Java编程预览.ppt

进行GUI设计时，除了使用前一章介绍的文字图形进行装饰外，更重要的是要使用窗体、按钮、文本框、选择框和滚动条等图形用户界面元素（统称为组件），以响应用户的动作，实现交互功能。 事件响应原理 委托事件模型 Swing组件的事件及监听者 一般步骤: Jlable组件 Jlable组件 Jlable组件 ?JButton组件 JButton类的常用成员方法 JButton类的构造方法 ActionEvent事件及其响应 3．事件响应 * Inner Class Listeners A listener class is designed specifically to create a listener object for a GUI component (e.g., a button). It will not be shared by other applications. So, it is appropriate to define the listener class inside the frame class as an inner class. * Inner Classes Inner class: A class is a member of another class. Advantages: In some applications, you can use an inner class to make programs simple. An inner class can reference the data and methods defined in the outer class in which it nests, so you do not need to pass the reference of the outer class to the constructor of the inner class. ShowInnerClass * Inner Classes, cont. * Inner Classes (cont.) Inner classes can make programs simple and concise. An inner class supports the work of its containing outer class and is compiled into a class named OuterClassName$InnerClassName.class. For example, the inner class InnerClass in OuterClass is compiled into OuterClass$InnerClass.class. * Inner Classes (cont.) An inner class can be declared public, protected, or private subject to the same visibility rules applied to a member of the class. An inner class can be declared static. A static inner class can be accessed using the outer class name. A static inner class cannot access nonstatic members of the outer class * Anonymous Inner Classes An anonymous inner class must always extend a superclass or implement an interface, but it cannot have an explicit extends or implements clause. An anonymous inner class must implement all the abstract methods in the superclass or in the interface. An anonymous inner class always uses the no-arg constructor from its superclass to create an instance. If an anonymous inner class implements an interface, the constructor is Object(). An anonymous inne