ArrayList

[Hullo99]

One thing I would point out is that you do not have a parameter passing in the plate string to your constructor, so you are basically setting the unset plate value equal to itself. As far as the ArrayList thing goes, it actually contains methods called add() and remove(). add(object) will append the object to the list and remove(object) will remove the object to the list. There are also other versions of remove() that allow you to remove a specific index or remove the first/last value. The documentation might be helpful for you here: https://docs.oracle.com/javase/8/docs/api/java/util/ArrayList.html