Java的面向对象编程(含外文出处)

Java的面向对象编程(含外文出处)(中文3300字,英文2000字)
摘要：本文简要的介绍了Java对象，面向对象编程的优点和方法。
关键字：Java对象 面向对象编程
Java的面向对象编程
软件的重用可以节省程序开发时间。它鼓励重复使用已经调试好的高质量的软件，从而减少系统运行后可能出现的问题。这些都是令人振奋的可能性。多态性允许我们用统一的风格编写程序，来处理多种已存在的类和特定的相关类。利用多态性我们可以方便地向系统中添加新的功能。继承和多态对于解决软件的复杂性是一种有效可行的技术。当创建一个新的类时，而不用完整的写出新的实例变量和实例方法，程序员会指定新的类继承已定义的超类的实例变量和实例方法。这个新的类被称为一个子类。每个子类本身将来亦可有新的子类，而其本身将成为父类。一个类的直接父类就是该类所直接继承的类（通过关键字extends继承）。一个间接超类是通过从两级或更多级以上的类继承而来的。例如，从类JApplet（包javax.swing中）扩展来的类Applet（包java.applet）。一个类单一的从一个父类继承而来。 Java不支持多重继承（而C++可以），但它支持接口的概念。接口可以使Java实现许多通过多重继承才能实现的优点而没有关联的问题。我们将在本章讨论的接口的详细内容。

Java Object-oriented programming
Software reusability saves time in program development. It encourages reuse of proven and debugged high-quality software, thus reducing problems after a system becomes operational. These are exciting possibilities. Polymorphism enables us to write programs in a general fashion to handle a wide variety of existing and yet-to-be-specified related  classes.Polymorphism makes it easy to add new capabilities to a system. Inheritance and polym-orphism are effective techniques for dealing with software complexity. When creating a new class, instead of writing completely new instance variables and instance methods, the programmer can designate that the new class is to inherit the instance variables and instance methods of a previously defined superclass. The new class is referred to as a subclass. Each subclass itself becomes a candidate to be a superclass for some future subclass. The direct superclass of a class is the superclass from which the class explicitly inherits (via the keyword extends).