java - 我的 RecyclerView 在过滤后不断重置

Question

我有一个可用的 RecyclerView，我需要实现一个搜索栏。我设法用 EditText 和 TextWatcher 创建一个搜索栏，但遇到以下问题:

通常，我的列表根据当前项目的位置传递数据，当我过滤列表时，位置当然会搞砸。

我遵循了一些指南，发现了这个解决方法:

private void filter(String text){
    ArrayList<Item> filteredList = new ArrayList<>();

    for (Item item : mList ) {
        if(item.getName().toLowerCase().contains(text.toLowerCase())) {
            filteredList.add(item);
        }
    }
    mListAdapter.filterList(filteredList);

    //when the app is done filtering, it clears the existing ArrayList and it adds just the filtered Items

    mList.clear();
    mList.addAll(filteredList);
}

这种方法的问题在于，当 mList.clear() 发生时，我会丢失所有数据，只保留过滤后的数据。然后，当我从搜索栏中删除文本时，我所拥有的只是一个空的 RecyclerView。

我考虑过当 EditText 为空时尝试将列表重置为原始状态，但我不知道该怎么做，而且这并不理想。

有人能想出办法解决这个问题吗？我真的很绝望:D

我的 RecyclerView 类:

public class ListFragment extends Fragment {

static final String EXTRA_NAME = "monumentname";
static final String EXTRA_NUMBER = "monumentnumber";
static final String EXTRA_REGION = "monumentregion";
static final String EXTRA_REGION2 = "monumentregion2";
static final String EXTRA_TOWN = "monumenttown";
static final String EXTRA_DESCRIPTION = "monumentdescription";
static final String EXTRA_WEB = "web";

private ListAdapter mListAdapter;
private ArrayList<Item> mList;
private RequestQueue mRequestQueue;
private Context mContext;
private InternetCheck internetCheck = new InternetCheck();


@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable final Bundle savedInstanceState) {
    View rootview = inflater.inflate(R.layout.fragment_list, container, false);

    RecyclerView mRecyclerView = rootview.findViewById(R.id.recycler_view);
    mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    Button syncData = rootview.findViewById(R.id.sync_button);
    final ProgressBar progressBar = rootview.findViewById(R.id.progressbar);
    EditText editText = rootview.findViewById(R.id.edittext);

    editText.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

        }

        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

        }

        @Override
        public void afterTextChanged(Editable s) {
            filter(s.toString());
        }
    });

..........some other irrelevant stuff here


    mListAdapter.setOnItemClickListener(new ListAdapter.OnItemClickListener() {
        @Override
        public void onItemClick(int position) {
            Intent detailIntent = new Intent(getActivity(), SingleItem.class);
            Item clickedItem = mList.get(position);

            detailIntent.putExtra(EXTRA_NAME, clickedItem.getName());
            detailIntent.putExtra(EXTRA_NUMBER, clickedItem.getNumber());
            detailIntent.putExtra(EXTRA_REGION, clickedItem.getRegion());
            detailIntent.putExtra(EXTRA_REGION2, clickedItem.getRegion2());
            detailIntent.putExtra(EXTRA_TOWN, clickedItem.getTown());
            detailIntent.putExtra(EXTRA_DESCRIPTION, clickedItem.getDescription());
            detailIntent.putExtra(EXTRA_WEB, clickedItem.getWeb());

            startActivity(detailIntent);
        }
    });


    return rootview;
}

.......some onCreateView and stuff like that here

public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    loadData();
    mListAdapter = new ListAdapter(mContext, mList);
    mRequestQueue = Volley.newRequestQueue(mContext);

}

private void parseJSON() {

    JsonObjectRequest request = new JsonObjectRequest("http://192.168.0.105/sestavsisvujsvetweb/api/seznammagnetek", null, new Response.Listener<JSONObject>() {

.....parsing my JSON here



    mRequestQueue.add(request);

}

private CharSequence removeHtmlFrom(String html) {
    return new HtmlCleaner().clean(html).getText();
}

@Override
public void onStop() {
    super.onStop();
    saveData();
}


private void saveData() {
    SharedPreferences sharedPreferences = getContext().getSharedPreferences("shared preferences", MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    Gson gson = new Gson();
    String json = gson.toJson(mList);
    editor.putString("seznam magnetek", json);
    editor.apply();
}

private void loadData() {
    SharedPreferences sharedPreferences = getContext().getSharedPreferences("shared preferences", MODE_PRIVATE);
    Gson gson = new Gson();
    String json = sharedPreferences.getString("seznam magnetek", null);
    Type type = new TypeToken<ArrayList<Item>>() {
    }.getType();
    mList = gson.fromJson(json, type);

    if (mList == null || mList.isEmpty()) {
        Toast.makeText(getContext(), "Seznam magnetek je prázdný. Aktualizujte prosím data z databáze.", Toast.LENGTH_SHORT).show();
        mList = new ArrayList<>();
    }
}

private void filter(String text) {
    ArrayList<Item> filteredList = new ArrayList<>();

    for (Item item : mList) {
        if (item.getName().toLowerCase().contains(text.toLowerCase())) {
            filteredList.add(item);
        }
    }
    mListAdapter.filterList(filteredList);
    mList.clear();
    mList.addAll(filteredList);
}

}

Answer 1

这里有 2 个潜在问题:

1. 将filteredList传递给mListAdapter后，您必须调用adapter.notifyDataSetChanged notifyDataSetChanged使 ListView 无效。
2. 此外，将过滤后的列表添加到适配器后，您不需要清除mList。由于 loadData 仅调用一次，因此如果您第一次清除此设置，列表中将仅保留过滤后的项目。即使您删除过滤字符串，该项目也不会添加回mList。

请尝试添加以下内容:

private void filter(String text){
    ArrayList<Item> filteredList = new ArrayList<>();

    for (Item item : mList ) {
        if(item.getName().toLowerCase().contains(text.toLowerCase())) {
            filteredList.add(item);
        }
    }
    mListAdapter.filterList(filteredList);
    mListAdapter.notifyDataSetChanged();
}