How to write text through Canvas in android?

public class CanvasGreetingActivity extends Activity {

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

 private static class SampleView extends View {
   public SampleView(Context context) {
     super(context);
     setDrawingCacheEnabled(true);
   }

   @Override
   protected void onDraw(Canvas canvas) {
     canvas.drawColor(Color.WHITE);

     String blackText = "black";
     String redText = " red";

     Paint mPaint = new Paint();
     mPaint.setAntiAlias(true);
     mPaint.setTextSize(30);
     mPaint.setTypeface(Typeface.create(Typeface.SERIF,Typeface.ITALIC));

     float canvasWidth = canvas.getWidth();
     float blackTextWidth = mPaint.measureText(blackText);
     float sentenceWidth = mPaint.measureText(blackText + redText);
     float startPositionX = (canvasWidth - sentenceWidth) / 2;

     mPaint.setTextAlign(Paint.Align.LEFT);
     canvas.translate(0, 80);

     mPaint.setColor(Color.BLACK);
     canvas.drawText(blackText, startPositionX, 0, mPaint);
     mPaint.setColor(Color.RED);
     canvas.drawText(redText, startPositionX + blackTextWidth, 0,mPaint);
   }
 }