Single intent to let user take picture OR pick image from gallery in Android

You can try doing something like this:

// ...
// Within your enclosing Class
// ...
private static final int SELECT_PICTURE = 1;

// ... 

Intent pickIntent = new Intent();
pickIntent.setType("image/*");
pickIntent.setAction(Intent.ACTION_GET_CONTENT);

Intent takePhotoIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

String pickTitle = "Select or take a new Picture"; // Or get from strings.xml
Intent chooserIntent = Intent.createChooser(pickIntent, pickTitle);
chooserIntent.putExtra
(
  Intent.EXTRA_INITIAL_INTENTS, 
  new Intent[] { takePhotoIntent }
);

startActivityForResult(chooserIntent, SELECT_PICTURE);

To see how to handle the activitiy’s result, please refer to this question

Note: a critical point is how to determine whether the camera or gallery was used. That is shown in this code example: https://stackoverflow.com/a/12347567/294884