
            } else if (menuOption == 3) {
                int classSum = 0;
                for (int i = 0; i < count; i++) {
                    for (int j = 0; j < numGrades; j++) {
                        classSum += score[j][i];
                    }   //end of inner for loop
                }   //end of outer for loop

                double classAvg = (double) classSum / (numGrades * count);
                System.out.println("\nAverage : " + classAvg + "\n");
            } else {
                System.out.println("Invalid choice");
            }   //end of  if-else statement

            //ask to select from menu again
            System.out.print("Would you like to continue (y/n) : ");
        input.nextLine().toLowerCase();
        choice = input.nextLine();
        x = 1;
        }   // end try and on to catch
        catch (Exception e) {
            System.out.println("Sorry, you can't do that. Try again.");
        }   // end catch
        }   // end do-while
     while (choice.equals("y") && (x == 1));
    System.out.println("Thank you!");
    }   //end of main
}   //end of class
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