Android - 领域 - 对象删除 - 对象不再有效操作答案

【问题标题】：Android - Realm - Object delete - Object is no longer valid to operate onAndroid - 领域 - 对象删除 - 对象不再有效操作
【发布时间】：2016-07-28 09:08:48
【问题描述】：

我正在尝试从由 Realm 数据库填充的 RecyclerView 中删除一个项目，我收到以下错误：

java.lang.IllegalStateException: Illegal State: 
Object is no longer valid to operate on. Was it deleted by another thread?

假设我想我是在它已经被删除时尝试访问，但我不明白在哪里。

背景： 我正在显示一个城市列表，长按某个项目会显示一个对话框，要求确认删除。

该项目已在数据库中删除，因为当我重新启动应用程序时，它不再存在。

领域到数组列表

public static ArrayList<City> getStoredCities(){
        RealmQuery<City> query = getRealmInstance().where(City.class);
        final RealmResults<City>results =
                realm.where(City.class)
                        .findAllSorted("timestamp", Sort.DESCENDING);

        results.size();

        ArrayList<City> cityArrayList = new ArrayList<>();

        for(int i = 0; i< results.size(); i++){
            cityArrayList.add(results.get(i));
        }

        return cityArrayList;
    }

对话框代码

builder.setPositiveButton(getString(R.string.ok), new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialogInterface, int i) {
        RealmHelper.removeCity(cityArrayList.get(position));
        cityArrayList.remove(position);
        mRecyclerView.removeViewAt(position);
        mCityListAdapter.notifyItemRemoved(position);
        mCityListAdapter.notifyItemRangeChanged(position, cityArrayList.size());
        mCityListAdapter.notifyDataSetChanged();
    }
});

Realm方法删除项目

public static void removeCity(City city){
        RealmResults<City> result = realm.where(City.class).equalTo("cityName", city.getCityName()).findAll();
        realm.beginTransaction();
        result.deleteAllFromRealm();
        realm.commitTransaction();
}

日志

07-28 11:02:08.461 9461-9461/com.ilepez.weatherapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.ilepez.weatherapp, PID: 9461
java.lang.IllegalStateException: Illegal State: 
Object is no longer valid to operate on. Was it deleted by another thread?
at io.realm.internal.UncheckedRow.nativeGetString(Native Method)
at io.realm.internal.UncheckedRow.getString(UncheckedRow.java:153)
at io.realm.CityRealmProxy.realmGet$cityName(CityRealmProxy.java:75)
at com.ilepez.weatherapp.data.model.City.getCityName(City.java:41)
at com.ilepez.weatherapp.adapter.CityListAdapter.onBindViewHolder(CityListAdapter.java:56)
at com.ilepez.weatherapp.adapter.CityListAdapter.onBindViewHolder(CityListAdapter.java:20)
at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:5768)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:5801)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5037)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4913)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2029)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1414)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1377)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:588)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3260)
at android.support.v7.widget.RecyclerView.onMeasure(RecyclerView.java:2788)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.support.design.widget.NavigationView.onMeasure(NavigationView.java:218)
at android.view.View.measure(View.java:20151)
at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:1108)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:747)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:747)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:3158)
at android.view.View.measure(View.java:20151)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2594)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1549)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1841)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1437)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7403)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:920)
at android.view.Choreographer.doCallbacks(Choreographer.java:695)
at android.view.Choreographer.doFrame(Choreographer.java:631)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:906)
at android.os.Handler.handleCall

适配器代码

public class CityListAdapter extends RecyclerView.Adapter<CityListAdapter.CityListViewholder>{

public interface OnItemClickListener{
    void onItemClick(int position);
}

public interface OnItemLongClickListener{
    void onItemLongClick(int position);
}

private static final String LOG_TAG = CityListAdapter.class.getSimpleName();

private ArrayList<City> cityArrayList = new ArrayList<>();
private Context mContext;
private OnItemClickListener onItemClickListener;
private OnItemLongClickListener onItemLongClickListener;

public CityListAdapter(Context context, ArrayList<City> cityArrayList, OnItemClickListener onItemClickListener, OnItemLongClickListener onItemLongClickListener) {
    this.cityArrayList = cityArrayList;
    this.mContext = context;
    this.onItemClickListener = onItemClickListener;
    this.onItemLongClickListener = onItemLongClickListener;
}

@Override
public CityListViewholder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.city_item_navigation_viewholder, null);
    CityListViewholder cityListViewholder = new CityListViewholder(view, parent.getContext());
    return cityListViewholder;
}

@Override
public void onBindViewHolder(CityListViewholder holder, int position) {
    holder.cityName.setText(cityArrayList.get(position).getCityName());
    holder.bindClick(position, onItemClickListener);
    holder.bindLongClick(position, onItemLongClickListener);
}

@Override
public int getItemCount() {
    return cityArrayList.size();
}


public class CityListViewholder extends RecyclerView.ViewHolder{

    TextView cityName;
    ImageView cityIcon;

    public CityListViewholder(View itemView, Context context) {
        super(itemView);
        cityName = (TextView)itemView.findViewById(R.id.city_name);
        cityIcon = (ImageView)itemView.findViewById(R.id.city_icon);
    }

    public void bindClick(final int position, final OnItemClickListener onItemClickListener){
        itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                onItemClickListener.onItemClick(position);
            }
        });
    }

    public void bindLongClick(final int position, final OnItemLongClickListener onItemLongClickListener) {
        itemView.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View view) {
                onItemLongClickListener.onItemLongClick(position);
                return true;
            }
        });
    }
}
}

【问题讨论】：

这个错误在哪里抛出？在适配器中？是普通的 RecyclerView，还是 RealmRecyclerView？
它指向一个领域文件：CityRealmProxy，这使应用程序崩溃 @SuppressWarnings("cast") public String realmGet$cityName() { proxyState.getRealm$realm().checkIfValid(); return (java.lang.String) proxyState.getRow$realm().getString(columnInfo.cityNameIndex); }
logcat 中的某处它应该告诉您您自己的代码的哪一行触发了此错误。你可以复制到这里
为了更好的可读性，我更新了我的问题并添加了日志，感谢您的帮助。
也添加了适配器代码

标签： android realm

【解决方案1】：

好的，所以你调用adapter.notifyDataSetChanged()，所以任何其他notify___ 方法都是不必要的（数据集更改无论如何都会禁用动画。）

在这种情况下，最简单（也是最有效）的处理方式是直接使用 RealmResults，而不是将每个元素检索到 ArrayList 中，然后以完全相同的方式使用。

所以应该是这样的

public static RealmResults<City> getStoredCities(){
        RealmQuery<City> query = getRealmInstance().where(City.class);
        return realm.where(City.class)
                        .findAllSorted("timestamp", Sort.DESCENDING);
}

和

public static void removeCity(City city){
        final String cityName = city.getCityName();
        realm.executeTransaction(new Realm.Transaction() {
            @Override
            public void execute(Realm realm) {
                RealmResults<City> result = realm.where(City.class).equalTo("cityName", cityName).findAll();
                result.deleteAllFromRealm();
            }
        });
}

和

builder.setPositiveButton(getString(R.string.ok), new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialogInterface, int i) {
        RealmHelper.removeCity(getItem(position));
    }
});

和

// dependency: compile 'io.realm:android-adapters:1.3.0' 
// <-- for Realm 3.x+, use 2.0.0
// for Realm 5.x+, use 3.0.0
public class CityListAdapter extends RealmRecyclerViewAdapter<City, CityListViewHolder> { 

    OnItemClickListener onItemClickListener;
    OnItemLongClickListener onItemLongClickListener;

    public CityListAdapter(@NonNull Context context, 
                           @Nullable OrderedRealmCollection<City> data, 
                           OnItemClickListener onItemClickListener, 
                           OnItemLongClickListener onItemLongClickListener) {
        super(context, data, true);
        this.onItemClickListener = onItemClickListener;
        this.onItemLongClickListener = onItemLongClickListener;
    }


    @Override
    public CityListViewholder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.city_item_navigation_viewholder, parent, false);
        CityListViewholder cityListViewholder = new CityListViewholder(view, parent.getContext());
        return cityListViewholder;
    }

    @Override
    public void onBindViewHolder(CityListViewholder holder, int position) {
        holder.cityName.setText(getItem(position).getCityName());
        holder.bindClick(position, onItemClickListener);
        holder.bindLongClick(position, onItemLongClickListener);
    }

    public static class CityListViewholder extends RecyclerView.ViewHolder {
        TextView cityName;
        ImageView cityIcon;

        public CityListViewholder(View itemView, 
                                  Context context) {
            super(itemView);
            cityName = (TextView)itemView.findViewById(R.id.city_name);
            cityIcon = (ImageView)itemView.findViewById(R.id.city_icon);
        }

        public void bindClick(final int position, final OnItemClickListener onItemClickListener){
            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    onItemClickListener.onItemClick(position);
                }
            });
        }

        public void bindLongClick(final int position, final OnItemLongClickListener onItemLongClickListener) {
            itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View view) {
                    onItemLongClickListener.onItemLongClick(position);
                    return true;
                }
            });
        }
    }
}

只要您的结果发生变化，使用RealmRecyclerViewAdapter 就会调用notifyDataSetChanged()。

【讨论】：

我目前正在实施:) - 在 remove 方法中，getdata() 似乎无法识别RealmHelper.removeCity(getData().get(position));
getItem(position) 如果我知道正确的话也可以工作，尽管getData() 对我有用
尽管您可能指的是对话框构建器代码。那必须是results.get(position)，但我不确定你在哪里使用代码。
我只能返回代码，再次感谢您的帮助。 getData 对我不起作用，使用 RealmHelper.getStoredCities().get(position) 有意义吗？
getData()是RealmRecyclerViewAdapter的方法