类名+函数名（参数1，参数2.....）{.......return this;}

 1 import java.awt.Point;
 2   class rectangle
 3     { int x1=0;
 4       int y1=0;
 5       int x2=0;
 6       int y2=0;
 7      
 8      rectangle point(int x,int y,int z,int w)
 9       {x1= x;
10        y1= y;
11        x2= z;
12        y2= w;
13        return this;
14        }
15      rectangle point(Point topleft,Point rightbottom)
16       {x1=topleft.x;
17        y1=topleft.y;
18        x2=rightbottom.x;
19        y2=rightbottom.y;
20        return this;
21         }
22       rectangle point(Point topleft,int w,int h)
23        { x1= topleft.x;
24          y1= topleft.y;
25          x2= topleft.x + w;
26          y2= topleft.y - h;
27         return this;
28         }
29       public static void main(String[] args)
30 
31        { rectangle experiment = new rectangle();
32          experiment.point(1,2,3,4);
33          System.out.print(experiment.x1+" "+experiment.y1+" "+experiment.x2+" "+experiment.y2);
34          experiment.point(new Point(1,2),new Point(3,4));
35          System.out.print(experiment.x1+" "+experiment.y1+" "+experiment.x2+" "+experiment.y2);
36          experiment.point(new Point(1,2),3,4);
37          System.out.print(experiment.x1+" "+experiment.y1+" "+experiment.x2+" "+experiment.y2);
38         }
39    
40    }