Inner classes are used primarily to implement helper classes. If you plan on handling user-interface events, you'll need to know about using inner classes because the event-handling mechanism makes extensive use of them.
There are two additional types of inner classes. You can declare an inner class within the body of a method. Such a class is known as a local inner class. You can also declare an inner class within the body of a method without naming it. These classes are known as anonymous inner classes.
