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1、实验五 继承与多态专业班级专业班级学学 号号姓姓 名名实验学时实验学时2实验类实验类 型型验证性验证性实验地实验地 点点软件工程实验 室实验时间实验时间2013-11-21指导老指导老 师师曹记东曹记东实验成绩实验成绩年 月 日 一、实验目的： 理解继承与多态的概念，掌握三种访问控制的区别，掌握抽象类、接口与包的应用。 二、实验内容： 1. 参考教材 P112，示例程序 C5_17，掌握抽象类的应用。 2. 参考教材 P116，示例程序 C5_19，掌握接口的使用方法。 3. 参考教材 P121，示例程序 C5_20，掌握包的使用方法。 三、实验要求： 1.完成示例程序的验证。 2.写出实验报
2、告。 四、实验步骤与结果：（由学生按照实验内容完成） 1. 示例程序示例程序 c5_17 import java.awt.*; import java.applet. *; abstract class Shapes /定义一个抽象类定义一个抽象类 Shapes public int x,y; /x、y 为画图的坐标为画图的坐标public int width,height;public Shapes(int x,int y,int width,int height) this.x=x;this.y=y;this.width=width;this.height=height;abstract
3、double getArea( ); /求图形面积的抽象方法求图形面积的抽象方法abstract double getPerimeter( ); /求图形周长的抽象方法求图形周长的抽象方法 class Square extends Shapes /由抽象类由抽象类 Shapes 派生的子类派生的子类矩形类矩形类 public double getArea( )return(width*height);public double getPerimeter( )return(2*width+2*height);public Square(int x,int y,int width,int heig
4、ht) super(x,y,width,height); class Triangle extends Shapes /由抽象类由抽象类 Shapes 派生的子类派生的子类三角形类三角形类 public double c; /斜边斜边public double getArea( )return(0.5*width*height);public double getPerimeter( )return(width+height+c);public Triangle(int x,int y,int base,int height)super(x,y,base,height);c=Math.sqrt
5、(width*width+height*height); class Circle extends Shapes /由抽象类由抽象类 Shapes 派生的子类派生的子类圆类圆类 public double r; /半径半径public double getArea( )return(r*r*Math.PI);public double getPerimeter( )return(2*Math.PI*r);public Circle(int x,int y,int width,int height)super(x,y,width,height);r=(double)width/2.0; publ
6、ic class c5_18 extends Applet /* */ private static final long serialVersionUID = -5589238944558587862L; Square Box=new Square(5,15,25,25);Triangle tri=new Triangle(5,50,8,4);Circle Oval=new Circle(5,90,25,25);public void paint(Graphics g) /画正方形画正方形g.drawRect(Box.x,Box.y,Box.width,Box.height);g.drawS
7、tring(“Box Area:“+Box.getArea( ),50,35);g.drawString(“Box Perimeter:“+Box.getPerimeter( ),50,55);g.drawString(“tri Area:“+tri.getArea( ),50,75);g.drawString(“tri Perimeter:“+tri.getPerimeter( ),50,95);g.drawOval(Oval.x,Oval.y,Oval.width,Oval.height); /画圆画圆g.drawString(“oval Area:“+Oval.getArea( ),50
8、,115); 2. 示例程序示例程序 C5_19 import java.awt.*; import java.applet.*; interface Shapes abstract double getArea( );abstract double getPerimeter( ); class Coordinates int x,y;public Coordinates(int x,int y)this.x=x;this.y=y; /Square Coordinates Shapes class Square extends Coordinates implements Shapes pub
9、lic int width,height;public double getArea( )return(width*height);public double getPerimeter( )return(2*width+2*height);public Square(int x,int y,int width,int height)super(x,y);this.width=width;this.height=height; class Triangle extends Coordinates implements Shapes public int width,height;public d
10、ouble c;public double getArea( )return(0.5*width*height);public double getPerimeter( )return(width+height+c);public Triangle(int x,int y,int base,int height)super(x,y);width=base;this.height=height;c=Math.sqrt(width*width+height*height); class Circle extends Coordinates implements Shapes public int
11、width,height;public double r;public double getArea( )return(r*r*Math.PI);public double getPerimeter( )return(2*Math.PI*r);public Circle(int x,int y,int width,int height)super(x,y);this.width=width;this.height=height;r=(double)width/2.0; public class c5_20 extends Applet /* */ private static final lo
12、ng serialVersionUID = 2664639751369334604L; Square Box=new Square(5,15,25,25);Triangle tri=new Triangle(5,50,8,4);Circle Oval=new Circle(5,90,25,25);public void paint(Graphics g)g.drawRect(Box.x,Box.y,Box.width,Box.height);g.drawString(“Box Area:“+Box.getArea( ),50,35);g.drawString(“Box Perimeter:“+Box.getPerimeter( ),50,55);g.drawString(“tri Area:“+tri.getArea( ),50,75);g.drawString(“tri Perimeter:“+tri.getPerimeter( ),50,95);g.drawOval(Oval.x,Oval.y,Oval.width,Oval.height);g.drawString(“oval Area:“+Oval.getArea( ),50,115); 五.总结
