ArrayList from a method with a counter++ variable - arraylist

Question

I need to call the method student, creating a student with a student ID that starts at 1 and increases with each new student, then take that new student and add it to an ArrayList. However, my list just gets the ID number that was last called and gives it to all members of the list. If I put in "James" with GPA 3.4 and "Jack" with GPA 2.9, it will return both students with the same student id of 2. I need help getting it to give James an ID of 1, Jack an ID of 2, and so on. The first block is from my main method and the second at the end is from the class itself.
ArrayList list1 = new ArrayList();
int option = -1;
String name;
double gpa;
Scanner studentInput = new Scanner(System.in);
Scanner gpaInput = new Scanner(System.in);
Scanner optionInput = new Scanner(System.in);
while (option != 0) {
System.out.println("Please choose an option:");
System.out.println("0: quit");
System.out.println("1: Add a student to your list");
System.out.println("2: Display your student list");
option = optionInput.nextInt();
switch (option) {
case 0:
System.out.println("Have a good Day!");
break;
case 1:
System.out.println("Please enter the students name.");
name = studentInput.next();
System.out.println("Please enter the students GPA.");
gpa = gpaInput.nextDouble();
Student studentA = new Student(name, gpa);
list1.add(studentA);
break;
case 2:
System.out.println("Here is your list so far.");
for (int i = 0; i < list1.size(); i++) {
System.out.println(list1.get(i));
}
}
}
public class Student implements Comparable {
private static int studentID = 0;
private String name;
private double gpa;
public Student( String name, double gpa) {
studentID++;
this.name = name;
this.gpa = gpa;
}
public int getStudentID() {
return studentID;
}
public void setStudentID(int studentID) {
this.studentID = studentID;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getGpa() {
return gpa;
}
public void setGpa(double gpa) {
this.gpa = gpa;
}
}

Answer 1

The studentID field in your class is shared between all instances of Student, so if its value changes, getStudentID will return the new value for all instances. To fix this, add another non-static field for the student ID, then store the value of the static field into the field you just added in the constructor:
public class Student implements Comparable {
private static int globalStudentID;
private int studentID;
private String name;
private double gpa;
public Student( String name, double gpa) {
globalStudentID++;
this.studentID = globalStudentID;
this.name = name;
this.gpa = gpa;
}
public int getStudentID() {
return studentID;
}
public void setStudentID(int studentID) {
this.studentID = studentID;
}
// ...
}