| Chapter 4 introduced you to classes and objects. In this chapter, you will learn about inheritance, another fundamental concept of object-oriented programming. The idea behind inheritance is that you can create new classes that are built upon existing classes. When you inherit from an existing class, you reuse (or inherit) methods and fields, and you add new methods and fields to adapt your new class to new situations. This technique is essential in Java programming. As with the previous chapter, if you are coming from a procedure-oriented language like C, Visual Basic, or COBOL, you will want to read this chapter carefully. For experienced C++ programmers or those coming from another object-oriented language like Smalltalk, this chapter will seem largely familiar, but there are many differences between how inheritance is implemented in Java and how it is done in C++ or in other object-oriented languages. The latter part of this chapter covers reflection, the ability to find out more about classes and their properties in a running program. Reflection is a powerful feature, but it is undeniably complex. Since reflection is of greater interest to tools builders than to application programmers, you can probably glance over that part of the chapter upon first reading and come back to it later. |
