Android Room: Beyond the Codelab - 9

MainActivity.java

...
mTodosViewModel.todos.observe(this, (todos -> {
     new Thread(() -> {
         DiffUtil.DiffResult result = DiffUtil.calculateDiff(new DiffUtil.Callback() {
             ...
         });
         self.runOnUiThread(() -> {
             result.dispatchUpdatesTo(todosAdapter);
             mTodos = todos;
             mProgressDialog.hide();
         });
     }).start();
 }));
...