Specify the type for ArrayList

Question

In Java, and Android, I end up using ArrayList<String> for the supplying list as I find them easier to use than the standard String[]. My real questions though are this:

What is the <String> portion of the ArrayList<String> called?
How can I create classes and use the <> [modifier]? (I don't know what it's actually called, so for now it's modifier).

Thanks!

Answer 1

Here, you wil maybe see clearer:

ArrayList<TypeOfYourClass>

You can create a Person class and pass it to an ArrayList as this snippet is showing:

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

Answer 2

Supose you want an ArrayList to be filled only with Strings. If you write:

ArrayList<String> list = new ArrayList<String>();
    list.add("A");
    list.add("B");
    list.add("C");

You can be sure than if somebody tries to fill the arrayList with an int it will be detected in complile time.

So, generics are used in situations where you want enforce restrictions like this.