Realm access from incorrect thread

问题:

I have an application with a LoginActivity, that when the user login correctly, I register to receive messages. And the LoginActivity jumps to MainActivity. The arriving messages are supposed to be stored in database (Realm), to recover from a Realm instance in Main.

But when the message arrives It crash realm launching this errror:

Exception in packet listener     java.lang.IllegalStateException: Realm access from incorrect thread. Realm objects can only be accessed on the thread they were created.     at io.realm.BaseRealm.checkIfValid(BaseRealm.java:383)     at io.realm.Realm.executeTransactionAsync(Realm.java:1324)     at io.realm.Realm.executeTransactionAsync(Realm.java:1276)     at es.in2.in2tant.LoginActivity.newMessageReceived(LoginActivity.java:124)     at es.in2.in2tant.Connection.Connection$4$1.processMessage(Connection.java:227)     at org.jivesoftware.smack.chat.Chat.deliver(Chat.java:180)     at org.jivesoftware.smack.chat.ChatManager.deliverMessage(ChatManager.java:351)     at org.jivesoftware.smack.chat.ChatManager.access$300(ChatManager.java:53)     at org.jivesoftware.smack.chat.ChatManager$2.processPacket(ChatManager.java:162)     at org.jivesoftware.smack.AbstractXMPPConnection$4.run(AbstractXMPPConnection.java:1126)     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)     at java.lang.Thread.run(Thread.java:818) 

I'm a bit lost on how Realm works, and I don't know how to make realm accessible across the application without a crash and keep storing this received messages from LoginActivity. Some help, or approaches to achieving this?

LoginActivity.java:

public class LoginActivity extends AppCompatActivity implements ConnectionConnectResponse { ..... protected void onCreate(Bundle savedInstanceState) { //Realm Init config:         Realm.init(this);         RealmConfiguration realmConfiguration = new RealmConfiguration.Builder().build();         Realm.deleteRealm(realmConfiguration); // Clean slate         Realm.setDefaultConfiguration(realmConfiguration); // Make this Realm the default   @Override     public void newMessageReceived(final ChatMessage message) {         Logger.d("NEWMESSAGERECEIVED :" + message);           realm.executeTransactionAsync(new Realm.Transaction() {             @Override             public void execute(Realm realm) {                  Message receivedMessage = realm.createObject(Message.class, message.id);                 receivedMessage.setBodyMessage(message.message);                 receivedMessage.setFrom(message.from);                 receivedMessage.setTo(message.to);                 receivedMessage.setDelivered(false);                 receivedMessage.setMine(false);                 receivedMessage.setDate(Calendar.getInstance().getTime());             }         });         //Logger.d("NEWMESSRE: LAST MESSAGE:" + realm.where(Message.class).equalTo("chatID", message.id));     }  @Override     protected void onStart() {         super.onStart();         realm = Realm.getDefaultInstance();     }      @Override     protected void onStop() {         super.onStop();         realm.close();     } 

Image of what is needed:

回答1:

Realm access from incorrect thread. Realm objects can only be accessed on the thread they were created.

This error message is quite self-explanatory.

As i see you're initializing realm by calling Realm.getDefaultInstance() on the UI thread.

The error is coming from newMessageReceived(), so i guess that method is called from a background thread.

Either obtain a Realm instance on the background thread and use that instead of the global instance:

@Override public void run () {     Realm backgroundRealm = Realm.getDefaultInstance();     backgroundRealm.executeTransactionAsync(new Realm.Transaction() {         @Override         public void execute(Realm realm) {             Message receivedMessage = realm.createObject(Message.class, message.id);             receivedMessage.setBodyMessage(message.message);             receivedMessage.setFrom(message.from);             receivedMessage.setTo(message.to);             receivedMessage.setDelivered(false);             receivedMessage.setMine(false);             receivedMessage.setDate(Calendar.getInstance().getTime());         }     }); } 

Or, if you would like to stick to the global Realm instance for some reason, then make sure your code is executed on the UI thread by calling runOnUiThread() (or directly posting a Runnable to the message queue of the main thread through a Handler):

@Override public void newMessageReceived(final ChatMessage message) {     runOnUiThread(new Runnable() {         @Override         public void run() {             realm.executeTransactionAsync(new Realm.Transaction() {                 @Override                 public void execute(Realm realm) {                     Message receivedMessage = realm.createObject(Message.class,                         message.id);                     receivedMessage.setBodyMessage(message.message);                     receivedMessage.setFrom(message.from);                     receivedMessage.setTo(message.to);                     receivedMessage.setDelivered(false);                     receivedMessage.setMine(false);                     receivedMessage.setDate(Calendar.getInstance().getTime());                 }             });         }     }); } 

回答2:

Allocate instance before transaction and release it right after transaction is complete, so you won't have linegring connection and by doing so, you perform savings from thread scheduler. I use 'Data Access Object' interface for manipulations with data and that interface is implemented using Realm. Don't use 'transaction async', use all calls synchronously, but perform calls on 'data access object' from background thread. Good solution for that - rxJava library. Just get and release Realm instance all the time - library makes it inexpensive.

回答3:

I haven't use Realm yet. But what i understood from the error message is that ConnectionConnectResponse may be alive when Loginactivity die. So you should pass Realm instance as a parameter inside

newMessageReceived(Realm realm, final ChatMessage message)

and put all the Realm init code in the class where you fire this method.

文章来源: Realm access from incorrect thread