ArrayList.remove() is not removing an object

Question

I know this is a messy implementation, but I basically have this code (I wrote all of it), and I need to be able to remove a student or instructor from the list when using t

Answer 1

You must correctly override the equals() method for both Student and Instructor classes.

When overriding equals, it is good to override hashCode() as well. new Student(name, id, GPA);

For example, something like this:

public boolean equals(Object o) {
  if (!(o instanceof Student)) {
    return false;
  }
  Student other = (Student) o;
  return name.equals(other.name) && id.equals(other.id) && GPA == other.GPA;
}

public int hashCode() {
  return name.hashCode();
}

This way, you give a chance to the ArrayList figure out which object correspond to the one you passed as a parameter when deleting. If you don't override the above methods, it will use the default implementations in Object, which compare memory addresses which are definitely different as you remove a new Student object.

You can read even more information about the 2 methods in the javadocs for Object.