Android 4.4 Lenovo A6000 black screen

public class HoriziontalScrollActivity extends Activity {
	TextView txtV;
	Context cntx;
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        txtV = (TextView)findViewById(R.id.idLabel);
        cntx = this;
        StringBuilder strBuild = new StringBuilder();

        // enter your date of birth
        Calendar dateOfYourBirth = new GregorianCalendar(1998, Calendar.SEPTEMBER, 17);
        Calendar today = Calendar.getInstance();
        int yourAge = today.get(Calendar.YEAR) - dateOfYourBirth.get(Calendar.YEAR);
        dateOfYourBirth.add(Calendar.YEAR, yourAge);
        if (today.before(dateOfYourBirth)) {
            yourAge--;
        }  
        strBuild.append("You are " + yourAge + " old!");
         txtV.setText(strBuild);
    }
}

 <TextView
        android:id="@+id/first_element_id"
        .........
 />
    <TextView
        android:id="@+id/second_element_id"
        android:layout_below="@id/first_element_id"
        ..........
 />

public class ApokusActivity extends Activity {
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(new SampleView(this));
	}

	private static class SampleView extends View {

		// CONSTRUCTOR
		public SampleView(Context context) {
			super(context);
			setFocusable(true);

		}
		@Override
		protected void onDraw(Canvas canvas) {
			Paint paint = new Paint();
			
			canvas.drawColor(Color.GREEN);
            
           Bitmap b = Bitmap.createBitmap(200, 200, Bitmap.Config.ALPHA_8);
           Canvas c = new Canvas(b);
           c.drawRect(0, 0, 200, 200, paint);
           
           paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
           paint.setTextSize(40);
           paint.setTextScaleX(1.f);
           paint.setAlpha(0);
           paint.setAntiAlias(true);
           c.drawText("Your text", 30, 40, paint);
           paint.setColor(Color.RED);
           
           canvas.drawBitmap(b, 10,10, paint);
		}

	}
}

               
<Button
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:gravity="left|center_vertical"
                    android:paddingLeft="20dp"
                    android:text="My Button"
                     />

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(new SampleView(this));
	}

	private static class SampleView extends View {

		// CONSTRUCTOR
		public SampleView(Context context) {
			super(context);
			setFocusable(true);

		}

		@Override
		protected void onDraw(Canvas canvas) {
			Paint paint = new Paint();

			canvas.drawColor(Color.YELLOW);

			 Bitmap b = Bitmap.createBitmap(200, 200,
			 Bitmap.Config.ARGB_8888);

			// you need to insert a image flower_blue into res/drawable folder

			paint.setFilterBitmap(true);
			Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(),
					R.drawable.flower_blue);
			canvas.drawBitmap(bitmapOrg, 10, 10, paint);
			int width, height;

		    Canvas c = new Canvas(b);
		    paint.setAlpha(255); //0x80
		    c.translate(0, 30);
		    c.drawBitmap(bitmapOrg, new Matrix(), paint);
		    paint.setColor(Color.BLUE);
        Path mPath = new Path();
		    mPath.addCircle(50, 50, 50, Path.Direction.CCW);
            //c.clipPath(mPath, Region.Op.UNION);
            //c.clipPath(mPath, Region.Op.DIFFERENCE);
            c.clipPath(mPath, Region.Op.INTERSECT);
            //c.clipPath(mPath, Region.Op.REPLACE);
            //c.clipPath(mPath, Region.Op.XOR);
           paint.setColor(Color.GREEN);
           paint.setAntiAlias(true);
           c.drawCircle(30, 20, 30, paint);

		    int h = bitmapOrg.getHeight();
			//canvas.drawBitmap(bitmapOrg, 10, 10, paint);
			canvas.drawBitmap(b, 0, 10 + h + 10, paint);

		}

	}
}