Why so many inner classes in Android?

Question

I am a new fish in Android development. While reading books and Android source code I found out that there so many inner classes in the Android application. Why does Android need so many inner classes?

I am confused by these inner classes.

Answer 1

They are often the most efficient way of implementing a design.

An inner class can access the private members of the class which contains it, so using an inner class allows a split of functionality between classes without the need to add accessor methods for private variables.

Answer 2

Inner classes are not just in Android. I guess you need to understand why they are good in some cases.

Check this article about Inner classes: Inner classes: So what are inner classes good for anyway?.