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我需要幫助從陣列列表中刪除特定對象。我爲每個對象創建具有唯一ID和等級的對象。我嘗試使用此唯一ID從ArrayList中刪除對象，但無法弄清楚爲什麼我的代碼無法工作。我有我的主要Driver類，一個超類和一個子類。從陣列列表中刪除特定對象
子類是對象信息從超類傳遞和擴展的地方。我認爲，由於子類是擴展的，所以可以從那裏定義。
正在發生的問題是超類的第49行。 Eclipse說getStudentID沒有在類中定義。
我試圖修改我的教師提供的代碼，以便找到arraylist中的對象具有的唯一ID。我相信我所做的一切都正確，但「locationPerson」方法似乎沒有在子類中看到getStudentID（）方法。
這是代碼。任何幫助，將不勝感激！
子類
public class StudentEnrollee extends ClassSection{
private int grade;
private String studentID;
StudentEnrollee() {
setStudentID("000-000");
setGrade(0);
}
StudentEnrollee(String ID, int theGrade) {
setStudentID(ID);
setGrade(0);
}
//STUDENT ID
public String getStudentID() {
return studentID;
}
public void setStudentID(String theStudentID) {
this.studentID = theStudentID;
}
//STUDENT GRADE
public int getGrade() {
return grade;
}
public void setGrade(int studentGrade) {
this.grade = studentGrade;
}
public String toString() {
return("Student ID : " + studentID + "\n" +
"Student Grade: " + grade);
}
}
超類
import java.util.ArrayList;
import java.util.List;
public class ClassSection {
private int crn, courseNumber, capacity, enrollment, ID, student;
private String departmentCode, courseMode, meetingDay, meetingTime;
//CONSTRUCTOR
ClassSection() {
setCrn(0);
setDepartmentCode("");
setCourseNumber(0);
setCourseMode("");
setMeetingDay("");
setMeetingTime("");
setCapacity(0);
setEnrollment(0);
setID(0);
}
ClassSection(int crn, String departmentCode, int courseNumber, String courseMode, String meetingDay, String meetingTime, int capacity, int enrollment, int ID) {
setCrn(crn);
setDepartmentCode(departmentCode);
setCourseNumber(courseNumber);
setCourseMode(courseMode);
setMeetingDay(meetingDay);
setMeetingTime(meetingTime);
setCapacity(capacity);
setEnrollment(enrollment);
setID(ID);
}
//STUDENT ENROLL ARRAY
List <StudentEnrollee> studentList = new ArrayList <StudentEnrollee>();
public int getStudent() {
return student;
}
public void addStudent(StudentEnrollee studentObject) {
studentList.add(studentObject);
}
//LOCATING PERSON
public ClassSection locatePerson(String getStudentID) {
for (ClassSection personObject: studentList) {
if (personObject.getStudentID().equals(getStudentID)) {
return personObject;
}
}
return null;
}
//Delete person
public void deletePerson(String studentID) {
ClassSection personObject = locatePerson(studentID); // we'll use our locatePerson method find the index of a Person with a given socSecNum.
if (personObject != null) studentList.remove(personObject); // if element i contains the target SSN, remove it.
}
//DISPLAY LIST OF ENROLLEE
public void displayListV1() {
for (int i = 0; i < studentList.size(); i++) // the old way
{
System.out.println(studentList.get(i) + "\n");
}
}
//CRN
public int getCrn() {
return crn;
}
void setCrn(int classCrn) {
this.crn = classCrn;
}
//DEPARTMENT CODE
public String getDepartmentCode() {
return departmentCode;
}
void setDepartmentCode(String classDepartmentCode) {
this.departmentCode = classDepartmentCode;
}
//COURSE NUMBER
public int getCourseNumber() {
return courseNumber;
}
void setCourseNumber(int classCourseNumber) {
this.courseNumber = classCourseNumber;
}
//COURSE LOCATION
public String getCourseMode() {
return courseMode;
}
public void setCourseMode(String classCourseMode) {
this.courseMode = classCourseMode;
}
//MEETING DAY
public String getMeetingDay() {
return meetingDay;
}
public void setMeetingDay(String classMeetingDay) {
this.meetingDay = classMeetingDay;
}
//MEETING TIMES
public String getMeetingTime() {
return meetingTime;
}
public void setMeetingTime(String classMeetingTime) {
this.meetingTime = classMeetingTime;
}
//CAPACITY
public int getCapacity() {
return capacity;
}
public void setCapacity(int classCapacity) {
this.capacity = classCapacity;
}
//ENROLLMENT
public int getEnrollment() {
return enrollment;
}
public void setEnrollment(int classEnrollment) {
this.enrollment = classEnrollment;
}
//INSTRUCTOR ID
public int getID() {
return ID;
}
public void setID(int instructorID) {
this.ID = instructorID;
}
//TO STRING METHOD
public String toString() {
return ("CRN :" + crn + "\n" +
"Department :" + departmentCode + "\n" +
"Course Number :" + courseNumber + "\n" +
"Instructional mode :" + courseMode + "\n" +
"Meeting days :" + meetingDay + "\n" +
"Meeting times :" + meetingTime + "\n" +
"Capacity :" + capacity + "\n" +
"Enrollment :" + enrollment + "\n" +
"Instructor’s ID :" + ID + "\n");
}
}
驅動
public class ClassDriver {
public static void main(String[] args) {
ClassSection firstInstance = new ClassSection(20008, "CHM", 000, "Online", "N/A", "N/A", 30, 21, 231);
ClassSection secondInstance = new ClassSection();
ClassSection addToList = new ClassSection();
StudentEnrollee studentObj1 = new StudentEnrollee();
StudentEnrollee studentObj2 = new StudentEnrollee();
StudentEnrollee studentObj3 = new StudentEnrollee();
studentObj1.setGrade(5);
studentObj1.setID(230);
studentObj2.setGrade(76);
studentObj2.setID(45);
studentObj3.setGrade(2);
studentObj3.setID(34);
addToList.addStudent(studentObj1);
addToList.addStudent(studentObj2);
addToList.addStudent(studentObj3);
addToList.deletePerson("45");
addToList.displayListV1();
System.out.println(firstInstance.toString());
System.out.println(secondInstance.toString());
}
}
這是一個很大的代碼，您已發佈。如果僅發佈代碼的相關部分，則可能更有可能獲得幫助。此外，如果您明確指出哪一行是*「超類的第49行」，則會有所幫助，因爲您的帖子不包含行號。 – EJK
您可能會考慮使用HashSet，其中String是您的唯一ID，而對象實例是YourObjectType –
Constantin