java - 无法等待 Looper 线程内的更改

Question

这是我第一次使用 Realm。当我在模拟器上启动它时，我的应用程序停止了。日志说:

Cannot wait for changes inside a Looper thread. Use RealmChangeListeners instead.

欢迎任何帮助。

* 日志:

06-19 19:58:44.050 2464-2464/com.twitter.i_droidi.notah E/AndroidRuntime: FATAL EXCEPTION: main
                                                                          Process: com.twitter.i_droidi.notah, PID: 2464
                                                                          java.lang.RuntimeException: Unable to start activity ComponentInfo{com.twitter.i_droidi.notah/com.twitter.i_droidi.notah.MainActivity}: java.lang.IllegalStateException: Cannot wait for changes inside a Looper thread. Use RealmChangeListeners instead.
                                                                              at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
                                                                              at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
                                                                              at android.app.ActivityThread.-wrap11(ActivityThread.java)
                                                                              at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
                                                                              at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                              at android.os.Looper.loop(Looper.java:148)
                                                                              at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                              at java.lang.reflect.Method.invoke(Native Method)
                                                                              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
                                                                           Caused by: java.lang.IllegalStateException: Cannot wait for changes inside a Looper thread. Use RealmChangeListeners instead.
                                                                              at io.realm.BaseRealm.waitForChange(BaseRealm.java:274)
                                                                              at io.realm.Realm.waitForChange(Realm.java:121)
                                                                              at com.twitter.i_droidi.notah.RealmController.refresh(RealmController.java:61)
                                                                              at com.twitter.i_droidi.notah.MainActivity.onCreate(MainActivity.java:54)
                                                                              at android.app.Activity.performCreate(Activity.java:6237)
                                                                              at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
                                                                              at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
                                                                              at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
                                                                              at android.app.ActivityThread.-wrap11(ActivityThread.java) 
                                                                              at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
                                                                              at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                              at android.os.Looper.loop(Looper.java:148) 
                                                                              at android.app.ActivityThread.main(ActivityThread.java:5417) 
                                                                              at java.lang.reflect.Method.invoke(Native Method) 
                                                                              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
                                                                              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

* MainActivity.java:

import android.content.DialogInterface;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.view.LayoutInflater;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.EditText;
import android.widget.Toast;
import java.util.ArrayList;
import io.realm.Realm;
import io.realm.RealmResults;

public class MainActivity extends AppCompatActivity {

    private NotesAdapter adapter;
    private Realm realm;
    private LayoutInflater inflater;
    private RecyclerView recyclerView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        recyclerView = (RecyclerView) findViewById(R.id.recycler_view);

        this.realm = RealmController.with(this).getRealm();

        setupRecycler();

        setRealmData();

        RealmController.with(this).refresh();

        setRealmAdapter(RealmController.with(this).getNotes());

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                inflater = MainActivity.this.getLayoutInflater();

                View content = inflater.inflate(R.layout.edit_item, null);

                final EditText editTitle = (EditText) content.findViewById(R.id.edit_title);
                final EditText editBody = (EditText) content.findViewById(R.id.edit_body);

                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setView(content)
                        .setTitle("Add Note")
                        .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {

                                Notes note = new Notes();
                                note.setId(RealmController.getInstance().getNotes().size() + (int) System.currentTimeMillis());
                                note.setTitle(editTitle.getText().toString());
                                note.setBody(editBody.getText().toString());

                                if(editTitle.getText() == null || editTitle.getText().toString().equals("") || editTitle.getText().toString().equals(" "))
                                {
                                    Toast warning = Toast.makeText(MainActivity.this, "Enter a valid title!", Toast.LENGTH_SHORT);
                                    warning.show();
                                }
                                else
                                {
                                    realm.beginTransaction();
                                    realm.copyToRealm(note);
                                    realm.commitTransaction();

                                    adapter.notifyDataSetChanged();

                                    recyclerView.scrollToPosition(RealmController.getInstance().getNotes().size() - 1);
                                }
                            }
                        })
                        .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {

                                dialog.dismiss();

                            }
                        });

                AlertDialog dialog = builder.create();
                dialog.show();
            }
        });
    }

    public void setRealmAdapter(RealmResults<Notes> notes)
    {
        RealmNotesAdapter realmNotesAdapter = new RealmNotesAdapter(this.getApplicationContext(), notes);
        adapter.setRealmAdapter(realmNotesAdapter);
        adapter.notifyDataSetChanged();
    }

    private void setupRecycler()
    {
        recyclerView.setHasFixedSize(true);

        final LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        recyclerView.setLayoutManager(linearLayoutManager);

        adapter = new NotesAdapter(this);
        recyclerView.setAdapter(adapter);
    }

    private void setRealmData()
    {
        ArrayList<Notes> notes = new ArrayList<>();
        Notes note = new Notes();

        note.setId(1);
        note.setTitle("Test #1");
        note.setBody("This is Test #1.");

        note.setId(2);
        note.setTitle("Test #2");
        note.setBody("This is Test #2.");

        note.setId(3);
        note.setTitle("Test #3");
        note.setBody("This is Test #3.");

        for(Notes n : notes)
        {
            realm.beginTransaction();
            realm.copyToRealm(n);
            realm.commitTransaction();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

* RealmController.java:

import android.app.Activity;
import android.app.Application;
import android.app.Fragment;
import io.realm.Realm;
import io.realm.RealmResults;

public class RealmController {

    protected static RealmController instance;
    protected final Realm realm;

    public RealmController(Application application)
    {
        realm = Realm.getDefaultInstance();
    }

    public static RealmController with(Fragment fragment)
    {
        if(instance == null)
        {
            instance = new RealmController(fragment.getActivity().getApplication());
        }

        return instance;
    }

    public static RealmController with(Activity activity)
    {
        if(instance == null)
        {
            instance = new RealmController(activity.getApplication());
        }

        return instance;
    }

    public static RealmController with(Application application)
    {
        if(instance == null)
        {
            instance = new RealmController(application);
        }

        return instance;
    }

    public static RealmController getInstance()
    {
        return instance;
    }

    public Realm getRealm()
    {
        return realm;
    }

    public void refresh()
    {
        realm.waitForChange();
    }

    public void clearAll()
    {
        realm.beginTransaction();
        RealmResults<Notes> results = realm.where(Notes.class).findAll();
        results.deleteAllFromRealm();
        realm.commitTransaction();
    }

    public RealmResults<Notes> getNotes()
    {
        return realm.where(Notes.class).findAll();
    }

    public Notes getNote(int id)
    {
        return realm.where(Notes.class).equalTo("id", id).findFirst();
    }

    public boolean hasNotes()
    {
        return !realm.where(Notes.class).findAll().isEmpty();
    }
}

Answer 1

这只是阅读的问题。错误日志和 API 文档。:

日志

Cannot wait for changes inside a Looper thread. Use RealmChangeListeners instead.

这意味着从 onCreate 中删除 RealmController.with(this).refresh(); 行。可能的解决方法是使用 onStart/onStop 添加/删除更改监听器。

api 文档:https://realm.io/docs/java/1.0.1/api/

Realm instances on threads without a Looper cannot receive updates unless waitForChange() is manually called (...) Blocks the current thread until new changes to the Realm are available (...) Throws: java.lang.IllegalStateException - if calling this from a Looper thread

这意味着你不能从任何 Looper 线程(包括 UI 线程)调用它