Android RecyclerView项目删除，但当我移动到其他活动时返回，然后返回

我在我的recyclerView中添加了一些新代码，在向左或向右滑动时删除该项目，但当我移动到其他活动，然后返回到我的recyclerView活动时，这些项目会重新出现。以下是我的MainActivity（称为TestGroceryList）的代码：

公共类TestGroceryList扩展了AppCompative活动{
私有WordViewModel mWordViewModel；
公共静态最终int NEW\u WORD\u ACTIVITY\u REQUEST\u CODE=1；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity\u test\u screery\u list）；
RecyclerView RecyclerView=findViewById（R.id.RecyclerView）；
最终WordListAdapter=新WordListAdapter（此）；
recyclerView.setAdapter（适配器）；
recyclerView.setLayoutManager（新的LinearLayoutManager（本））；
mWordViewModel=newViewModelProvider（this.get）（WordViewModel.class）；
mWordViewModel.getAllWords（）.observe（这个，新的观察者（）{
@凌驾
公共void onChanged（@Nullable final List words）{
//更新适配器中单词的缓存副本。
adapter.setWords（单词）；
}
});
新建ItemTouchHelper（新建ItemTouchHelper.SimpleCallback（0，ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT）{
@凌驾
公共布尔onMove（@NonNull RecyclerView RecyclerView，@NonNull RecyclerView.ViewHolder ViewHolder，@NonNull RecyclerView.ViewHolder target）{
返回false；
}
@凌驾
公共void onsweed（@NonNull RecyclerView.ViewHolder ViewHolder，int-direction）{
delete（adapter.getWordAt（viewHolder.getAdapterPosition（））；
Toast.makeText（TestGroceryList.this，“项目已删除！”，Toast.LENGTH\u SHORT.show（）；
}
}).attachToRecyclerView（recyclerView）；
FloatingActionButton fab=findViewById（R.id.fab）；
fab.setOnClickListener（新视图.OnClickListener（）{
@凌驾
公共void onClick（视图）{
Intent Intent=newintent（TestGroceryList.this，NewWordActivity.class）；
startActivityForResult（意图、新词、活动、请求、代码）；
}
});
}
ActivityResult上的公共void（int请求代码、int结果代码、意图数据）{
super.onActivityResult（请求代码、结果代码、数据）；
if（requestCode==NEW\u WORD\u ACTIVITY\u REQUEST\u CODE&&resultCode==RESULT\u OK）{
Word=newword（data.getStringExtra（NewWordActivity.EXTRA_REPLY））；
mWordViewModel.insert（word）；
}否则{
Toast.makeText(
getApplicationContext（），
R.string.empty\u未保存，
Toast.LENGTH_LONG）.show（）；
}
}

下面是我的适配器的代码：

public class WordListAdapter extends RecyclerView.Adapter<WordListAdapter.WordViewHolder> {


    static class WordViewHolder extends RecyclerView.ViewHolder {
        private final TextView wordItemView;

        private WordViewHolder(View itemView) {
            super(itemView);
            wordItemView = itemView.findViewById(R.id.textView);
        }
    }

    private final LayoutInflater mInflater;
    private List<Word> mWords; // Cached copy of words

    WordListAdapter(Context context) { mInflater = LayoutInflater.from(context); }

    @Override
    public WordViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView = mInflater.inflate(R.layout.recycler_item, parent, false);
        return new WordViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(WordViewHolder holder, int position) {
        if (mWords != null) {
            Word current = mWords.get(position);
            holder.wordItemView.setText(current.getWord());
        } else {
            // Covers the case of data not being ready yet.
            holder.wordItemView.setText("No thecookbookerapp.com.Word");
        }
    }

    void setWords(List<Word> words){
        mWords = words;
        notifyDataSetChanged();
    }

    public Word getWordAt(int position){
        return mWords.get(position);
    }


    // getItemCount() is called many times, and when it is first called,
    // mWords has not been updated (means initially, it's null, and we can't return null).
    @Override
    public int getItemCount() {
        if (mWords != null)
            return mWords.size();
        else return 0;
    }
}

公共类WordListAdapter扩展了RecyclerView.Adapter{
静态类WordViewHolder扩展了RecyclerView.ViewHolder{
私有最终文本视图wordItemView；
私有WordViewHolder（查看项目视图）{
超级（项目视图）；
wordItemView=itemView.findViewById（R.id.textView）；
}
}
私人最终布局平面图；
私有列表mWords；//缓存的单词副本
WordListAdapter（上下文）{mInflater=LayoutInflater.from（上下文）；}
@凌驾
public WordViewHolder onCreateViewHolder（视图组父级，int-viewType）{
View itemView=mInflater.inflate（R.layout.recycler\u项目，父项，false）；
返回新的WordViewHolder（itemView）；
}
@凌驾
BindViewHolder上的公共无效（WordViewHolder，int位置）{
if（mWords！=null）{
单词current=mWords.get（位置）；
holder.wordItemView.setText（current.getWord（））；
}否则{
//涵盖数据尚未准备就绪的情况。
holder.wordItemView.setText（“No thecookbookerapp.com.Word”）；
}
}
无效设置字（列出字）{
MWORD=单词；
notifyDataSetChanged（）；
}
公共单词getWordAt（int位置）{
返回mWords.get（位置）；
}
//getItemCount（）被多次调用，第一次调用时，
//mWords尚未更新（最初表示为null，我们不能返回null）。
@凌驾
public int getItemCount（）{
if（mWords！=null）
返回mWords.size（）；
否则返回0；
}
}

以下是我的WordViewModel：

package thecookbookerapp.com;

import android.app.Application;
import android.content.Intent;
import android.widget.Toast;

import androidx.lifecycle.AndroidViewModel;
import androidx.lifecycle.LiveData;

import java.util.List;

import static android.app.Activity.RESULT_OK;
import static 
thecookbookerapp.com.TestGroceryList.NEW_WORD_ACTIVITY_REQUEST_CODE;

public class WordViewModel extends AndroidViewModel {

private WordRepository mRepository;

private LiveData<List<Word>> mAllWords;

public WordViewModel (Application application) {
    super(application);
    mRepository = new WordRepository(application);
    mAllWords = mRepository.getAllWords();
}

public static void delete(Word wordAt) {

}

LiveData<List<Word>> getAllWords() { return mAllWords; }

public void insert(Word word) { mRepository.insert(word); }

}

打包cookbookerapp.com；
导入android.app.Application；
导入android.content.Intent；
导入android.widget.Toast；
导入androidx.lifecycle.AndroidViewModel；
导入androidx.lifecycle.LiveData；
导入java.util.List；
导入静态android.app.Activity.RESULT\u确定；
导入静态
cookbookerapp.com.TestGroceryList.NEW\u WORD\u ACTIVITY\u REQUEST\u CODE；
公共类WordViewModel扩展了AndroidViewModel{
私有词存储库；
私有LiveData；
公共WordViewModel（应用程序）{
超级（应用）；
mRepository=新单词库（应用程序）；
mAllWords=mRepository.getAllWords（）；
}
公共静态无效删除（Word wordAt）{
}
LiveData getAllWords（）{return mAllWords；}
公共空白插入（Word）{mRepository.insert（Word）；}
}

这是我的WordRepository：

class WordRepository {

private WordDao mWordDao;
private LiveData<List<Word>> mAllWords;

// Note that in order to unit test the WordRepository, you have to remove the Application
// dependency. This adds complexity and much more code, and this sample is not about testing.
// See the BasicSample in the android-architecture-components repository at
// https://github.com/googlesamples
WordRepository(Application application) {
    WordRoomDatabase db = WordRoomDatabase.getDatabase(application);
    mWordDao = db.wordDao();
    mAllWords = mWordDao.getAlphabetizedWords();
}

// Room executes all queries on a separate thread.
// Observed LiveData will notify the observer when the data has changed.
LiveData<List<Word>> getAllWords() {
    return mAllWords;
}

// You must call this on a non-UI thread or your app will throw an exception. Room ensures
// that you're not doing any long running operations on the main thread, blocking the UI.
void insert(Word word) {
    WordRoomDatabase.databaseWriteExecutor.execute(() -> {
        mWordDao.insert(word);
    });
}
}

classwordrepository{
私人WordDao mWordDao；
私有LiveData；
//请注意，为了对WordRepository进行单元测试，必须删除应用程序
//这增加了复杂性和更多的代码，本示例与测试无关。
//请参阅android架构组件存储库中的BasicSample
// https://github.com/googlesamples
WordRepository（应用程序）{
WordRoomDatabase db=WordRoomDatabase.getDatabase（ap
class WordRepository {

private WordDao mWordDao;
private LiveData<List<Word>> mAllWords;

// Note that in order to unit test the WordRepository, you have to remove the Application
// dependency. This adds complexity and much more code, and this sample is not about testing.
// See the BasicSample in the android-architecture-components repository at
// https://github.com/googlesamples
WordRepository(Application application) {
    WordRoomDatabase db = WordRoomDatabase.getDatabase(application);
    mWordDao = db.wordDao();
    mAllWords = mWordDao.getAlphabetizedWords();
}

// Room executes all queries on a separate thread.
// Observed LiveData will notify the observer when the data has changed.
LiveData<List<Word>> getAllWords() {
    return mAllWords;
}

// You must call this on a non-UI thread or your app will throw an exception. Room ensures
// that you're not doing any long running operations on the main thread, blocking the UI.
void insert(Word word) {
    WordRoomDatabase.databaseWriteExecutor.execute(() -> {
        mWordDao.insert(word);
    });
}
}

import androidx.room.Query;

import java.util.List;

@Dao
public interface WordDao {

// allowing the insert of the same word multiple times by passing a
// conflict resolution strategy
@Insert(onConflict = OnConflictStrategy.IGNORE)
void insert(Word word);

@Query("DELETE FROM word_table")
void deleteAll();

@Query("SELECT * from word_table ORDER BY word ASC")
LiveData<List<Word>> getAlphabetizedWords();

@Delete
void delete(Word word);

public void delete(Word word) {
    WordRoomDatabase.databaseWriteExecutor.execute(() -> {
        mWordDao.delete(word);
    });
}

public void delete(Word word) {
    mRepository.delete(word); 
}

@Override
public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
    mWordViewModel.delete(adapter.getWordAt(viewHolder.getAdapterPosition()));
    Toast.makeText(TestGroceryList.this, "Item Deleted!", Toast.LENGTH_SHORT).show();

}