Question

public ArrayList<Person> people;

Is this how you would instantiate the people variable as a new empty ArrayList of Person objects?

ArrayList<Person> people = new ArrayList<Person>();

And is this how you would add newMember to the end of the list?

public void addItem(Person newMember){
            people.add(newMember);

    }

Answer 1

No

class Foo {
  public ArrayList<Person> people;

  Foo() {
    //this:
    ArrayList<Person> people = new ArrayList<Person>();
    //creates a new variable also called people!

    System.out.println(this.people);// prints "null"!
    System.out.println(people);//prints "bladiebla"
  }
  Foo() {
    people = new ArrayList<Person>();//this DOES work
  }
}

---

What it could(or should) look like:
private, List instead of ArrayList and this. so you never make that mistake again:

public class Foo {
  private List<Person> people;

  public Foo() {
    this.people = new ArrayList<Person>();
  }
  public void addItem(Person newMember) {
    people.add(newMember);
  }
}