realm findFirstAsync

MainActivity.java

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import com.oldroid.examples.realm.models.Conversation;
import io.realm.Realm;
import rx.subscriptions.CompositeSubscription;

public class MainActivity extends AppCompatActivity {
  private static final String TAG = MainActivity.class.getSimpleName();

  private CompositeSubscription subscription = new CompositeSubscription();
  private Realm realm;

  @Override protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    realm = Realm.getInstance(this);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    subscription.add(realm.where(Conversation.class)
        .findFirstAsync()
        .<Conversation>asObservable()
        .filter(Conversation::isLoaded)
        .subscribe(conversation -> {
          if (conversation.isValid()) {
            d("Conversation=" + conversation.toString());
          } else {
            d("Conversation is null");
          }
        }));
  }

  @Override protected void onDestroy() {
    super.onDestroy();
    subscription.unsubscribe();
    realm.close();
  }

  private void d(String message) {
    Log.d(TAG, String.format("[%s] %s", Thread.currentThread().getName(), message));
  }
}