来自错误线程的领域访问 Android

Question

我正在 Android 处理这个问题：

来自错误线程的领域访问。领域对象只能在创建它们的线程上访问。

我想在我的 RemoteViewsFactory 中使用 Realm

public class RemoteViewsX implements RemoteViewsFactory {

    public RemoteViews getViewAt(int paramInt) {
    if (this.results != null && this.results.size() != 0 && this.results.get(paramInt) != null) {
    //FAILED HERE
    }

}

... 本次调用失败！为什么？

我在 class:

中这样获取数据

public void onDataSetChanged() {
        Realm realm = Realm.getInstance(RemoteViewsX.this.ctx);
        this.results =  realm.where(Model.class).findAll();
}

我这样调用我的 remoteFactory :

public class ScrollWidgetService extends RemoteViewsService {
    @Override
    public RemoteViewsFactory onGetViewFactory(Intent intent) {
        return new RemoteViewsX (getApplicationContext());
    }
}

有什么想法吗？

Answer 1

如果问题是由从另一个线程调用 onDataSetChanged 和 getViewAt 引起的，您可以强制它们使用相同的线程，创建您自己的 HandlerThread，如下所示：

public class Lock {
    private boolean isLocked;

    public synchronized void lock() throws InterruptedException {
        isLocked = true;
        while (isLocked) {
            wait();
        }
    }

    public synchronized void unlock() {
        isLocked = false;
        notify();
    }
}

public class MyHandlerThread extends HandlerThread {
    private Handler mHandler;

    public MyHandlerThread() {
        super("MY_HANDLER_THREAD");
        start();
        mHandler = new Handler(getLooper());
    }

    public Handler getHandler() {
        return mHandler;
    }
}

public class RemoteViewsX implements RemoteViewsFactory {
    private MyHandlerThread mHandlerThread;
    ...
}

public void onDataSetChanged() {
    Lock lock = new Lock();
    mHandlerThread.getHandler().post(new Runnable() {
        @Override
        public void run() {
            Realm realm = Realm.getInstance(ctx);
            results = realm.where(Model.class).findAll();
            lock.unlock();
        }
    });
    lock.lock();
}

public RemoteViews getViewAt(int paramInt) {
    Lock lock = new Lock();
    final RemoteViews[] result = {null};
    mHandlerThread.getHandler().post(new Runnable() {
        @Override
        public void run() {
            // You can safely access results here.
            result[0] = new RemoteViews();
            lock.unlock();
        }
    });
    lock.lock();
    return result[0];
}

我从这个页面复制了Lockclass：http://tutorials.jenkov.com/java-concurrency/locks.html
完成任务后，不要忘记 quit 处理程序线程。

Answer 2

我是基于RxJava的，所以我是在realm里面做的。我克隆了每个项目，因为它们是主线程的一部分，当我在另一个线程（如小部件主屏幕）中工作时，这会搞砸。

myRealm.where( Dog.class ).findAllAsync().subscribe( mainThreadDogs->{
       thisThreadDogs.clear();

       for( Dog dog: mainThreadDogs ){
            thisThreadDogs.add( ModelUtil.cloneDog( dog ) ); 
       }    
});

来自错误线程的领域访问 Android

Realm access from incorrect thread Android

java

multithreading

android

realm