Android : Inconvertable types Cannot Cast ArrayList

Line with error:

persons = (PersonList) intent.getParcelableArrayListExtra(EXTRA_PERSON_LIST);

How PersonList is declared:

public class PersonList extends ArrayList<Person> {

How Person is declared:

public class Person extends CommonObject implements Parcelable {

Since PersonList extends ArrayList (Person) and Person implements Parcelable not sure why this doesn't work.