程序员玩转算法清华教程

33象的程序设计方掌握类、对象的基本学习目455了677认识系统<--->问题空间<--->解决空面面象80年代初的定义面•899式 基本思对象：性和从更抽象的角度看对对象提供了的抽象描述，其包类实例化-->对象抽象化-->类的基本概封封 的— 封封封装的原则在上的反映是：要求使部错误对它的“交叉”，使错误部存取和的程度。 继继例如轮船、客轮；人类通常称一般类为父类（superclass,超 point.draw();消 main主动对面面OOA－ObjectOOD－ObjectOrientedOOI－ObjectOrientedJava语言的面对象特第类类 |final]classclassName[extendssuperclassName][implements//成员方}[public|protected|private[static][final][transient][volatile]type [public|protected|private[static][final| ][native][synchronized]returnTypemethodName([paramList])[throwsexceptionList]{class类[public|protected|private[static][final][transient][volatile]type static:静态变量（ 常transient: 成员[public|protected|private][static][final| native]synchronized]returnTypemethodName([paramList])[throwsexceptionList] //方法方 类方法，可通过类名直接调 抽象方法，没有方法 方法不能 集成其它语言的 控制多个并发线成员方法成员方法(值参传递publicclassPassTest{floatpublicstaticvoidmain(String{intPassTestpt=ne System.out.println(“OriginalInt成员方法(值参传递System.out.pringln(“IntValueafterChangeis:”+val);System.out.println(“ptValueafterChange 成员方法成员方法(值参传递publicvoidvalue){}publicvoidchangeObjValue(PassTestref){ref.ptValue=99f;} OriginalIntValueis:11IntValueafterChangeis:OriginalptValueis:101.0ptValueafterChangeis:99.0成员方法(值参传递成员方法成员方法(方法体。 成员方法(方法体例classintx=0,y=0,z=0; voidinit(intx,inty){this.x=x;intz=5; System.out.println(“**ininit**”);System.out.(“x=”+x+“y=”+y+“成员方法成员方法(方法体publicclassVariableTest{publicstaticvoidmain(Stringargs[]){Variablev=newVariable();System.out.println(“**beforeinit**”);System.out.println(“x=”+v.x+“y=”+ 成员方法(方法体System.out.println(“x=”+v.x+“y=”+}}成员方法成员方法(方法体c:\>java**beforeinit**x=0 **ininit**x=20y=30z=5**afterinit**x=20y=30z=0它的值是调用该方法的对象当前对象 成员方法(方法体方法重载方法重载(Method例MethodOverloading{voidreceive(inti){……}voidreceive(intx,inty){……}voidreceive(doubled){……}voidreceive(Strings){……}}方法重publicMethodOverloadingTest{publicstaticvoidmain(Stringargs[]){mo.receive(“veryinteresting,isn’t}方法重ReceiveoneintdataReceivetwointdatas ReceiveonedoubledataReceiveas=veryinteresting,isn’t}Point(intx,intthis.x=x; }例Point{int构造方对对象进 收集前，系统自动调protectedvoidfinalize()throwsthrowable……//cleanupcodeforthisclass}对对publicclassoWorldApp{publicstaticvoidmain(String{ }} 生使清空间包 、实例化和初始格式typeobjectName=new：type 它有关数据类型的信息以及当前对 问和例：p.xtx=newPoint(//statementswhen}调用对象的方格式newPoint(if(p.equal(20,30)) //statementswhen}…封装继承多态象特面class{[public|protected|private[static][final][transient][volatile]type [public|protected|private[static][final| ][native][synchronized]returnTypemethodName([paramList])[throwsexceptionList] //}******protected* 修饰词根类： 格式classSubClassextendsSuperClass…}创建子SuperClass{intx;…voidsetX( x=0;}}classSubClassextendsSuperClass{intx; //hidexin…voidsetX(){//overridemethodsetX()x=5;} 重super }SuperClass{intx;SuperClass({}voiddoSomething()}classSubClassextends{intSubClass()super(); //callconstructorofsuperclass //super(要放在方法中的第一句System.out.println(“inSubClass:x=“+x);}voiddoSomething()super.doSomething();//callmethodofsuperclass }}publicclassinheritancepublicstaticvoidmain(String{SubClasssubC=newSubClass();} inSuperClass:x=3inSubClass: inSubClass.doSomething()super.x=3sub.x=5调用规则：根据实例voidcallme() }classBA{voidcallme(){ }publicclasspublicstaticvoidmain(String{Aa=newa.callme(}}重写方法的调用规c:\>javaInsideB’scallme() 方法重写应遵循的原classpublicvoidfunction()}}classChildextendsParent{privatevoidfunction()} publicclassOverriddenTest{publicstaticvoidmain(String{Parent }p2.function();}}对象状态的确定Manager和Contractor都是Employee的子publicvoidmethod(Employee{if(einstanceof…//dosomethingasa elseif(einstanceofContractor)…}//dosomethingasaContractorelse{ //dosomething}finalfinalfinaltypevariableName;finalreturnType…}finalclass…}final关键statictypestaticreturnTypeclassMethod({paramlist])…}类变通过对象 这些实例变实例变量和类变类方法中不能使用this或类实例方法和类方例class{staticintclassVar;intstaticvoidsetClassVar(int{// //can’taccessnostaticstaticint{returnclassVar;}{classVar=i; instanceVar=i;}intgetInstanceVar({returninstanceVar;}实例方法和类方publicclasspublicstaticvoidmain(String{Memberm1=newMember();Memberm2=newMember();}}实例方法和类方c:\>java 类类 :比较两个对象 〕是否相 来修 Class{ 用接接用接包括接 和接口完整的接口listOfSuperInterface]{…}常量定义:typeNAME=value;该常量被实现该接口的多个类共享具有public,finalstatic方法体定义:(具有public和 returnTypemethodName([paramlist]) }例interfaceintvoidadd(Objectobj);voiddelete(Objectobj);Objectfind(ObjectintcurrentCount(接口定voiddelete(Objectobj){…Objectfind(Objectobj){…}intcurrentCount{…} {… }classInterfaceTypepublicstaticvoidmain(String{Collectionc=new…}接口类型的使InnerInner•类: importjava.awt.*;importjava.awt.*;publicclass{privateFramef;privateTextFieldtf;publicstaticvoidmain(String{TwoListenInnerthat=newTwoListenInner(); InnerInnerInnerpublicvoidgo()f=newFrame(“Twolistenersf.add(“North”,newLabel(“Clickanddragthetf=newTextField(30); publicclassMouseEventHandlerextendsMouseAdapter{…}}publicclassMouseMotionHand