java - 错误表达式非法开始

Question

我不断得到:

illegal start of expression,';" expected System.exit(0), and reached end of file while parsing

这是对其预期功能和代码的描述。

要解决的问题:
我应该在课外学习多少内容？

问题:
你的同学需要帮助。这是他们进入大学的第一年，他们需要确定需要学习多少小时才能取得好成绩。

Study Hrs Per Week Per Credit                 Grade
5:                                            A,
4:                                            B,
3:                                            C,
2:                                            D,
0:                                            F,

项目规范:

1. 用户输入他们计划学习的小时数周或他们想要的成绩取决于他们的学分进入。 (注意:您的程序必须为用户提供这两个选项。)
2. 程序显示用户姓名、积分数、总积分学习时数以及他们应该获得的成绩。
3. 您可以使用简介中介绍的任何编程技术编程逻辑类(class)来完成这个项目。那将但是，要求您提前阅读教科书有关如何在 Java 中实现该技术的说明编程语言。

下面是我的代码:

import javax.swing.JOptionPane; //Needed for the dialogue box

/**
    This program shows the student the grade they will receive 
    or how much to study for a certain grade.
*/

public class MoultonAlainaProject1
{
    public static void main(String[] args)
    {
        string wantedGrade, desiredGrade, name, input;
        char finalGrade;
        int gradeA = 5;
        int gradeB = 4;
        int gradeC = 3;
        int gradeD = 2;
        int gradeF = 0;
        float studyHrs;
        int creditHrs, userChoice;

        //Scanner for keyboard input
        Scanner keyboard = new Scanner(System.in);

        name = JOptionPane.showInputDialog("Please enter your name.");

        input = JOptionPane.showInputDialog("How many credit hours do you plan on taking this semester?");
        creditHrs = integer.parseInt(input);

        input = JOption.showInputDialog("If you would like to know the amount of hours you should study for the amount of" + 
                                        "credit hours press 1. If you would like to know the grade you would receive by" +
                                        "entering the amount of hours you plan to study press 2.");
        userChoice = integer.parseInt(input);

        if (userChoice == 1)
        {
            desiredGrade = JOptionPane.showInputDialog("Enter the grade you would like to receive.");

            if (desiredGrade == 'A' || 'a')
            {
                wantedGrade = gradeA;
            }
            else
            {
                if (desiredGrade == 'B' ||'b')
                {
                    wantedGrade = gradeB;
                }
                else
                {
                    if (desiredGrade == 'C' || 'c')
                    {
                        wantedGrade = gradeC;
                    }
                    else
                    {
                        if (desiredGrade == 'D' || 'd')
                        {
                            wantedGrade = gradeD;
                        }
                        else
                        {
                            if (desiredGrade == 'F' || 'f')
                            {
                                wantedGrade = gradeF;
                            }
                            else 
                            {
                                System.out.printIn("Error: you have not entered a valid input.");
                            }
                        }
                    }   
                }
            }   

            studyHrs = wantedGrade * creditHrs; 
        }
    else
    {
        if (userChoice == 2)
        {
            input = JOptionPane.showInputDialog("Enter the amount of hours you plan to study a week.");
            studyHrs = integer.parseInt(input);

            wantedGrade = studyHrs/creditHrs;

            if (wantedGrade >= 5)
            {
                finalGrade = "A";
            }
            else
            {
                if (wantedGrade >= 4)
                {
                    finalGrade = "B";
                }
                else 
                {
                    if (wantedGrade >= 3)
                    {
                        finalGrade = "C";
                    }
                    else
                    {
                        if (wantedGrade >= 2)
                        {
                            finalGrade = "D";
                        }
                        else
                        {
                            if (wantedGrade < 2)
                            {
                                finalGrade = "F";
                            }
                        }
                    }
                }
            }

        JOptionPane.showMessageDialog(null, name+ ", you are taking " +creditHrs+ "credit hours, you should study " +studyHrs+ " hours a week to receive " +finalGrade+ " in your classes." 

        System.exit(0);
    }
}   

我已经检查过大括号很多次了，但我可能在某个地方漏掉了一些东西

Answer 1

您有大约 20 个编译时错误。
我看到缺少导入、用小写、未闭合括号编写的字符串，
未闭合的大括号、将字符串值分配给 char 变量等
请参阅下文并修复它们。

    Description Resource    Path    Location    Type
    Type mismatch: cannot convert from String to char   MoultonAlainaProject1.java  /TEST/src   line 107    Java Problem
    Type mismatch: cannot convert from String to char   MoultonAlainaProject1.java  /TEST/src   line 101    Java Problem
    Type mismatch: cannot convert from String to char   MoultonAlainaProject1.java  /TEST/src   line 95 Java Problem
    Type mismatch: cannot convert from String to char   MoultonAlainaProject1.java  /TEST/src   line 89 Java Problem
    integer cannot be resolved  MoultonAlainaProject1.java  /TEST/src   line 83 Java Problem
    The method printIn(String) is undefined for the type PrintStream    MoultonAlainaProject1.java  /TEST/src   line 69 Java Problem
    integer cannot be resolved  MoultonAlainaProject1.java  /TEST/src   line 33 Java Problem
    JOption cannot be resolved  MoultonAlainaProject1.java  /TEST/src   line 30 Java Problem
    Syntax error, insert "}" to complete MethodBody MoultonAlainaProject1.java  /TEST/src   line 124    Java Problem
    Syntax error on token(s), misplaced construct(s)    MoultonAlainaProject1.java  /TEST/src   line 122    Java Problem
    exit cannot be resolved or is not a field   MoultonAlainaProject1.java  /TEST/src   line 122    Java Problem
    Syntax error on token(s), misplaced construct(s)    MoultonAlainaProject1.java  /TEST/src   line 120    Java Problem
    Type mismatch: cannot convert from String to char   MoultonAlainaProject1.java  /TEST/src   line 113    Java Problem
    Syntax error, insert "}" to complete ClassBody  MoultonAlainaProject1.java  /TEST/src   line 9  Java Problem
    Scanner cannot be resolved to a type    MoultonAlainaProject1.java  /TEST/src   line 23 Java Problem
    string cannot be resolved to a type MoultonAlainaProject1.java  /TEST/src   line 12 Java Problem
    integer cannot be resolved  MoultonAlainaProject1.java  /TEST/src   line 28 Java Problem
    Scanner cannot be resolved to a type    MoultonAlainaProject1.java  /TEST/src   line 23 Java Problem