Chapter 9 Inheritance
As your programs grow in size, you will define more classes, many of which may have identical methods and fields, especially when they are related. This ends up making program maintenance very difficult and it violates the DRY principle. Sooner or later a mistake will be made due to the excessive maintenance required with repeated code. A much more maintainable approach is to define the shared parts of your program once, and share that single authoritative implementation with the rest of your program. One way to accomplish this is through the use of inheritance.
