How to override the ToString method of ArrayList of object?

Question

class Person {
  public String firstname;
  public String lastname;
}

Person p1 = new Person("Jim","Green");
Person p2 = new Person("Tony","White");

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

people.add(p1);
people.add(p2);

System.out.println(people.toString());

I'd like the output to be [Jim,Tony], what is the simplest way to override the ToString method if such a method exists at all?

Answer 1

You actually need to override toString() in your Person class, which will return the firstname, because, ArrayList automatically invokes the toString of the enclosing types to print string representation of elements.

@Override
public String toString() {
    return this.firstname;
}

So, add the above method to your Person class, and probably you will get what you want.

P.S.: - On a side note, you don't need to do people.toString(). Just do System.out.println(people), it will automatically invoke the toString() method for ArrayList.