Java initializer block trick

Here's a neat trick Kevlin Henney found in some code Michael Feathers posted at http://pastie.org/534364 Instead of doing this:

ArrayList<Integer> values = new ArrayList<Integer>();
values.add(1);
values.add(2);
values.add(3);

You can do this:

ArrayList<Integer> values = new ArrayList<Integer>() {{
    add(1);
    add(2);
    add(3);
}};