如何使用 listview 项目 android 对 listview 进行排序？

Question

我有一个从数据库中填充的列表视图。该列表显示了可用的食物以及以下详细信息：

1. 准备食物的时间
2. 餐厅评分
3. 餐厅的纬度/经度
4. 食物的数量。

现在我想根据这四个项目对列表视图进行排序。我正在使用 ArrayList<HashMap<String, String>> 和扩展 baseadapter 的适配器。

我在 Collections.sort 中看到了很多关于 SO 的答案，但我未能在我的代码中实现它。

注意：我没有为 AvailableFood 对象定义数据模型来填充 arrayList。 这是我的代码：

AvailableFood.java

public class AvailableFood extends Fragment {

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

        mBottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
                switch (menuItem.getItemId()){
                    case R.id.nav_sort:
                        PopupMenu popup = new PopupMenu(getContext(), rootview.findViewById(R.id.nav_sort));
                        MenuInflater inflater = popup.getMenuInflater();
                        inflater.inflate(R.menu.sort_menu, popup.getMenu());
                        popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                            @Override
                            public boolean onMenuItemClick(MenuItem menuItem) {
                                switch (menuItem.getItemId()){
                                    case R.id.sort_recent: sortAvailableFood("Time");
                                        break;
                                    case R.id.sort_qty: sortAvailableFood("Qty");
                                        break;
                                    case R.id.sort_rating: sortAvailableFood("Rating");
                                        break;
                                    case R.id.sort_distance: sortAvailableFood("Distance");
                                        break;
                                }
                                return true;
                            }
                        });
                        popup.show();

                }
                return false;
            }

        });
        lvAvlFood = rootview.findViewById(R.id.list_avl_food);

        arrListAvlFood = new ArrayList<HashMap<String, String >>();
        arrListLoc = new ArrayList<HashMap<String, String>>();

        return rootview;
    }

    private void sortAvailableFood(String by) {
        switch (by){
            case"Time":
                break;
            case"Qty":case"Qty":
                Collections.sort(arrListAvlFood, new Comparator<HashMap<String, String>>() {
                    @Override
                    public int compare(HashMap<String, String> obj1, HashMap<String, String> obj2) {
                        if( Double.parseDouble(obj1.get(AvailableFood.KEY_QTY)) > Double.parseDouble(obj2.get(AvailableFood.KEY_QTY)) ) {
                            return 1;
                        }
                        else {
                            return 0;
                        }
                    }
                });
                AvlFoodAdapter sortedAdapter = new AvlFoodAdapter(getActivity(),arrListAvlFood);
                lvAvlFood.setAdapter(sortedAdapter);

                break;
            case"Rating":
                break;
            case"Distance":
                break;
        }
    }
}

LoadAllFood.java

class LoadAllFood extends AsyncTask<String, String, String>{

    @Override
    protected String doInBackground(String... strings) {
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            String ngoId = new SessionManager(getContext()).getUserId();
            if(ngoId != null || !ngoId.equals("")) {
                params.add(new BasicNameValuePair("n_id", ngoId));
            }
            JSONObject json = jParser.makeHttpRequest(url_avl_food, "GET", params);

            try {
                int success = json.getInt("success");

                if (success == 1) {

                    jaAvlFood = json.getJSONArray("avl_food");

                    // looping through All Food
                    for (int i = 0; i < jaAvlFood.length(); i++) {
                        JSONObject c = jaAvlFood.getJSONObject(i);


                        String prep_time = c.getString("prep_time");
                        String upload_time = c.getString("upload_time");
                        Double qty = c.getDouble("qty");
                        resName = c.getString("res_name");
                        String lat = c.getString("lat");
                        String longi = c.getString("longi");
                        String rating = c.getString("g_rating");

                        HashMap<String, String> map = new HashMap<String, String>();
                        HashMap<String, String> hmLatLong = new HashMap<String, String>();

                        map.put("f_id", f_id);


                        map.put("prep_time",prep_time);
                        map.put("upload_time",upload_time);
                        map.put("qty",qty.toString());
                        map.put("name",resName);
                        map.put("g_rating", rating);


                        hmLatLong.put("lat",lat);
                        hmLatLong.put("longi",longi);

                        arrListAvlFood.add(map);
                        arrListLoc.add(hmLatLong);
                    }
                } else {

                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
            return null;
    }  
}

Answer 1

为Food 创建一个模型类，它将包含其他数据成员并使您的代码更具可读性。

 class Food {
    Integer foodId;
    String preparedAt;
    String uploadedAt;
    String name;
    // other data members

    //constructor


    //setter for food id
    public setFoodId(id){
        this.foodId = id
    }
    //getter for food id
    public getFoodId(){
        return this.foodId
    }


    //setters and getters for other data members

    //toString() method
}

接下来在 LoadAllFoods 的 AsyncTask 中，您可以执行以下操作：

class LoadAllFood extends AsyncTask<Food, String, String>{
    @Override
    protected String doInBackground(Food... foods) {

    }
}

现在，您的列表视图只需要一个 List<Food>，您可以引用 preparedAt 的值或适配器类上的任何其他数据成员，执行以下操作：food.getFoodId();