What do the angle bracketed symbols at the end of a class name mean?

Question

For example look at this:

ArrayList<String> arrayList = new ArrayList<String>();

Could I use the <>s with a custom class? How do I use them?

you can use like this `ArrayList s= new ArrayList();` and add object of any class you want — Farnabaz, Mar 31 '13 at 09:13

score 3 · Answer 1 · answered Mar 31 '13 at 09:16

You can put any class in the <> as long as it fulfills the generic class's constraints:

ArrayList<MyClass> arrayList = new ArrayList<MyClass>();

You can define your own class to use the <> simply:

class MyGenericClass<E> {
    E e;
    MyGenericClass(E e) { this.e = e; }

    E getE() { return e; }
    void setE(E e) { this.e = e; }
}

Now you can make your own:

MyGenericClass<String> stuff = new MyGenericClass<String>("Foo");
System.out.println(stuff.getE());

score 2 · Answer 2 · answered Mar 31 '13 at 09:15

2

The tutorial Generics gives you all the information needed. The section Generic types shows how to declare and implement custom classes.

class MyClass<T> {
    ...
}

answered Mar 31 '13 at 09:15

Howard

2 Answers2