java - How to update a SurfaceView? -

i've extended surfaceview , managed draw in activity. activity should able call method on surfaceview changes parameter , redraws it. how can update function implemented?

this class:

public class mysurfaceview extends surfaceview                                     implements surfaceholder.callback {      private int circleradius = 50;     private surfaceholder sh;     private final paint paint = new paint(paint.anti_alias_flag);      public mysurfaceview(context context, attributeset as) {         super(context,as);         sh = getholder();         sh.addcallback(this);         paint.setcolor(color.blue);         paint.setstyle(style.fill);     }     public void surfacecreated(surfaceholder holder) {         canvas canvas = sh.lockcanvas();         canvas.drawcolor(color.black);         canvas.drawcircle(100, 200, circleradius, paint);         sh.unlockcanvasandpost(canvas);     }     public void update( newradius ) {         circleradius = newradius;         // more?     } } 

what should update contain redraw everything? have surfacechanged?

• the update function should call invalidate() or postinvalidate() in order view redraw.
• further, redrawing disabled default surfaceviews. enable calling setwillnotdraw(false) in e.g. surfacecreated.