What is this type of initialization called and why is it used? [duplicate]

Answer 1

This is used to override the initial

Animal.makeNoise()

method with a custom one for just this instance.

Answer 2

That is an anonymous class. For details about anonymous classes and why they are useful, see this tutorial on anonymous classes.

Answer 3

Its called an anonymous class and used to define the class and any overridden methods at the same time.