testgeometricobject.java

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interface Colorable{
   public abstract String howToColor();
}
abstract class GeometricObject
{
 private String color="white";
 private boolean fill;
  protected GeometricObject()
 {
 }
  protected GeometricObject(String color,boolean fill)
 {this.color=color;
  this.fill=fill;
 }
 public void  setColor(String c)
 { this.color=c;
  }
 public String getColor()
 {return color;
 }
 public boolean isFill()
 {return fill;
  }
 public void setFill(boolean f)
 {this.fill=f;
 }
}
class Square extends GeometricObject implements Colorable{
    private double width;
    private double height;
    public Square(){
       this(1.0,1.0,"white",false);
    }
    public Square(double width,double height,String color,boolean filled){
        super(color, filled);
        this.width=width;
        this.height=height;
    }
    public double getWidth(){
        return width;
    }
    public void setWidth(double width){
         this.width=width;
    }
     public double getHeight(){
        return height;
    }
    public void setHeight(double height){
         this.height=height;
    }
    public String howToColor(){
        return "color it red";
    }
}
class Circle extends GeometricObject{
      private double radius;
      public Circle(){
        this(1.0,"white",false);
      }
      public Circle(double radius,String color,boolean filled){
        super(color,filled);
        this.radius=radius;
      }
      public double getRadius(){
         return radius;
      }
      public void setRadius(double radius){
           this.radius=radius;
      }
      public String howToColor(){
        return "color it green";
    }
}
public class TestGeometricObject{
      public static void main(String[] args){
          Object[]  objects={new Square(),new Circle()};
          for(int i=0;i<objects.length;i++)
              showObject(objects[i]);
      }
      public static void showObject(Object object){
          if(object instanceof Colorable)
                System.out.println(((Colorable)object).howToColor());
      
      }             
        
}