面向对象技术及语言-第8章

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: RandVals.java (p327) c08: TestRandvals.java (p327)
Nesting interfaces (p328 -331)
Interfaces may be nested within classes and within other interfaces.
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)
“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.
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.
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@cs.sjtu.edu.cn
第 8章
Interfaces & Inner Classes
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: 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.
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
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.
例 如 ： interface Shape {public void draw(); } 一个接口可以有多个父接口，用逗号隔开，子接口 继承父接口中所有的常量和方法。
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8.1 接口Interface 2. 接口的实现
在类的声明中用 implements 子句来表示一个类使用某个 接口，在类体中可以使用接口中定义的常量，而且必须实 现接口中定义的所有方法。一个类可以实现多个接口，在 implements 子 句 中 用 逗 号 分 隔 。 例 如 ： public class Triangle implements public void draw() {…..} } Shape {
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
Example: c08: Adventure.java (p320)
Name collision when combining interfaces Example: c08: InterfaceCollision.java (p322)
Extending an interface with inheritance (p323 -324)
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
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: Wrapping.java (p336) c08: Parcel4.java (p336) c08: Parcel5.java (p334)
Anonymous inner classes (p338-p342)
Example: c08: c08: c08: c08: c08: Parcel6.java (p338) Parcel7.java (p339) Parcel8.java (p339) AnonymousConstructor.java (p340) Parcel9.java (p341)
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.
The link to the outer class (p342-p344)
When you create an inner class, an object of that inner class has a link to the enclosing object that made it.
Example: c08: LocalInnerClass.java (p352)
Inner class identifier (p354)
LocalInnerClass$2.class
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.
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)

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 ()
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.
draw()
Rectangle draw ()
Triangle draw ()
Rectangle draw ()
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 }