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Bruce Eckel’s Thinking in Java Contents | Prev | Next and methods In all the instrument examples, the methods in the base class Instrument were always “dummy” methods. If these methods are ever called, you’ve done something wrong. That’s because the intent of Instrument is to create a common interface for all the classes derived […]

Bruce Eckel’s Thinking in Java Contents | Prev | Next As usual, constructors are different from other kinds of methods. This is also true when polymorphism is involved. Even though constructors are not polymorphic (although you can have a kind of “virtual constructor,” as you will see in Chapter 11), it’s important to understand the […]

Bruce Eckel’s Thinking in Java Contents | Prev | Next Let’s take a different look at the first example in this chapter. In the following program, the interface of the method play( ) is changed in the process of overriding it, which means that you haven’t overridden the method, but instead overloaded it. The compiler allows […]

Bruce Eckel’s Thinking in Java Contents | Prev | Next The difficulty with Music.java can be seen by running the program. The output is Wind.play( ). This is clearly the desired output, but it doesn’t seem to make sense that it would work that way. Look at the tune( ) method: public static void tune(Instrument i) { […]

Bruce Eckel’s Thinking in Java Contents | Prev | Next In Chapter 6 you saw how an object can be used as its own type or as an object of its base type. Taking an object handle and treating it as the handle of the base type is called upcasting because of the way inheritance […]

Bruce Eckel’s Thinking in Java Contents | Prev | Next Polymorphism is the third essential feature of an object-oriented programming language, after data abstraction and inheritance. It provides another dimension of separation of interface from implementation, to decouple what from how. Polymorphism allows improved code organization and readability as well as the creation of extensible […]

Bruce Eckel’s Thinking in Java Contents | Prev | Next Both inheritance and composition allow you to create a new type from existing types. Typically, however, you use composition to reuse existing types as part of the underlying implementation of the new type and inheritance when you want to reuse the interface. Since the derived […]

Bruce Eckel’s Thinking in Java Contents | Prev | Next is an object Although it is based on C++, Java is more of a “pure” object-oriented language. Both C++ and Java are hybrid languages, but in Java the designers felt that the hybridization was not as important as it was in C++. A hybrid language […]

Bruce Eckel’s Thinking in Java Contents | Prev | Next reusing the interface By itself, the concept of an object is a convenient tool. It allows you to package data and functionality together by concept, so you can represent an appropriate problem-space idea rather than being forced to use the idioms of the underlying machine. […]

Bruce Eckel’s Thinking in Java Contents | Prev | Next Create two classes, A and B, with default constructors (empty argument lists) that announce themselves. Inherit a new class called C from A, and create a member B inside C. Do not create a constructor for C. Create an object of class C and observe […]

Bruce Eckel’s Thinking in Java Contents | Prev | Next the implementation Once a class has been created and tested, it should (ideally) represent a useful unit of code. It turns out that this reusability is not nearly so easy to achieve as many would hope; it takes experience and insight to achieve a good […]

Bruce Eckel’s Thinking in Java Contents | Prev | Next It is helpful to break up the playing field into class creators (those who create new data types) and client programmers [4] (the class consumers who use the data types in their applications). The goal of the client programmer is to collect a toolbox full […]