title: Getting error while saving image from bitmap. Gives NullPointException Error
body: <p>I am trying to take photo from camera intent and add some textview on image (overlay) and then saving this mixed image. For this I am using below code.</p>
  
  <p>MAIN PROBLEM: This code working perfectly when I put it under button's on click listner. but when I put it in "onCreate" method, its showing an error "Attempt to invoke virtual method 'boolean android.graphics.Bitmap.compress(android.graphics.Bitmap$CompressFormat, int, java.io.OutputStream)' on a null object reference".</p>
  
  <p>I searched a lot for this. Tried almost every solution provided in stackvoerflow. </p>
  
  <pre><code>   private void saveImage() {
          try {
              frameLayout.setDrawingCacheEnabled(true);
              frameLayout.buildDrawingCache();
  //            drawingCache = BitmapFactory.decodeResource(getResources(), R.id.imageview);
  //            drawingCache = ((BitmapDrawable) imageView.getDrawable()).getBitmap();
              drawingCache = frameLayout.getDrawingCache();
              String timeStamp = new SimpleDateFormat("ddMMyyyy_hhmmss").format(new Date());
              saveImageFile = new File(path, "my_folder" + timeStamp + ".jpg");
              OutputStream fOut = new FileOutputStream(saveImageFile);
              tempPhoto = saveImageFile;
              drawingCache.compress(Bitmap.CompressFormat.JPEG, 100, fOut);
              fOut.flush();
              fOut.close();
              Toast.makeText(this, "Image Saved Successfully", Toast.LENGTH_SHORT).show();
              deleteTempImage(mCurrentPhotoPath);
  //            Toast.makeText(this, mCurrentPhotoPath, Toast.LENGTH_LONG).show();
          } catch (FileNotFoundException e) {
              e.printStackTrace();
          } catch (IOException e) {
              e.printStackTrace();
          }
      }
  
  </code></pre>
  
  <p>I want to perform saveImage function at onCreate method, otherwise user will force to click "save" button each time. Please help me. I spent almost 2 days for this.</p>