错误表达式的非法开始
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【中文标题】错误表达式的非法开始【英文标题】：error illegal start of expression 【发布时间】：2014-03-09 20:58:08 【问题描述】：我不断得到：
表达式的非法开始，';" 预期 System.exit(0)，并达到 解析时文件结束
这是它应该做什么和代码的描述。
要解决的问题： 我应该在课外学习多少？
问题： 你的同学需要帮助。这是他们上大学的第一年，他们需要确定需要学习多少小时才能获得好成绩。
Study Hrs Per Week Per Credit Grade
5: A,
4: B,
3: C,
2: D,
0: F,
项目规格：
-
用户可以输入他们计划每人学习的小时数
周或他们想要的等级基于他们的学分
进入。 （注意：您的程序必须为用户提供两个选项。）
程序显示用户名、学分数、总数
学习小时数，以及他们应该期望获得的成绩。
您可以使用介绍中介绍的任何编程技术
编程逻辑课程来完成这个项目。那将
但是，要求您在课本中提前阅读
关于如何在 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);
我已经检查了很多次牙套，但我可能在某个地方漏掉了一些东西
【问题讨论】：
string wantedGrade, desiredGrade, name, input; 应该是 String wantedGrade, desiredGrade, name, input; （除非您创建了一个 string 类，这将是一个非常糟糕的名称）
字符串在 Java 中大写。
【参考方案1】：
您有大约 20 个编译时错误。 我看到缺少导入、用小写字母书写的字符串、未闭合的括号， 未闭合的花括号，将字符串值分配给 char 变量等。 请参见下文并修复它们。
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
【讨论】：
【参考方案2】： JOptionPane.showMessageDialog(null, name+ ", you are taking " +creditHrs+ "credit hours, you should study " +studyHrs+ " hours a week to receive " +finalGrade+ " in your classes."
showMessageDialog() 方法不完整。您缺少右括号和分号。
【讨论】：
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