swing - Java paintComponent as a JComponent -

don't know if specific title, have asked question has gone dead. trying execute paintcomponent() can draw rectangles, triangles , more class being jcomponent.

here code far:

public class design extends jcomponent { private static final long serialversionuid = 1l;  private list<shapewrapper> shapesdraw = new arraylist<shapewrapper>(); private list<shapewrapper> shapesfill = new arraylist<shapewrapper>();  graphicsdevice gd =     graphicsenvironment.getlocalgraphicsenvironment().getdefaultscreendevice(); int screenwidth = gd.getdisplaymode().getwidth(); int screenheight = gd.getdisplaymode().getheight();  public void paintcomponent(graphics g) {     super.paintcomponent(g);     graphics2d g2d = (graphics2d) g;     for(shapewrapper s : shapesdraw){         g2d.setcolor(s.color);         g2d.draw(s.shape);     }     for(shapewrapper s : shapesfill){         g2d.setcolor(s.color);         g2d.fill(s.shape);     } }  public void drawrect(int xpos, int ypos, int width, int height) {     shapesdraw.add(new rectangle(xpos, ypos, width, height));     repaint(); }  public void fillrect(int xpos, int ypos, int width, int height) {     shapesfill.add(new rectangle(xpos, ypos, width, height));     repaint(); }  public void drawtriangle(int leftx, int topx, int rightx, int lefty, int topy, int righty) {     shapesdraw.add(new polygon(             new int[]{leftx, topx, rightx},             new int[]{lefty, topy, righty},             3));     repaint(); }  public void filltriangle(int leftx, int topx, int rightx, int lefty, int topy, int righty) {     shapesfill.add(new polygon(             new int[]{leftx, topx, rightx},             new int[]{lefty, topy, righty},             3));     repaint(); }   public dimension getpreferredsize() {     return new dimension(getwidth(), getheight()); }  public int getwidth() {     return screenwidth; } public int getheight() {     return screenheight; }  }  class shapewrapper {      color color;     shape shape;      public shapewrapper(color color , shape shape){         this.color = color;         this.shape = shape;     } } 

as shown above, works fine, except being able choose colour. want able define rectangles , triangles respective positions , lengths want add colour it.

but error.

the error says:

the method add(shapewrapper) in type list< shapewrapper > not applicable arguments (rectangle)

and:

the method add(shapewrapper) in type list< shapewrapper > not applicable arguments (polygon)

please help! stressed trying figure out blocking me doing many things.

the answer pretty basic...shape not type of shapewrapper, therefore can't added list decalred list<shapewrapper>

what should doing instead of

shapesdraw.add(new rectangle(xpos, ypos, width, height)); 

is more like...

shapesdraw.add(new shapewrapper(color.black, new rectangle(xpos, ypos, width, height))); 

the same goes ...triangle methods. need wrap resulting polygon in shapewrapper before trying add list