下面是代码：
驱动：
package myschool;
import java.util.ArrayList;
import java.util.Scanner;
public class MySchool {
public static void main(String[] args) {
ArrayList<Student> listStudent = new ArrayList<>();
ArrayList<Course> listCourse = new ArrayList<>();
Student s = new Student();
Course c = new Course();
boolean continueLoop = true;
Scanner userInput = new Scanner(System.in);
Scanner courseAddInput = new Scanner(System.in);
int option;
do{
try {
System.out.println(" What would you like to do?");
System.out.println(" 1) Add a student");
System.out.println(" 2) View students");
System.out.println(" 3) Remove a student");
System.out.println(" 4) Exit");
System.out.print("--> ");
option = userInput.nextInt();
switch( option ){
case 1:
Scanner inputs = new Scanner(System.in);
String fName, lName;
int sID;
double sGPA;
System.out.print(" First Name:");
fName = inputs.nextLine();
s.setStudentFirstName( fName );
System.out.print(" Last Name:");
lName = inputs.nextLine();
s.setStudentLastName( lName );
System.out.print(" ID Number:");
sID = inputs.nextInt();
s.setStudentID( sID );
System.out.print(" GPA:");
sGPA = inputs.nextDouble();
s.setStudentGPA( sGPA );
String cName, instructor, cBeginTime, cEndTime, cDay;
int i = 0, cID, cCred;
boolean continueAdd = true;
Scanner input = new Scanner(System.in);
Scanner input2 = new Scanner(System.in);
String addCourse;
do{
System.out.println("Would you like to add a course? Y/N");
addCourse = input2.nextLine();
if( "N".equals(addCourse)|| "n".equals(addCourse))
continueAdd = false;
if(continueAdd){
System.out.print(" CourseName:");
cName = input.nextLine();
c.setCourseName( cName );
System.out.print(" Instructor:");
instructor = input.nextLine();
c.setCourseInstructor( instructor );
System.out.print(" CourseID:");
cID = input.nextInt();
c.setCourseID( cID );
System.out.print(" CourseCredit:");
cCred = input.nextInt();
c.setCourseCred( cCred );
/*System.out.print(" StartTime:");
cBeginTime = input.nextLine();
c.setCourseBeginTime(cBeginTime);
System.out.print(" EndTime:");
cEndTime = input2.nextLine();
c.setCourseEndTime(cEndTime);*/
listCourse.add( new Course( c.getCourseName(), c.getCourseInstructor(), c.getCourseCred(), c.getCourseBeginTime(), c.getCourseEndTime(), c.getCourseID() ));
}
}while( continueAdd );
listStudent.add( new Student( s.getStudentFirstName(),s.getStudentLastName(), s.getStudentID(), s.getStudentGPA(), listCourse));
break;
case 2:
if(!listStudent.isEmpty()){
for(Student l:listStudent) {
System.out.println(l);
for(Course n:listCourse) {
System.out.println(n);
}
System.out.println();
}
}else
System.out.println("There are no students to view\n");
break;
case 3:
Scanner removeChoice = new Scanner(System.in);
try {
if(!listStudent.isEmpty()){
int j = 0;
System.out.println("Which student do you want to remove?");
for(Student l:listStudent) {
System.out.print(j+1 + ")");
System.out.println(l);
j++;
}
int remove = removeChoice.nextInt();
listStudent.remove( remove - 1 );
System.out.println("Student has been removed\n");
}else
System.out.println("There are no students to remove\n");
} catch (Exception e) {
System.out.println("There are no students to remove\n");
}
break;
case 4:
continueLoop = false;
break;
}
} catch (Exception e) {
System.out.println("That is not a valid option!!!");
continueLoop = false;
}
}while( continueLoop );
}
}
///////////Student Class///////////
package myschool;
import java.util.ArrayList;
public class Student {
String studentFirstName, studentLastName;
int studentID;
double studentGPA;
ArrayList<Course> listCourse = new ArrayList<>();
Student(){}
public Student(String studentFirstName, String studentLastName, int studentID, double studentGPA, ArrayList courseList) {
this.studentFirstName = studentFirstName;
this.studentLastName = studentLastName;
this.studentID = studentID;
this.studentGPA = studentGPA;
this.listCourse = courseList;
}
public void setListCourse(ArrayList<Course> listCourse) {
this.listCourse = listCourse;
}
public ArrayList<Course> getListCourse() {
return listCourse;
}
public void setStudentFirstName(String studentFirstName) {
this.studentFirstName = studentFirstName;
}
public String getStudentFirstName() {
return studentFirstName;
}
public void setStudentLastName(String studentLastName) {
this.studentLastName = studentLastName;
}
public String getStudentLastName() {
return studentLastName;
}
public void setStudentID(int studentID) {
this.studentID = studentID;
}
public int getStudentID() {
return studentID;
}
public void setStudentGPA(double studentGPA) {
this.studentGPA = studentGPA;
}
public double getStudentGPA() {
return studentGPA;
}
@Override
public String toString() {
return ("FirstName:" + this.getStudentFirstName() +
" LastName:" + this.getStudentLastName() +
" ID:" + this.getStudentID() +
" GPA:" + this.getStudentGPA());
}
}
///////////Course Class//////////////
package myschool;
public class Course {
private String courseName, courseInstructor, courseBeginTime, courseEndTime;
int courseID, courseCred;
Course(){}
public Course(String courseName, String courseInstructor, int courseCred, String courseBeginTime, String courseEndTime, int courseID) {
this.courseName = courseName;
this.courseInstructor = courseInstructor;
this.courseCred = courseCred;
this.courseBeginTime = courseBeginTime;
this.courseEndTime = courseEndTime;
this.courseID = courseID;
}
public void setCourseName(String courseName) {
this.courseName = courseName;
}
public String getCourseName() {
return courseName;
}
public void setCourseInstructor(String courseInstructor) {
this.courseInstructor = courseInstructor;
}
public String getCourseInstructor() {
return courseInstructor;
}
public void setCourseCred( int courseCred) {
this.courseCred = courseCred;
}
public int getCourseCred() {
return courseCred;
}
public String getCourseBeginTime() {
return courseBeginTime;
}
public void setCourseBeginTime(String courseBeginTime) {
this.courseBeginTime = courseBeginTime;
}
public void setCourseEndTime(String courseEndTime) {
this.courseEndTime = courseEndTime;
}
public String getCourseEndTime() {
return courseEndTime;
}
public void setCourseID(int courseID) {
this.courseID = courseID;
}
public int getCourseID() {
return courseID;
}
@Override
public String toString() {
return( "Course Name:" + this.getCourseName()
+ " Course ID:" + this.getCourseBeginTime()
+ " Instructor:" + this.getCourseInstructor()
+ " Credit:" + this.getCourseCred()
+ " Begin Time:" + this.getCourseBeginTime()
+ " End Time:" + this.getCourseEndTime());
}
}
这是在运行时发生的事情
What would you like to do?
1) Add a student
2) View students
3) Remove a student
4) Exit
--> 1
First Name:Mike
Last Name:Smith
ID Number:2345
GPA:4
Would you like to add a course? Y/N
y
CourseName:MAth
Instructor:get
CourseID:123
CourseCredit:3
Would you like to add a course? Y/N
n
What would you like to do?
1) Add a student
2) View students
3) Remove a student
4) Exit
--> 1
First Name:Sarah
Last Name:Smoith
ID Number:42342
GPA:3
Would you like to add a course? Y/N
y
CourseName:Science
Instructor:tra;l
CourseID:345
CourseCredit:4
Would you like to add a course? Y/N
n
What would you like to do?
1) Add a student
2) View students
3) Remove a student
4) Exit
--> 2
FirstName:Mike LastName:Smith ID:2345 GPA:4.0
Course Name:MAth Course ID:null Instructor:get Credit:3 Begin Time:null End Time:null
Course Name:Science Course ID:null Instructor:tra;l Credit:4 Begin Time:null End Time:null
FirstName:Sarah LastName:Smoith ID:42342 GPA:3.0
Course Name:MAth Course ID:null Instructor:get Credit:3 Begin Time:null End Time:null
Course Name:Science Course ID:null Instructor:tra;l Credit:4 Begin Time:null End Time:null
答案 0 :(得分：1)
你的toString方法有问题，请查看评论：
public String toString() {
return( "Course Name:" + this.getCourseName()
+ " Course ID:" + this.getCourseBeginTime() // getCourseID should be used here
+ " Instructor:" + this.getCourseInstructor()
+ " Credit:" + this.getCourseCred()
+ " Begin Time:" + this.getCourseBeginTime()
+ " End Time:" + this.getCourseEndTime());
}
所以适当更新所有getter调用：
答案 1 :(得分：1)
请查看Course类的toString（）方法。
Course ID:" + this.getCourseBeginTime() // should be getCourseId