How to save exff data to image?

private File getOutputPhotoFile() throws IOException {
		  File directory = new File(Environment.getExternalStoragePublicDirectory(
		                Environment.DIRECTORY_PICTURES), getPackageName());
		  if (!directory.exists()) {
		    if (!directory.mkdirs()) {
		      Log.e(TAG, "Failed to create storage directory.");
		      return null;
		    }
		  }
		  
		  
		  String timeStamp = new SimpleDateFormat("yyyMMdd_HHmmss", Locale.ENGLISH).format(new Date());
		 
		  File[] files = directory.listFiles();
 
		  File exifVar =  new File(directory.getPath(), "IMG_" + timeStamp + ".jpg");
		  if(files.length!=0) {
		      File newestFile = files[files.length-1];
		      exifVar =  new File(directory.getPath() + File.separator + newestFile.getName());
		  }
		  
		  String mString = "Generic Text..";     
		  ExifInterface exif = new ExifInterface(exifVar.getAbsolutePath());
		  exif.setAttribute("UserComment", mString);
		  exif.saveAttributes();
		 
		    
		  exif.setAttribute(ExifInterface.TAG_GPS_LATITUDE,
	        String.valueOf(latituteField.toString()));
 
		  exif.setAttribute(ExifInterface.TAG_GPS_LONGITUDE, 
	        String.valueOf(longitudeField.toString()));
 
		  exif.saveAttributes();
		 
		  return exifVar; 
		  
		  
		  
		  
	}