circle.java

（1） 实现一个Point类

package p2;
import p1.point;	    

	
public class Circle{
	public	int r;
	public	point center=new point();
	  public  Circle(){
	   

        }
       public Circle(int xx,int yy,int r){
	             center.x=xx;
                  center.y=yy;
                  this.r=r;
        }
        
       public Circle(point p,int r)
        {
        	center.x=p.x;
        	center.y=p.y;
     	this.r=r;
        	}
       public double area()
        {return (this.r*this.r*Math.PI);
        	}
       public	double perimeter()
       	{return (2*this.r*Math.PI);
       		}
       public int relation(Circle c){
		if(this.r==c.r&&center.x==c.center.x&&center.y==c.center.y)return 0;
		 else if((center.x==c.center.x)&&(center.y==c.center.y))  return 1;
		 else if(center.distance(c.center)<(this.r+c.r))return 2;
		 else if(center.distance(c.center)>(this.r+c.r))return 3;
		 else return 4;
		 }
	
	}