过滤

Question

我的应用程序中有一个Activity，用户从列表中搜索特定项目，但他也可以按城市列表中的那些项目。我正在做微调器。在他点击微调器对项目进行排序后，他再次从服务器获取数据。

在按城市排序列表中的项目之前搜索时会出现问题。过滤工作正常，但在我们过滤列表中的项目后，我不能再使用微调器并按所选城市获取有序数据。该列表显示了以spinner的默认值开头的先前记录。无法再获取数据。我不知道为什么。

这是该活动的代码：

public class SearchGroupsActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener, SearchView.OnQueryTextListener {

    Toolbar mToolbar;
    SessionManager mSessionManager;
    List<Group> mGroups;
    RecyclerView mList;
    RecyclerGroupsAdapter mAdapter;
    SharedPreferences mSharedPreferences;
    MyProgressDialog mDialog;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            Window w = getWindow(); // in Activity's onCreate() for instance
            w.setFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS, WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
        }
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search_groups);
        mSessionManager = new SessionManager(this);
        mSharedPreferences = new SharedPreferences(this);
        mGroups = new ArrayList<>();

        final SearchView searchView = (SearchView) findViewById(R.id.search);
        searchView.setIconifiedByDefault(false);
        searchView.setOnQueryTextListener(this);

        setAdapter();
        setToolbar();

        Spinner spinner = (Spinner) mToolbar.findViewById(R.id.spinner);
        spinner.setOnItemSelectedListener(this);
        // Create an ArrayAdapter using the string array and a default spinner layout
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
                R.array.group_cities, android.R.layout.simple_spinner_item);
        // Specify the layout to use when the list of choices appears
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        // Apply the adapter to the spinner
        spinner.setAdapter(adapter);

        if (!mSessionManager.isLoggedIn()) {
            startActivity(new Intent(this, LoginActivity.class));
            this.finish();
        }

    }

    private void setAdapter() {
        mList = (RecyclerView) findViewById(R.id.list);
        mAdapter = new RecyclerGroupsAdapter(this, mGroups);
        RecyclerView.LayoutManager manager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
        mList.setLayoutManager(manager);
        mList.setItemAnimator(new DefaultItemAnimator());
        mList.setAdapter(mAdapter);
    }

    private void loadGroups(String selectedCity) {
        mDialog = new MyProgressDialog(this, 1);
        mDialog.show();

        StringRequest stringRequest = new StringRequest(Request.Method.GET,
                AppConfig.ORDER_GROUPS_BY_CITY + "/" + selectedCity,
                new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                hidePDialog();

                if (mGroups.size() > 0) {
                    mGroups.clear();
                }

                try {
                    JSONObject object = new JSONObject(response);
                    boolean error = object.getBoolean("error");
                    JSONArray groups = object.getJSONArray("groups");
                    if (!error) {
                        for (int i = 0; i < groups.length(); i++) {
                            JSONObject groupObject = groups.getJSONObject(i);
                            Group group = new Group();
                            group.setGroupName(groupObject.optString("group_name"));
                            mGroups.add(group);
                        }
                    }

                    // notify adapter that data has changed
                    mAdapter.notifyDataSetChanged();
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                hidePDialog();
                Toast.makeText(SearchGroupsActivity.this, error.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });

        AppController.getInstance().addToRequestQueue(stringRequest);
    }

    private String orderGroupsByCity() {
        String cityName = "";
        int selectedFilterOption = mSharedPreferences.getCityFilter();

        switch (selectedFilterOption) {
            case 0:
                cityName = "Nis";
                break;
            case 1:
                cityName = "Beograd";
                break;
            case 2:
                cityName = "Paracin";
                break;
        }

        return cityName;
    }

    private void setToolbar() {
        mToolbar = (Toolbar) findViewById(R.id.toolbar);
        if (mToolbar != null) {
            setSupportActionBar(mToolbar);
        }
        getSupportActionBar().setHomeButtonEnabled(true);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setTitle("NADJI EKIPU");
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();

        switch (id) {
            case android.R.id.home:
                this.finish();
                break;
        }

        return false;
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        int selectedCityFilter = GroupsCity.NIS;
        switch (position) {
            case 0:
                // NIS
                selectedCityFilter = GroupsCity.NIS;
                break;
            case 1:
                // BEOGRAD
                selectedCityFilter = GroupsCity.BEOGRAD;
                break;
            case 2:
                // PARACIN
                selectedCityFilter = GroupsCity.PARACIN;
                break;
        }
        mSharedPreferences.setCityFilter(selectedCityFilter);
        String selectedCity = orderGroupsByCity();
        loadGroups(selectedCity); // HERE WE ARE FETCHING DATA ORDERED BY SELECTED CITY
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        hidePDialog();
    }

    private void hidePDialog() {
        if (mDialog != null) {
            mDialog.dismiss();
            mDialog = null;
        }
    }

    @Override
    public boolean onQueryTextSubmit(String query) {

        return false;
    }

    @Override
    public boolean onQueryTextChange(String newText) {
        final List<Group> filteredModelList = filter(mGroups, newText);
        mAdapter.setFilter(filteredModelList);

        return true;
    }

    private List<Group> filter(List<Group> groups, String query) {
        query = query.toLowerCase();

        final List<Group> filteredModelList = new ArrayList<>();
        for (Group group : groups) {
            final String text = group.getGroupName().toLowerCase();
            if (text.contains(query)) {
                filteredModelList.add(group);
            }
        }
        return filteredModelList;
    }
}

Answer 1

如果您首先搜索然后单击Spinner，您将过滤适配器（这将正常工作），然后您将向服务器执行该请求（当用户选择城市时）。

但是，当请求返回数据时，您当前只是将其添加到适配器不基于的groups列表中（我的假设是，当您进行过滤时传递新列表） 。因此，在这种情况下，简单地调用notifyDatasetChanged()将无用，因为适配器将无法看到新数据项。

为了解决这个问题，在你的loadGroups（）方法中你需要再次通过调用filter()方法进行过滤，并在适配器上设置结果列表（就像你目前在监听器中那样做搜索查看）。