ListView 不显示过滤结果

Question

所以，我在 Android Studio 的 MainActivity 中制作了一个包含 ListView 的应用，并且我在 android 中使用 SearchView 来过滤搜索结果。我的 ListView 包含图像和文本。我想根据文本搜索。参考下面的代码。当我按下搜索按钮并输入内容时，列表视图中什么都看不到。请查看并提出可行的解决方案。

这是我的 MainActivity ：

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference().child("temples");
ListView templeListView;
SearchView searchView;

List<Temple> temples = new ArrayList<>();

ItemAdapter itemAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //Navigation Drawer Logic

    Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    DrawerLayout drawer = findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.addDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

    //Initializing elements

    templeListView = findViewById(R.id.templeListView);

    //Getting Database Items

    templeListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

            Temple currentTemple = temples.get(position);

            Intent intent = new Intent(MainActivity.this, TempleDetails.class);

            intent.putExtra("templeName",currentTemple.getTempleName());
            intent.putExtra("templeAddress",currentTemple.getTempleAddress());
            intent.putExtra("templeImageURI",currentTemple.getTempleImageURI());
            intent.putExtra("latitude",currentTemple.getLatitude());
            intent.putExtra("longitude",currentTemple.getLongitude());

            startActivity(intent);
        }
    });

    //Setting Current Activity Items

    itemAdapter = new ItemAdapter(this, R.layout.list_item, temples);
    templeListView.setAdapter(itemAdapter);

    databaseReference.addChildEventListener(new ChildEventListener() {

        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {

            Temple temple = dataSnapshot.getValue(Temple.class);

            itemAdapter.add(temple);
        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

@Override
public void onBackPressed() {

    DrawerLayout drawer = findViewById(R.id.drawer_layout);

    if (drawer.isDrawerOpen(GravityCompat.START)) {

        drawer.closeDrawer(GravityCompat.START);
    }

    else {

        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);

    SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
    MenuItem searchItem = menu.findItem(R.id.search);
    searchView = (SearchView) searchItem.getActionView();

    assert searchManager != null;
    searchView.setSearchableInfo(searchManager.getSearchableInfo(getComponentName()));

    searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {

        @Override
        public boolean onQueryTextSubmit(String query) {

            return false;
        }

        @Override
        public boolean onQueryTextChange(String newText) {

            itemAdapter.getFilter().filter(newText);

            return false;
        }
    });

    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.search) {

        return true;
    }

    return super.onOptionsItemSelected(item);
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {

    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_share) {

        Intent intent = new Intent(Intent.ACTION_SEND);
        intent.setType("text/plain");

        String body = "108 Parshvanath Temples App \n\n" +
                "Get it now on play store : http://play.google.com/store/apps/details?id=ga.vihanggarud.www.a108parshvnath";

        intent.putExtra(Intent.EXTRA_TEXT,body);

        startActivity(Intent.createChooser(intent, "Share via"));
    }

    else if (id == R.id.nav_store) {

        try {

            startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=" + getPackageName())));
        }

        catch (ActivityNotFoundException e) {

            startActivity(new Intent(Intent.ACTION_VIEW,Uri.parse("http://play.google.com/store/apps/details?id=" + getPackageName())));
        }
    }

    else if (id == R.id.nav_about_us) {

        Intent intent = new Intent(MainActivity.this, AboutUs.class);
        startActivity(intent);
    }

    DrawerLayout drawer = findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}
}

这是我的适配器：

public class ItemAdapter extends ArrayAdapter<Temple> {

private Context context;

ItemAdapter(@NonNull Context context, int resource, @NonNull List<Temple> objects) {

    super(context, resource, objects);
    this.context = context;
}

public class ViewHolder {

    ImageView templeImage;
    TextView templeName;
}

@SuppressLint("InflateParams")
@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {

    ViewHolder holder;
    Temple temple = getItem(position);

    LayoutInflater inflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);

    if (convertView == null) {

        assert inflater != null;
        convertView = inflater.inflate(R.layout.list_item, null);

        holder = new ViewHolder();

        holder.templeName = convertView.findViewById(R.id.itemText);
        holder.templeImage = convertView.findViewById(R.id.itemImage);

        convertView.setTag(holder);
    }

    else
        holder = (ViewHolder) convertView.getTag();

    assert temple != null;
    holder.templeName.setText(temple.getTempleName());
    Glide.with(holder.templeImage.getContext())
            .load(temple.getTempleImageURI())
            .into(holder.templeImage);

    return convertView;
}
}

请询问您是否需要源代码中的其他内容。

Answer 1

您的adapter 必须实现Filterable。这是我从自己的一个项目中获取的一些示例代码，您必须将其调整为您的数据模型才能进行搜索，performFiltering 方法会迭代您的模型数组并将字段与约束进行比较。

public class MyAdapter extends RecyclerViewAdapter<MyModel, ViewHolder> implements Filterable {

    private AppFilter appFilter;
...
    @Override
    public Filter getFilter() {
        if (appFilter == null) {
            appFilter = new MyFilter();
        }

        return appFilter;
    }

    private class MyFilter extends Filter {

        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            FilterResults filterResults = new FilterResults();
            if (constraint != null && constraint.length() > 0) {
                ArrayList<MyModel> tempList = new ArrayList<>();

                // search content in friend list
                for (MyModel myModel : myModels) {
                    if (myModel.field.toLowerCase().contains(constraint.toString().toLowerCase())) {
                        tempList.add(myModel);
                    }
                }

                filterResults.count = tempList.size();
                filterResults.values = tempList;
            } else {
                filterResults.count = myModels.size();
                filterResults.values = myModels;
            }

            return filterResults;
        }

        /**
         * Notify about filtered list to ui
         *
         * @param constraint text
         * @param results    filtered result
         */
        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            filteredModels = (ArrayList<MyModel>) results.values;
            notifyDataSetChanged();
        }
    }

 }

根据@anthony 的评论，您必须包含可搜索的 xml。

<?xml version="1.0" encoding="utf-8"?>
<searchable xmlns:android="http://schemas.android.com/apk/res/android"
    android:hint="@string/search_hint"
    android:label="@string/search">
</searchable>