Why onDraw is not called after invalidate()?

Borrowing from the link @

Android Custom Layout - onDraw() never gets called

Try the below it works

1.If you're extending a ViewGroup (in your case a RelativeLayout) you should override dispatchDraw() instead of onDraw().

Discussion on the topic @

https://groups.google.com/forum/?fromgroups=#!topic/android-developers/oLccWfszuUo

protected void dispatchDraw (Canvas canvas)

Called by draw to draw the child views. This may be overridden by derived classes to gain control just before its children are drawn (but after its own view has been drawn).

Parameters

canvas the canvas on which to draw the view

Example

public class Hello  extends Activity {

    private MyView myView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

                super.onCreate(savedInstanceState);
                Log.e("hello", "hello");
                this.myView = new MyView(this);
                setContentView(this.myView);

    }
     public class MyView extends RelativeLayout
       {

      private Paint myPaint = new Paint();
      private int[] numbers;
      public MyView(Context paramContext)
      {
        super(paramContext);
        Log.e("MyView", "MyView");
        setFocusable(true);
        setBackgroundResource(R.drawable.ic_launcher);
      }
      @Override
      protected void dispatchDraw(Canvas canvas){         

            super.dispatchDraw(canvas);     
            Log.i("...............","drawing");   
        }

  }
}

2.If you Override onDraw in the constructor call setWillNotDraw(false) then it should work.

http://developer.android.com/reference/android/view/View.html#setWillNotDraw(boolean)

public MyView(Context context) {
super(context);
sContext = context;
init();
setWillNotDraw(false); 
}

By default all ViewGroup sub-classes do not call their onDraw method, you should enable it by calling setWillNotDraw(false) link