Question

On a website, one can use a social sharing javascript library like addthis in order to propose share buttons to the user without having to program everything from scratch.

Do you know any library doing the same sort of thing directly inside an android application ?

Answer 1

On Android we have Intents for this.
If you like to give the user an opportunity to share something, you can fire up an intent like this for example:

Intent share = new Intent(Intent.ACTION_SEND);
share.setType("image/jpeg") // might be text, sound, whatever
share.putExtra(Intent.EXTRA_STREAM, pathToPicture);
startActivity(Intent.createChooser(share, "share"));