java - Multiple calls of paintComponent() -

i have these 2 classes:

public class pencil extends jcomponent implements mouselistener, mousemotionlistener{ plansa plansa; graphics g; public pencil(plansa newcanvas){     this.plansa = newcanvas;     this.plansa.setflagshape(false); } @override public void mousedragged(mouseevent arg0) {     plansa.setmousedragged(arg0);     this.plansa.setflagshape(false);     plansa.paintcomponent(plansa.getgraphics()); }  @override public void mouseclicked(mouseevent e) { }  @override public void mousepressed(mouseevent arg0) {     plansa.setmousepressed(arg0); }  @override public void mousereleased(mouseevent arg0) {     // todo auto-generated method stub     plansa.setmousereleased(arg0);     this.plansa.setflagshape(true);     plansa.paintcomponent(plansa.getgraphics());  }  @override public void mouseentered(mouseevent e) { }  @override public void mouseexited(mouseevent e) { }  @override public void mousemoved(mouseevent e) { }  } 

and one:

public class plansa extends jpanel{ image image; pencil pencil;  //...  void init(){     this.setshape("freeline");     this.setcolor(color.black);     this.size=1;     this.type="round";     this.fill=false;     this.setbackground(color.white);     pencil = new pencil(this);     addmouselistener(pencil);     addmousemotionlistener(pencil);     flagpaint = true;     flagshape = false; } public plansa(){     this.setsize(800, 600);     init(); }  //...         @override     public void paintcomponent(graphics g) {     g.setcolor(currentcolor);     graphics2d g2d = (graphics2d) g;     g2d.setstroke(setbrush(size,type));     super.paintcomponent(g);     switch(shape){         default: break;         case "freeline":{              g.drawline(xdragged, ydragged, xcurrent, ycurrent);              break;         }             case "rectangle":{                 if(flagshape == true){             g.drawrect(xpressed, ypressed, math.max(xcurrent-xpressed,xpressed-xcurrent), math.max(ycurrent-ypressed,ypressed-ycurrent));             if(fill == true) g.fillrect(xpressed, ypressed, math.max(xcurrent-xpressed,xpressed-xcurrent), math.max(ycurrent-ypressed,ypressed-ycurrent));                 }             break;         }         case "circle":{             if(flagshape == true){             int radius = (int)math.sqrt(math.max(xcurrent-xpressed,xpressed-xcurrent)*math.max(xcurrent-xpressed,xpressed-xcurrent)+math.max(ycurrent-ypressed,ypressed-ycurrent)*math.max(ycurrent-ypressed,ypressed-ycurrent));             g.drawoval(xpressed, ypressed, radius, radius);             if(fill == true) g.filloval(xpressed, ypressed, radius, radius);             }             break;         }         case "oval":{             if(flagshape == true){             g.drawoval(xpressed, ypressed, math.max(xcurrent-xpressed,xpressed-xcurrent), math.max(ycurrent-ypressed,ypressed-ycurrent));             if(fill == true) g.filloval(xpressed, ypressed, math.max(xcurrent-xpressed,xpressed-xcurrent), math.max(ycurrent-ypressed,ypressed-ycurrent));             }             break;         }         case "line":{             if(flagshape == true){             g.drawline(xpressed, ypressed, xcurrent, ycurrent);             }             break;         }     }  }   //... } 

my problem every time call paintcomponent() method, jpanel clears , item remains 1 drawn. there way avoid this?

store objects in arraylist , iterate through when drawing.

you have them implement custom interface, drawable example, store in arraylist<drawable>.