继承与多态实验报告.doc

实验五 继承与多态专业班级学 号姓 名实验学时2实验类型验证性实验地点软件工程实验室实验时间2013-11-21指导老师曹记东实验成绩 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c5_17import java.awt.*;import java.applet. *;abstract class Shapes /定义一个抽象类Shapes public int x,y; /x、y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 double getArea( ); /求图形面积的抽象方法 abstract double getPerimeter( ); /求图形周长的抽象方法class Square extends Shapes /由抽象类Shapes派生的子类矩形类 public double getArea( )return(width*height); public double getPerimeter( )return(2*width+2*height); public Square(int x,int y,int width,int height) super(x,y,width,height); class Triangle extends Shapes /由抽象类Shapes派生的子类三角形类public double c; /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(width*width+height*height); class Circle extends Shapes /由抽象类Shapes派生的子类圆类public double r; /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; public 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 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); /画圆 g.drawString(oval Area:+Oval.getArea( ),50,115); 2. 示例程序C5_19import 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 Shapesclass Square extends Coordinates implements Shapes public 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 double 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 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 long 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 Are