实现Comparable接口的Circle类

2）内部设计

Circle类和Rectangle类中覆盖了定义在GeometricObject类中的getArea()和getPerimeter()方法。语句： GeometricObject geoObject1=new Circle(5);

GeometricObject geoObject2=new Rectangle(5,3);

创建了一个新圆和一个新矩形，并把它们赋值给变量geoObject1和geoObject2。这两个变量都是GeometricObject类型的。

当调用equalArea(geoObject1,geoObject2)时，由于geoObject1是一个圆，所以object1.getArea()使用的是Circle类定义的getArea()方法，而geoObject2是一个矩形，所以object2.getArea()使用的是Rectangle类的getArea()方法。

类似地，当调用displayGeometricObject(geoObject1),使用在Circle类中定义的getArea和getPerimeter方法，而当调用displayGeometricObject(geoObject2)时,使用的是在Rectangle类中定义的getArea和getPerimeter方法。 六、完整源码

实现Comparable接口的Circle类

a、 运用继承和多态

1）GeometricObject.Java

package yuan1;

public class GeometricObject {

private String color =\; private boolean filled;

private java.util.Date dateCreated; public GeometricObject(){ }

public GeometricObject(String color,boolean filled){

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dateCreated = new java.util.Date();

}

}

dateCreated = new java.util.Date(); this.color = color; this.filled = filled;

public String getColor(){ }

public void setColor(String color){ }

public boolean isFilled(){ }

public void setFilled(boolean filled){ }

public java.util.Date getDateCreated(){ }

public String toString(){ }

return\+dateCreated+\+color+\+filled; return dateCreated; this.filled = filled; return filled; this.color = color; return color;

2) Circle.java

package yuan1;

public class Circle extends GeometricObject{

private double radius; public Circle(){ }

public Circle(double radius){ }

public Circle(double radius,String color,boolean filled){ }

public double getRadius(){ }

public void setRandius(double radius){ }

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this.radius =radius;

this.radius =radius; setColor(color); setFilled(filled);

return radius;

this.radius =radius;

}

public double getArea(){ }

public double getDiameter(){ }

public double getPerimeter(){ }

public void printCircle(){ }

System.out.println(\+getDateCreated()+\return 2*radius*Math.PI; return 2*radius;

return radius*radius*Math.PI;

radius is\+radius);

3) Rectangle.java

package yuan1;

public class Rectangle extends GeometricObject{

private double width; private double height; public Rectangle(){ }

public Rectangle(double width,double height){ }

public Rectangle(double width,double height,String color,boolean filled){ }

public double getWidth(){ }

public void setWidth(double width){ }

public double getHeight(){ }

public void setHeight(double height){ }

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this.width=width; this.height=height;

this.width=width; this.height=height; setColor(color); setFilled(filled);

return width;

this.width=width;

return height;

this.height=height;

}

public double getArea(){ }

public double getPerimeter(){ }

return 2*(width+height); return width*height;

4) TestCircleRectangle.java

package yuan1;

public class TestCircleRectangle { }

public static void main(String[]args){ }

Circle circle=new Circle(1);

System.out.println(\+circle.toString()); System.out.println(\+circle.getRadius()); System.out.println(\+circle.getArea());

System.out.println(\+circle.getDiameter()); Rectangle rectangle=new Rectangle(2,4);

System.out.println(\+rectangle.toString()); System.out.println(\+rectangle.getArea());

System.out.println(\+rectangle.getPerimeter());

a、 运用继承和多态

1）GeometricObject.Java

package yuan;

public abstract class GeometricObject {

private String color =\; private boolean filled;

private java.util.Date dateCreated; protected GeometricObject(){ }

protected GeometricObject(String color,boolean filled){ }

public String getColor(){ }

public void setColor(String color){

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dateCreated = new java.util.Date();

dateCreated = new java.util.Date(); this.color = color; this.filled = filled;

return color;

}

}

this.color = color;

public boolean isFilled(){ }

public void setFilled(boolean filled){ }

public java.util.Date getDateCreated(){ }

public String toString(){ }

public abstract double getArea(); public abstract double getPerimeter();

return\+dateCreated+\+color+\+filled; return dateCreated; this.filled = filled; return filled;

2) Circle.java

package yuan;

public class Circle extends GeometricObject{

private double radius; public Circle(){ }

public Circle(double radius){ }

public Circle(double radius,String color,boolean filled){ }

public double getRadius(){ }

public void setRandius(double radius){ }

public double getArea(){ }

public double getDiameter(){ }

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this.radius =radius;

this.radius =radius; setColor(color); setFilled(filled);

return radius;

this.radius =radius;

return radius*radius*Math.PI;

return 2*radius;