继承与抽象编程

实验五、继承与抽象编程1实验目的（1）理解抽象类的意义和实际应用的一般模式，熟练掌握抽象类和抽象方法的定义以及抽象类的继承，尤其是子类是非抽象类的情况。2实验内容和步骤（1） 设计一个抽象形状类Shape，包含一个getArea()抽象方法。（2） 在Shape类基础上设计圆形、矩形、三角形和梯形四个子类，要求根据实际形状重写getArea()方法。abstract class Shapeprotected String name;public Shape(String xm)name = xm;System.out.print(名称:+name);abstract public double getArea();class Circle extends Shapeprivate final double PI = 3.14;private double radius;public Circle(String shapeName,double r)super(shapeName);radius = r;public double getArea()return PI*radius*radius;class Rectangle extends Shapeprivate double width;private double height;public Rectangle(String shapeName,double width,double height)super(shapeName);this.width = width;this.height = height;public double getArea()return width*height;class Trapezoid extends Shapeprivate double height;private double topline;private double baseline;public Trapezoid(String shapeName,double height,double topline,double baseline)super(shapeName);this.height = height;this.topline = topline;this.baseline = baseline;public double getArea()return height*(topline+baseline)/2;class Trangle extends Shapeprivate double baseline;private double height;public Trangle(String shapeName,double height,double baseline)super(shapeName);this.height = height;this.baseline = baseline;public double getArea()return height*baseline/2;public class ABpublic static void main(String args)Shape circle = new Circle(圆,5.0);System.out.print(;面积=+circle.getArea();System.out.print(n);Shape rect= new Rectangle(矩形,3.0,5.0);System.out.print(;面积=+rect.getArea();System.out.print(n);Shape trangle = new Trangle(三角形,4.2,5.5);System.out.print(;面积=+trangle.getArea();System.out.print(n);Shape trapezoid =new Trapezoid(梯形,5.0,4.0,9.0);System.out.print(;面积=+trapezoid.getArea();System.out.print(n);（3） 设计一个TestShape类，包含变量area（存储总面积）、静态方法countArea(Shape s)，该方法负责把参数中的形状面积加入到area中。在main函数中新建（2）中四种类型的对象s1、s2、s3、s4，通过调用countArea方法把四个对象面积累加到area中，最后输出area。（4） 将形状类Shape改为接口，在不修改测试类TestShape的基础上，保证执行TestShape能够得到与实验四同样的结果。interface IShapefinal double PI = 3.14;abstract public double getArea();class Circle implements IShapedouble radius;public Circle(double r)radius = r;public double getArea()return PI*radius*radius;class Rectangle implements IShapeprivate double width;private double height;public Rectangle(double width,double height)this.width = width;this.height = height;public double getArea()return width*height;class Trapezoid implements IShapeprivate double height;private double topline;private double baseline;public Trapezoid(double height,double topline,double baseline)this.height = height;this.topline = topline;this.baseline = baseline;public double getArea()return height*(topline+baseline)/2;class Trangle implements IShapeprivate double baseline;private double height;public Trangle(double height,double baseline)this.height = height;this.baseline = baseline;public double getArea()return height*baseline/2;public class ABCDpublic static void main(String args)IShape circle = new Circle(3.0);System.out.print(圆面积=+circle.getArea();System.out.print(n);Rectangle rect = new Rectangle(2.5,3.2);System.out.print(矩形面积=+rect.getArea();System.out.print(n);Trapezoid trapezoid =new Trapezoid(5.0,6.0,9.0