Restoring Room database from a local backup file, LiveData ViewModel doesn't refresh

问题

I'm trying to restore a room database programmatically.

I followed this tutorial to implement a view model using LiveData of Words list, so that the words list refresh automatically on screan when insert, delete or update.

 mWordViewModel.getAllWords().observe(this, new Observer<List<Word>>() {
        @Override
        public void onChanged(@Nullable final List<Word> Words) {
            // Update the cached copy of the Ussds in the adapter.
            adapter.setWords(Words);
        }
    });

I also used the following code to backup and restore the database file.

But the problem is that my words list does not refresh automatically after restoring the database file. The workaround I currently use is to restart the main activity :

finish(); 
startActivity(getIntent());

How can I make the main activity refresh automatically the words list after the database file is restored,in a smarter way?

Backup/resotre db file :

if(id == R.id.action_save_db) {
    int permission = ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
    if(permission == PackageManager.PERMISSION_GRANTED) {
        AppDatabase.getInstance(this).getDatabase().close();

        File db = getDatabasePath("my-db");
        File dbShm = new File(db.getParent(), "my-db-shm");
        File dbWal = new File(db.getParent(), "my-db-wal");

        File db2 = new File("/sdcard/", "my-db");
        File dbShm2 = new File(db2.getParent(), "my-db-shm");
        File dbWal2 = new File(db2.getParent(), "my-db-wal");

        try {
            FileUtils.copyFile(db, db2);
            FileUtils.copyFile(dbShm, dbShm2);
            FileUtils.copyFile(dbWal, dbWal2);
        } catch (Exception e) {
            Log.e("SAVEDB", e.toString());
        }
    } else {
        Snackbar.make(mDrawer, "Please allow access to your storage", Snackbar.LENGTH_LONG)
                .setAction("Allow", view -> ActivityCompat.requestPermissions(this, new String[] {
                        Manifest.permission.WRITE_EXTERNAL_STORAGE
                }, 0)).show();
    }
} else if(id == R.id.action_load_db) {
    int permission = ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);
    if(permission == PackageManager.PERMISSION_GRANTED) {
        AppDatabase.getInstance(this).getDatabase().close();

        File db = new File("/sdcard/", "my-db");
        File dbShm = new File(db.getParent(), "my-db-shm");
        File dbWal = new File(db.getParent(), "my-db-wal");

        File db2 = getDatabasePath("my-db");
        File dbShm2 = new File(db2.getParent(), "my-db-shm");
        File dbWal2 = new File(db2.getParent(), "my-db-wal");

        try {
            FileUtils.copyFile(db, db2);
            FileUtils.copyFile(dbShm, dbShm2);
            FileUtils.copyFile(dbWal, dbWal2);
        } catch (Exception e) {
            Loge("RESTOREDB", e.toString());
        }
    } else {
        Snackbar.make(mDrawer, "Please allow access to your storage", Snackbar.LENGTH_LONG)
                .setAction("Allow", view -> ActivityCompat.requestPermissions(this, new String[] {
                        Manifest.permission.READ_EXTERNAL_STORAGE
                }, 0)).show();
    }
 }

来源：https://stackoverflow.com/questions/54113968/restoring-room-database-from-a-local-backup-file-livedata-viewmodel-doesnt-ref