C#面向对象程序设计 教学课件 郑宇军 CSCH5.ppt

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1、1第5章继承和多态继承基类和派生类自顶向下的分解自底向上的抽象2图形飞机汽车轮船交通工具继承基类和派生类.NET类库3继承基类和派生类4publicclassAutomobile{privatefloatspeed=100;publicfloatRun(floatdistance){returndistance/speed;}}publicclassBus:Automobile{}Automobilea1=newAutomobile();a1.Run(1000);Busb1=newBus();b1.Run(1000);继承对

2、象的生命周期构造析构5publicclassVehicle{}publicclassAutomobile:Vehicle{}publicclassCar:Automobile{}publicclassLimousine:Car{}newVehicle()newAutomobile()newCar()newLimousine()~Vehicle()~Automobile()~Car()~Limousine()多态性基类：普通成员派生类：覆盖成员6publicclassAutomobile{protectedfloatspeed

3、;protectedfloatweight;publicfloatRun(floatdistance){returndistance/speed;}}publicclassCar:Automobile{publicnewfloatRun(floatdistance){return(1+weight/100)*distance/speed;}}多态性覆盖：根据声明类型决定成员调用7Automobilea1=newTruck();a1.Run(1000);Cara2=newCar();a2.Run(1000);Automobil

4、e.RunCar.Run多态性基类：虚拟成员8publicclassAutomobile{protectedfloatspeed;protectedfloatweight;publicvirtualfloatRun(floatdistance){returndistance/speed;}}多态性基类：虚拟成员派生类：重载成员9publicclassTruck:Automobile{privatefloatload;publicoverridefloatRun(floatdistance){returnbase.Run(1+

5、(load+weight)/100);}}publicclassCar:Automobile{publicoverridefloatRun(floatdistance){return(1+weight/100)*distance/speed;}}多态性重载：根据实际类型决定成员调用10Automobilea1=newCar();a1.Run(1000);Automobilea2=newTruck();a2.Run(1000);Car.RunTruck.Run多态性抽象类和抽象方法11publicabstractclassAu

6、tomobile{protectedfloatspeed;protectedfloatweight;publicabstractfloatRun(floatdistance);}Automobilea1=newAutomobile();多态性抽象类和抽象方法12publicclassTruck:Automobile{privatefloatload;}多态性抽象类和抽象方法13publicclassTruck:Automobile{privatefloatload;publicoverridefloatRun(floatdi

7、stance){returnbase.Run(1+(load+weight)/100);}}多态性密封类和密封方法14publicclassBigTruck:Truck{}publicsealedclassTruck:Automobile{privatefloatload;publicoverridefloatRun(floatdistance){returnbase.Run(1+(load+weight)/100);}}多态性密封类和密封方法15publicclassBigTruck:Truck{publicoverrid

8、efloatRun(floatdistance){returnbase.Run(1+2*(load+weight)/100);}}publicclassTruck:Automobile{privatefloatload;publicsealedfloatRun(floatdistance)