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

下述的函数是这样定义的： 类名+函数名（参数1，参数2.....）{.......return this;}

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

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

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

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

                                   int[]+函数名（参数1，参数2.....）{.......return int[];}

                                   String[]+函数名（参数1，参数2.....）{.......return String[];} 

                                   void+函数名（参数1，参数2.....）{...................................} 

import java.awt.Point;
  class rectangle
    { int x1=0;
      int y1=0;
      int x2=0;
      int y2=0;
     
     rectangle point(int x,int y,int z,int w)
      {x1= x;
       y1= y;
       x2= z;
       y2= w;
       return this;
       }
     rectangle point(Point topleft,Point rightbottom)
      {x1=topleft.x;
       y1=topleft.y;
       x2=rightbottom.x;
       y2=rightbottom.y;
       return this;
        }
      rectangle point(Point topleft,int w,int h)
       { x1= topleft.x;
         y1= topleft.y;
         x2= topleft.x + w;
         y2= topleft.y - h;
        return this;
        }
      public static void main(String[] args)

       { rectangle experiment = new rectangle();
         experiment.point(1,2,3,4);
         System.out.print(experiment.x1+" "+experiment.y1+" "+experiment.x2+" "+experiment.y2);
         experiment.point(new Point(1,2),new Point(3,4));
         System.out.print(experiment.x1+" "+experiment.y1+" "+experiment.x2+" "+experiment.y2);
         experiment.point(new Point(1,2),3,4);
         System.out.print(experiment.x1+" "+experiment.y1+" "+experiment.x2+" "+experiment.y2);
        }
   
   }