title: matrix.postRotate(90) in image rotation
body: <p>I can only rotate the image once and when I click on the button again, the image freeze and doesn't rotate. Please help me. </p>
  
  <pre><code>try{
      //Bitmap bMap;
  
      //Get ImageView from layout xml file
      img = (ImageView) findViewById(R.id.imageView01);
  
      //Decode Image using Bitmap factory.
      Bitmap bMap = BitmapFactory.decodeFile(selectedImagePath);
  
      //Create object of new Matrix.
      Matrix matrix = new Matrix();
  
      //set image rotation value to 90 degrees in matrix.
      matrix.postRotate(90);
  
      //Create bitmap with new values.
      Bitmap bMapRotate = Bitmap.createBitmap(bMap, 0, 0, bMap.getWidth(), bMap.getHeight(), matrix, true);
  
      //put rotated image in ImageView.
      img.setImageBitmap(bMapRotate);
  
      Context context = getApplicationContext();
      CharSequence text = "Image Rotated" ;
      int duration = Toast.LENGTH_SHORT;
  
      Toast toast = Toast.makeText(context, text, duration);
  
      toast.show();
  
  }catch (Exception e) {       
      e.printStackTrace();
      displayExceptionMessage(e.getMessage());
  }
  </code></pre>