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);
         }

    }