It uses simple Java program examples to demonstrate application code constructs and programming concepts. These examples reveal the elements of object-oriented programming, I.e., classes, subclasses, instances, inheritance, encapsulation and polymorphism. The subclass object can be used as is, or enhanced with additional properties. An instance is one of a set of class object. Inheritance is the process of transmitting characteristics from a parent to a child, should a change be made in the parent class object.
Encapsulation places a protective shell around the program code.
Finally, polymorphism is the ability of an object to send the same generic message to many other objects, where each object implements that message based on other pre-determined information held by that object. The objective of this book is to teach both how to use and to develop with the Java Language. The reader is brought up from the very basics of the language, its constructs and features, what is object-oriented programming, how to implement OOP in development, creating applets and putting all the pieces together. One instance is the example of the four function calculator. We have all at sometime or another used a variation of the four function calculator to do some needed calculation.