triangle.java

这个是java设计模式的文件 可能对了解设计思想有一定帮助

import java.awt.*;
public abstract class Triangle
{
  Point p1, p2, p3; 
  //---------------------------------------
  public Triangle(Point a, Point b, Point c)
  {
     //save
     p1 = a; p2 = b; p3 = c;
  }
  //---------------------------------------
  public void draw(Graphics g)
  {
   //This routine draws a general triangle
     drawLine(g, p1, p2);
     Point current = draw2ndLine(g, p2, p3);
     closeTriangle(g, current);
  }
  //---------------------------------------
  public void drawLine(Graphics g, Point a, Point b)
  {
     g.drawLine(a.x, a.y, b.x, b.y);
  }
  //---------------------------------------
  //this routine is the "Hook" that has to be implemented
  //for each triangle type.
  abstract public Point draw2ndLine(Graphics g, Point a, Point b);
  //---------------------------------------
  public void closeTriangle(Graphics g, Point c)
  {
     //draw back to first point
     g.drawLine(c.x, c.y, p1.x, p1.y);
  }

}