thisdemo.java

Java程序

class Point
{
protected int x,y;
 Point(int a,int b)
 {setPoint(a,b);}
 public void setPoint(int a,int b)
 {x=a;y=b;
 }
}
class Line extends Point
{protected int x,y;
 Line(int a,int b)
  { super(a,b);
   setLine(a,b);
  }
   public void setLine(int x,int y)
    {this.x=x+x;
     this.y=y+y;
    }
   public double length()
    {int x1=super.x,y1=super.y,x2=this.x,y2=this.y;
    return Math.sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
    }
   public String toString()
     {
	return "直线两点:["+super.x+super.y+"]["+x+"."+y+"]直线长度:"+this.length();
     }
}
public class ThisDemo
{
	public static void main(String args[])
	{Line line=new Line(20,20);
	System.out.println("\n"+line.toString());
        }
}