Can someone tell why my code for creating imagebutton is not working and provide a reference for such issues

public class SampleActivity extends AppCompatActivity {

@Override

public void onCreate(Bundle savedInstanceState)

{
    super.onCreate(savedInstanceState);
    Keypaint view = new Keypaint(this);
    setContentView(view);
}

public class Keypaint extends View
{
    Paint p;
    protected void onDraw(Canvas canvas)
    {
        super.onDraw(canvas);
        Bitmap bit = BitmapFactory.decodeResource(getResources(),R.drawable.bg);
        //canvas.drawBitmap(bit,0,0,null);
        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
    params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
        ImageButton btn = new ImageButton(getContext());
        btn.setImageBitmap(bit);

        btn.setLayoutParams(params);
       // p=new Paint();
        //Bitmap b1=BitmapFactory.decodeResource(getResources(), R.drawable.bg);
        //canvas.drawBitmap(b1, 0, 0, null);
    }

    public Keypaint(Context context)
    {
        super(context);
    }
}

}