我有两个代码段。我特别遇到的问题是关于学生驱动程序中的dropCourse方法。我的代码中的所有内容似乎都可以正常运行，除非当我放弃某门课程时，它并没有减少课程学分。例如，如果我放下一个名为“ Computer101”的课程，该课程有4个学分，则它将从时间表中删除“ Computer101”，但是当我选择选项5来打印总学分时，则不会删除“ 4”学分。因此，如果我们有完整的时间表：
位置101的计算机101可获得4个学分
排名1的Physics105拥有4个学分
第2位的Art101，价值4个学分
排名3的Chem101价值4个学分
我决定从时间表中删除Computer101，所有其他类将按照预期的方式在数组中向上移动，在打印时间表时该类将不再显示，并且在搜索时将找不到，但是值得的信用额仍然存在。我觉得解决方案就在我眼前，但是我非常疲倦，看不到它。我非常感谢您的帮助，希望我能清楚自己的要求。
在这里可以找到我的dropCourse方法：
public class Student
{
//Instance Data
String studentName;
String studentID;
String streetAddress;
String city;
String state;
String zipCode;
String major;
final int MAX_CREDITS = 18;
int courseNumber = 0; //start out with no courses
int totalCredits;
final int SIZE = 6;
String [ ] schedule = new String [SIZE];
//Create Constructor:
//Initializes the student data at instantiation time.
//-------------------------------------------------------
// Sets up the student's information.
//-------------------------------------------------------
public Student (String name, String id, String address, String cityName, String stateName, String zip, String area )
{
studentName = name;
studentID = id;
streetAddress = address;
city = cityName;
state = stateName;
zipCode = zip;
major = area;
}//end Student Constructor
//Method to Return student information as string:
//-------------------------------------------------------
// Returns the student information as a formatted string.
//-------------------------------------------------------
public String toString()
{
String studentInfo;
studentInfo = "Name:\t\t\t" + studentName + "\n" + "ID:\t\t\t" + studentID + "\n" + "Address:\t\t" + streetAddress
+ "\n" + "City:\t\t\t" + city + "\n" + "State:\t\t\t" + state + "\n" + "Zip Code:\t\t" + zipCode
+ "\n" + "Major:\t\t\t" + major + "\n";
return studentInfo;
}// end toString
//Method to determine if maximum allowed credits have been exceeded
//-------------------------------------------------------
// Returns true if total credits does not exceed 18.
//-------------------------------------------------------
private boolean checkCredits(int numCredits)
{
if (numCredits + totalCredits <= MAX_CREDITS) //make sure max credits not exceeded
{
return true; //return a true if still less than 18 credits
}
else
{
return false; //return a false if 18 credit limit is exceeded
}//end numCredits
}//checkCredits
//Method to add a course to the student’s schedule
//-------------------------------------------------------
// Adds a course to the array if total credits does not exceed 18.
//-------------------------------------------------------
public void addCourse(String course, int numCredits)
{
if (courseNumber < SIZE ) //make sure array is not full.
{
if (checkCredits(numCredits) == true) //if we’re under 18 credits
{
//add course
schedule [courseNumber] = course + ":\t\t" + numCredits + "\tCredits\n";
//increment number of credits
totalCredits = totalCredits + numCredits;
//increment number of courses
courseNumber = courseNumber + 1;
System.out.println("The course has been added!");
}
else //oops – can’t do more than 18 credits
{
System.out.println("You have exceeded the maximum allowed credits.");
}//end checkCredits
}
else //oops – can’t do more than 6 courses
{
System.out.println("You have exceeded 6 courses.");
}//end courseNumber
}//addCourse
public void displaySchedule( )
{
for (int index = 0; index < courseNumber; index++)
{
System.out.println("Course #" + (index + 1) + " " + schedule[index] + "\n");
}//end for
}//end display schedule
public int searchCourse(String courseName)
{
String course;
boolean flag = false;
int index = 0;
while(index < courseNumber && flag == false)
{
String extract = schedule[index].substring(0,6);
if (extract.contains(courseName) == true)
{
flag = true;
}
else
{
index++;
}
}
if (flag == false)
{
return -1;
}
else
{
return index++;
}
}
public void dropCourse(String courseName)
{
int found;
found = searchCourse(courseName);
int index = 0;
if (found == -1)
{
System.out.println("Course not in schedule");
}
else
{
if (found == 5)
{
courseNumber = courseNumber -1;
}
else
{
for (index = found; index < courseNumber; index ++)
{
schedule[index] = schedule[index + 1];
}
courseNumber = courseNumber -1;
System.out.println("The course has been dropped!");
}
}
}
public int totalCredits()
{
System.out.println("The total credits are " + totalCredits);
return totalCredits;
}
}//end class Student
这是与上述代码一起使用的菜单在这里：
//This is a Driver program to test the external Class named Student
import java.util.Scanner;
public class TheMenu //BEGIN Class Definition
{
//**************** Main Method*************************
static Scanner scan = new Scanner(System.in);
public static void main (String[] args)
{
//Data Definitions:
//Instance Data
String name;
String id;
String street;
String city;
String state;
String zip;
String major;
String courseName;
int courseCredits;
int menu = 0;
//Initialize first Student
name = "Florence Welch";//look her up
id = "7777";
street = "777 Heaven Street";
city = "Witchville";
state = "NY";
zip = "12345";
major = "Arts";
//instantiate the Student object
Student student1 = new Student(name, id, street, city, state, zip, major);
while (menu < 6)//begin while for menu options
{
System.out.println("1. Add a course ");
System.out.println("2. Search for a course");
System.out.println("3. Drop a course");
System.out.println("4. Print out a student's schedule");
System.out.println("5. Print out total credits");
System.out.println("6. Exit");
System.out.println("Enter an option: ");
menu = scan.nextInt();
if (menu == 1)//option to add course
{
System.out.println("Please enter the name of the course: ");
courseName = scan.next();
System.out.println("How many credits is the course? ");
courseCredits = scan.nextInt();
student1.addCourse(courseName, courseCredits);//uses method to store course information in array
}
else if (menu == 2)//option to search for course
{
int x;
System.out.println("Please enter the name of the course: ");
courseName = scan.next();
student1.searchCourse(courseName);
x = student1.searchCourse(courseName);
if (x == -1)//course is not found if value returns -1
{
System.out.println("Course not found");
}
else
{
System.out.println("Course found in position " + student1.searchCourse(courseName));//shows user the position of course
}
}
else if (menu == 3)//will drop course from users schedule
{
System.out.println("Please enter the course you wish to drop: ");
courseName = scan.next();
student1.dropCourse(courseName);
}
else if (menu == 4)//displays the users schedule
{
System.out.println(name + "'s Schedule:\n\n");
student1.displaySchedule();
}
else if (menu == 5)//will display users credits for semester
{
student1.totalCredits();
}
else
{
System.out.println("Enjoy your semester!");//option 6 will exit program
}
}
}
}