canvas - Android drawBitmap paint -

i trying show bullets when user touched screen

i making bullet here

public projectile(context context, attributeset attrs, int defstyle) {         super(context, attrs, defstyle);         paint = new paint();         bulletbitmap = bitmapfactory.decoderesource(context.getresources(),                                                     r.drawable.bullet);     }      public interface projectilelistener {         public void onprojectilechanged(float delta, float angle);     }      public void setprojectilelistener(projectilelistener l) {         listener = l;     }      public void setprojectiledirection(int x, int y, int size){         pos = new rect(x, y, size, size);         invalidate();     }      protected void ondraw(canvas c) {         c.drawbitmap(bulletbitmap, pos, pos, paint);         super.ondraw(c);     } 

and call here

projectile p = new projectile(toweranimation.this);                         p.setprojectiledirection(x, y, 50);                         projectiles.add(p);                         canvas c = null;                         p.ondraw(c); 

however getting errors on line

c.drawbitmap(bulletbitmap, pos, pos, paint); 

did make wrong drawbitmap? thanks

in following code:

projectile p = new projectile(toweranimation.this);                     p.setprojectiledirection(x, y, 50);                     projectiles.add(p);                     canvas c = null;    <------------------ here                     p.ondraw(c);        <------------------ npe 

you setting c null , passing ondraw(). what's happening in ondraw():

protected void ondraw(canvas c) {     null.drawbitmap(bulletbitmap, pos, pos, paint);    <--------- npe     super.ondraw(c); } 

edit 1:

i'm not sure trying code. check class bulletsonscreen. use it, need add view layout. example, if have linearlayout, can use addview() method:

mylinearlayout.addview(new bulletsonscreen(this));  public class bulletsonscreen extends view {      bitmap bullet;      boolean touched;      float xvalue, yvalue;      public bulletsonscreen(context context) {          super(context);          setfocusable(true);          bullet = bitmapfactory.decoderesource(context.getresources(),                                                 r.drawable.bullet);          touched = false;      }      protected void ondraw(canvas canvas) {          if (touched) {              canvas.drawbitmap(bullet, xvalue,              yvalue, null);              touched = false;          }     }      public boolean ontouchevent(motionevent event) {      xvalue = event.getx();     yvalue = event.gety();              touched = true;             invalidate();     }