面向对象技术及语言-第8章

面向对象技术及语言
Object-Oriented Technology & Language 第 8章 Interface & Inner Classes
主讲教师： 饶若楠 上海交通大学计算机科学与工程系 rao-ruonan@
第 8章
Interfaces & Inner Classes
You can add new method declarations to an interface by using inheritance, and you can also combine several interfaces into a new interface with inheritance.
Example: c08: Parcel1.java (p331)
Inner classes and upcasting (p333-p335)
Inner classes really come into their own when you start upcasting to a base class, and in particular to an interface.
Example: c08: Months.java (p324) c08: Month.java (p325)
Initializing fields in interfaces (p327 -328)
Fields defined in interfaces are automatically static and final. Those cannot be “blank finals,” but they can be initialized with nonconstant expressions.

8.1 接口(Interface)
所谓接口就是对操作规范的说明。通俗地说， 接口只是说明函数应该做什么(What),但没有定 义函数如何做（How)
<<Interface>> Shape draw ()
Shape
Triangle Elided/Iconic Representation (“lollipop”) draw ()
Example: c08: LocalInnerClass.java (p352)
Inner class identifier (p354)
LocalInnerClass$2.class
“multiple inheritance” in Java (p319 -323)
Because an interface has no implmentation at all - that is, there is no storage associated with an interface - there’s nothing to prevent may interfaces from being combined.
Referring to the outer class object (p347-p348)
Example: c08: Parcel11.java (p347)
Reaching outward from a multiply-nested class(p348-p349)
Example: c08: MultiNestingAccess.java (p348)
Example: c08: NestingInterfaces.java (p328)
Inner classes (p331-p333)
It’s possible to place a class definition within another class definition. This is called an inner class.
5.9 接口Interface
3. 接口可以作为一种引用类型来使用。任何实现
该接口的类的实例都可以存储在该接口类型的变 量中，通过这些变量可以访问类所实现的接口中 的方法。Java运行时系统动态地确定该使用哪个 类中的方法。
例如： Shape abc = new Triangle();
8.1接口Interface - 例子
8.1 接口Interface - 例子
class InterfaceType{ public static void main( String args[] ){ Collection c = new FIIFOQueue(); …… add( obj ); }…… }
把接口作为一种数据类型可以不需要了解 对象所对应的具体的类，而着重于它的交互 界面
Example: c08: Adventure.java (p320)
Name collision when combining interfaces Example: c08: InterfaceCollision.java (p322)
Extending an interface with inheritance (p323 -324)
Inheriting from inner classes (p349)
Example: c08: InheritInner.java (p349)
Can inner classes be overriden ?(p350)
Example: c08: BigEgg.java (p350)
Local inner classes (p352)
第 8章

Interfaces & Inner Classes
8.2.6 Referring to the outer class object 8.2.7 Reaching outward from a multiply-nested class 8.2.8 Inheriting frominner classes 8.2.9 Can inner classes be overriden 8.2.10 Local inner classes 8.2.11 Inner class identifiers 8.3 Why inner classes? 8.3.1 Closure & Callbacks 8.3.2 Inner classes & control frameworks
Example: c08: Destination.java (p333) c08: Contents.java (p334) c08: TestParcel.java (p334)
Inner classes in methods and scopes (p335-p338)
Inner classes can be created within a method or even an arbitrary scope.
interface Collection { int MAX_NUM=100; void add (Object obj); void delete (Object obj); Object find (Object obj); int currentCount ( ); class FIFOQueue implements collection{ } void add ( Object obj ){……} void delete( Object obj ){……} Object find( Object obj ){……} int currentCount{……} }
Example: c08: sequence.java (p342)
Nested classes (p344-p347)
static inner classes.
Example: c08: Parcel10.java (p345) c08: IInterface.java (p346) c08: TestBed.java (p346)
draw()
Rectangle draw ()
Triangle draw ()
Rectangle draw ()ห้องสมุดไป่ตู้
8.1 接口Interface
1. 接口的定义
接口的定义包括接口声明和接口体两部分。如下： [public] interface InterfaceName [extends superInterfaceList] {//接口声明 type constantName = Value; //常量声明，可为多个 retumType methodName ( [paramList] ); //方法声明，可为多个 }
Example: c08: HorrorShow.java (p323)
Grouping constants (p324 -327)
Because any fields you put into an interface are automatically static and final, the interface is a convenient tool for creating groups of constant.
8.1 Interfaces 8.1.1 “multiple inheritance” in Java 8.1.2 Extending an interface with inheritance 8.1.3 Grouping constants 8.1.4 Initializing fields in interfaces 8.1.5 Nesting interfaces 8.2 Inner Classes 8.2.1 Inner classes and upcasting 8.2.2 Inner classes in methods and scopes 8.2.3 Anonymous inner classes 8.2.4 The link to the outer class 8.2.5 Nested classes