Android - Getting Img Uri from file in drawable

You need to change your Uri. R.drawable.img is a resource id.

Example:

Uri uri = Uri.parse("android.resource://your.package.here/drawable/img");

Change "your.package.here" with the package-name of your application.

EDIT

I don't have experience with the FacebookSdk. However, a quick Google search shows code snippets and problems that relate to your question. For example, this code snippet call's setMetaData. Example:

ShareToMessengerParams shareToMessengerParams = ShareToMessengerParams.newBuilder(uri,"image/jpeg").setMetaData("{ \"image\" : \"img\" }").build();

Some more related links:

Facebook Messenger sending metadata (Android)

Get the URI of an image stored in drawable