Android Room Unsure what to do with methods return type

Question

I'm following Android Developers documentation and from this I have the following in my DAO:

@Insert(onConflictStrategy = OnConflictStrategy.REPLACE)
ListenableFuture<Integer> insertProjects(Project... projects);

When I was using type void I'm able to intialise the database properly and use the method as expected. However, when I use ListenableFuture, and run it, build comes out with the following error:

Not sure how to handle insert method's return type.

ListenableFuture<Integer> insertProjects(Project... projects);
                          ^

The docs don't actually tell me how to use this let alone say that an error would ensue upon it's usage.

EDIT:

The docs say this:

// Returns the number of users inserted.
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    public ListenableFuture<Integer> insertUsers(List<User> users);

What is happening and how can I fix this?

Cheers

Answer 1

As said in the documentation:

If the @Insert method receives a single parameter, it can return a long value, which is the new rowId for the inserted item. If the parameter is an array or a collection, then the method should return an array or a collection of long values instead

So try this instead:

@Insert(onConflict = OnConflictStrategy.REPLACE)
ListenableFuture<List<Long>> insertProjects(Project... projects);