我是大学新生，我在编程作业上遇到了麻烦。我从讲师那里得到的作业是为我编写一个Java语言程序来获取学生的信息，并允许学生选择该学生要学习的科目，并输入分数和学分，然后是一个公式来计算年级和学科成绩点。在该程序的最后，该程序将能够输出学生信息（姓名，ID等）和所有已输入学科的总学科成绩点，所有学科的总学时数以及累计平均绩点（CGPA）。
但是，我这里有三个问题
为了读取用户要键入的主题数，我设置的循环出现了问题。
当我尝试打印“ Grade =” + subjectGrade）时；我的编译器说它还没有初始化。同样，GradePoint和subjectCreditHour也是如此。
而且我不知道如何获得该程序来计算总科目成绩，总学时和CGPA。因为取决于用户想要多少个主题，我无法弄清楚如何使程序接受用户的输入并将它们汇总在一起
我的代码是这样的：
package javaquiz1;
import java.util.Scanner;
/**
*
* @author jerem_000
*/
public class JavaQuiz1 {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
Scanner input = new Scanner (System.in);
String name;
int ID;
int tel;
String email;
int subjects;
String subjectName;
int subjectCreditHour;
int subjectMark;
String subjectGrade;
double GradePoint;
double subjectGradePoint;
double CGPA;
double totalSubjectGP;
int totalCreditHour;
System.out.print("Please input student's name : ");
name = input.nextLine();
System.out.print("Please input student's ID : ");
ID = input.nextInt();
System.out.print("Please input student's telephone number : ");
tel = input.nextInt();
System.out.print("Please input student's email : ");
email = input.next();
System.out.print("Please input number of subjects : ");
subjects = input.nextInt();
for (int i = 1; i >= subjects ; i++) { //I'm having an issue with this loop
System.out.println("Subject " + i + " : Please input the following"); //I placed the variable i there in order to make the program print something like "Subject 1 , Subject 2, Subject 3 etc". Depending on the user's number of subjects input
System.out.print("Subject name : ");
subjectName = input.next();
System.out.print("Credit Hour : ");
subjectCreditHour = input.nextInt();
System.out.print("Mark : ");
subjectMark = input.nextInt();
if ( subjectMark >= 80 ) {
subjectGrade = "A";
GradePoint = 4.0;
} else if (subjectMark < 80) {
subjectGrade = "B+";
GradePoint = 3.5;
} else if (subjectMark < 70) {
subjectGrade = "B";
GradePoint = 3.0;
} else if (subjectMark < 65) {
subjectGrade = "C+";
GradePoint = 2.5;
} else if (subjectMark < 55) {
subjectGrade = "C";
GradePoint = 2.0;
} else if (subjectMark < 50) {
subjectGrade = "D";
GradePoint = 1.0;
} else {
subjectGrade = "F";
GradePoint = 0.0;
}
}
System.out.println("Grade = " + subjectGrade);
System.out.println("Subject Grade Point = " + (GradePoint * subjectCreditHour)); //I'm having a problem with the subjectGrade, GradePoint, and subjectCreditHour, it says variable might have not been initialized
System.out.println("Name : " + name);
System.out.println("ID : " + ID);
System.out.println("Tel : " + tel);
System.out.println("email : " + email);
System.out.print("Total subject Grade Points = " );
System.out.print("Total Credit Hours = " );
System.out.print("Cumulative Grade Point Average ="); //On this 3 system.out.prints, I can't seem to think of a way to read the Grade Point, Total Credit Hours, and CGPA, and add them all together
}
}
我也有一个示例程序输出示例：
Please input student's name : James Cook
Please input student's ID : 0106578
Please input student's tel : 010783938
Please input student's e-mail : [email protected]
Please input number of subjects : 3
Subject 1 : Please input the following
Subject name : Fundamentals of Programming
Credit Hour : 4
Mark : 78
Grade : B+
Subject Grade Point : 14.0
Subject 2 : Please input the following
Subject name : English
Credit Hour : 3
Mark : 85
Grade : A
Subject Grade Point : 12.0
Subject 3 : Please input the following
Subject name : Computer Fundamentals
Credit Hour : 3
Mark : 78
Grade : B+
Subject Grade Point : 10.5
Name : James Cook
ID : 0106578
tel : 010783938
e-mail : [email protected]
Total subject Grade Point = 36.5
Total Credit Hours = 10
CGPA = 3.65
计算学科成绩的公式是
subjectGradePoint = GradePoint * CreditHour
并且计算CGPA（累积平均成绩）的公式为
CGPA = totalSubjectGP / totalCreditHours
纠正，批评和建议将受到欢迎，以便将来进行改进。提前致谢！
最佳答案
1）我为了查看如何设置的循环而遇到了问题
用户想要键入的许多主题。
@Nishan已在评论中回答。只需将for (int i=1;i >= subjects; i++)替换为for (int i=1;i <= subjects; i++)。
2）当我尝试打印“ Grade =” + subjectGrade）时；我的编译器说
尚未初始化。同样，GradePoint和
subjectCreditHour。
已经回答。
3）而且我不知道如何获取程序来计算
总科目成绩，总学时和CGPA。因为
根据用户想要多少个学科，我不能
弄清楚如何使程序接受用户的输入和求和
他们在一起
由于您拥有所需的累加器，因此您已经处于正确的方法：
double subjectGradePoint = 0d;
double CGPA = 0d;
double totalSubjectGP = 0d;
int totalCreditHour = 0;
循环循环并嵌套
if-else块之后，您需要在每次迭代中更新subjectGradePoint，totalSubjectGP和totalCreditHour变量：subjectGradePoint = GradePoint * CreditHour;
totalSubjectGP += subjectGradePoint;
totalCreditHour += CreditHour;
最后，在循环之后计算
CGPA：CGPA = totalSubjectGP / totalCreditHour;