使用共享首选项添加 listvview 的收藏夹

Question

我有一个使用 baseadapter 的列表视图。长按时，每个列表项都应使列表项添加到另一个活动中显示的收藏夹。长按列表项时，列表项末尾的星形图像应变暗，表示列表项已添加到收藏夹。这确实发生了，但是当我退出列表视图活动并再次重新打开它时，星形图像不再黑暗 顺便说一句，我使用解析。 com 接收列表中的信息

我的代码

ssharedpreference.java

public class SharedPreference
{

public static final String PREFS_NAME = "POCKTCODE_APP";
public static final String FAVORITES = "code_Favorite";

public SharedPreference(){
    super();
}

public void saveFavorites(Context context, List<CodeList> favorites){
    SharedPreferences settings;
    Editor editor;

    settings = context.getSharedPreferences(PREFS_NAME,
                                            Context.MODE_PRIVATE);
    editor = settings.edit();

    Gson gson = new Gson();
    String jsonFavorites = gson.toJson(favorites);

    editor.putString(FAVORITES, jsonFavorites);

    editor.commit();
}

public void addFavorite(Context context, CodeList code){
    List<CodeList> favorites = getFavorites(context);

    if(favorites == null)
        favorites = new ArrayList<CodeList>();
    favorites.add(code);
    saveFavorites(context,favorites);
}

public void removeFavorite(Context context, CodeList code) {
    ArrayList<CodeList> favorites = getFavorites(context);
    if (favorites != null) {
        favorites.remove(code);
        saveFavorites(context, favorites);
    }
}


public ArrayList<CodeList> getFavorites(Context context) {
    SharedPreferences settings;
    List<CodeList> favorites;

    settings = context.getSharedPreferences(PREFS_NAME,
                                            Context.MODE_PRIVATE);

    if (settings.contains(FAVORITES)) {
        String jsonFavorites = settings.getString(FAVORITES, null);
        Gson gson = new Gson();
        CodeList[] favoriteItems = gson.fromJson(jsonFavorites,
                                                 CodeList[].class);

        favorites = Arrays.asList(favoriteItems);
        favorites = new ArrayList<CodeList>(favorites);
    } else
        return null;

    return (ArrayList<CodeList>) favorites;
}

}

我的 baseadapter 的必需部分

@Override
public View getView(final int position, View view, ViewGroup parent)
{
    final ViewHolder holder;
    if(view == null){
        holder = new ViewHolder();
        view = inflater.inflate(R.layout.beg_list_item,null);
        holder.listHeading = (TextView) view.findViewById(R.id.beg_list_itemTextView);

        //holder.listHash = (TextView) view.findViewById(R.id.listview_hashtags);
        holder.alphabetList = (ImageView) view.findViewById(R.id.beg_list_itemImageView);
        view.setTag(holder);
        holder.favariteImage = (ImageView) view.findViewById(R.id.favbtn);

    }else{
        holder = (ViewHolder) view.getTag();
    }
    CodeList codes = (CodeList) getItem(position);
    holder.listHeading.setText(codeList.get(position).getListHeading());
    imageLoader.DisplayImage(codeList.get(position).getAlphabetimg(),
                             holder.alphabetList);


    if (checkFavoriteItem(codes)) {
        holder.favariteImage.setImageResource(R.drawable.favorite);
        holder.favariteImage.setTag("yes");
    } else {
        holder.favariteImage.setImageResource(R.drawable.unfavorite);
        holder.favariteImage.setTag("no");
    }                    

    view.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View arg0){
                Intent intent = new Intent(context, SingleItemView.class);

                //
                intent.putExtra("demovideo",
                                (codeList.get(position).getDailogdemovideo()));

                intent.putExtra("download",
                                (codeList.get(position).getDownloadCode()));


                intent.putExtra("videoimg",
                                (codeList.get(position).getVideoImage()));



                // Start SingleItemView Class
                context.startActivity(intent);

            }
        });             
        view.setOnLongClickListener(new OnLongClickListener(){
            @Override
            public boolean onLongClick(View v){

                ImageView fvrtebutton = (ImageView) v.findViewById(R.id.favbtn);

                String tag = fvrtebutton.getTag().toString();
                if (tag.equalsIgnoreCase("no")) {
                    shrdprfrnce.addFavorite(context, codeList.get(position));
                    Toast.makeText(context, R.string.fav_added,
                                   Toast.LENGTH_SHORT).show();

                    fvrtebutton.setTag("yes");
                    fvrtebutton.setImageResource(R.drawable.favorite);
                } else {
                    shrdprfrnce.removeFavorite(context, codeList.get(position));
                    fvrtebutton.setTag("no");
                    fvrtebutton.setImageResource(R.drawable.unfavorite);
                    Toast.makeText(context,
                                   R.string.fav_removed,
                                   Toast.LENGTH_SHORT).show();
                }
                return false;
            }
        });


    return view;
}
//to check whether list item exists in shared preferences
public boolean checkFavoriteItem(CodeList checkProduct) {
    boolean check = false;
    List<CodeList> favorites = shrdprfrnce.getFavorites(context);
    if (favorites != null) {
        for (CodeList codes : favorites) {
            if (codes.equals(checkProduct)) {
                check = true;
                break;
            }
        }
    }
    return check;
}


public void add(CodeList codes) {
    //super.add(codes);
    codeList.add(codes);
    notifyDataSetChanged();
}


public void remove(CodeList codes) {
    //super.remove(codes);
    codeList.remove(codes);
    notifyDataSetChanged();
}   

我最喜欢的活动

public class MyFavActivity extends Activity
 {
@Override
protected void onCreate(Bundle savedInstanceState)
{
    ListView favoriteList;
    final SharedPreference shrdprefernces;
    final List<CodeList> favorites;
    final FinalAdapter fnladpter;


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

    shrdprefernces= new SharedPreference();
    favorites = shrdprefernces.getFavorites(MyFavActivity.this);

    if (favorites == null) {
        showAlert(getResources().getString(R.string.nofav),
                  getResources().getString(R.string.nofavmsg));
    } else {

        if (favorites.size() == 0) {
            showAlert(
                getResources().getString(R.string.nofav),
                getResources().getString(R.string.nofavmsg));
        }

        favoriteList = (ListView) findViewById(R.id.favlayoutListView);
        if (favorites != null) {
            fnladpter = new FinalAdapter(MyFavActivity.this, favorites);
            favoriteList.setAdapter(fnladpter);

            favoriteList.setOnItemClickListener(new OnItemClickListener() {

                    public void onItemClick(AdapterView<?> parent, View arg1,
                                            int position, long arg3) {

                    }
                });

            favoriteList
                .setOnItemLongClickListener(new OnItemLongClickListener() {

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

                        ImageView button = (ImageView) view
                            .findViewById(R.id.favbtn);

                        String tag = button.getTag().toString();
                        if (tag.equalsIgnoreCase("no")) {
                            shrdprefernces.addFavorite(MyFavActivity.this,
                                                         favorites.get(position));
                            Toast.makeText(
                                MyFavActivity.this,
                                getString(
                                    R.string.fav_added),
                                Toast.LENGTH_SHORT).show();

                            button.setTag("yes");
                            button.setImageResource(R.drawable.favorite);
                        } else {
                            shrdprefernces.removeFavorite(MyFavActivity.this,
                                                            favorites.get(position));
                            button.setTag("no");
                            button.setImageResource(R.drawable.unfavorite);
                            fnladpter.remove(favorites
                                                      .get(position));
                            Toast.makeText(
                                MyFavActivity.this,
                                getString(
                                    R.string.fav_removed),
                                Toast.LENGTH_SHORT).show();
                        }
                        return true;
                    }
                });
        }
    }
}

public void showAlert(String title, String message) {
    if (MyFavActivity.this != null && !MyFavActivity.this.isFinishing()) {
        AlertDialog alertDialog = new AlertDialog.Builder(MyFavActivity.this)
            .create();
        alertDialog.setTitle(title);
        alertDialog.setMessage(message);
        alertDialog.setCancelable(false);

        // setting OK Button
        alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "OK",
            new DialogInterface.OnClickListener() {

                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                    // activity.finish();
                    getFragmentManager().popBackStackImmediate();
                }
            });
        alertDialog.show();
    }
}

@Override
protected void onResume()
{
    // TODO: Implement this method
    super.onResume();
}


@Override
public void onBackPressed() {
    super.onBackPressed();
    overridePendingTransition(R.anim.left_to_right, R.anim.right_to_left); 

}

 }

Answer 1

在阅读本文之前，如果您不知道如何创建数据库，请关注this 链接。

好的，让我们开始在数据库中存储一些收藏夹..

您还应该从 json 中解析 post 的 id 并将其存储在数据库的第一个表中，以便稍后将该 id 与用于存储收藏夹的第二个表中的行 id 进行比较。

创建表格

这是我的桌子

// CREATE TABLES
private static final String CREATE_FUN_FACTS_TABLE = "CREATE TABLE " + TABLE_NAME + "("
        + KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
        + POST_ID + " INTEGER,"
        + KEY_DESC + " TEXT,"
        + KEY_IMAGE + " TEXT,"
        + KEY_SOURCE + " TEXT" + ")";

private static final String CREATE_FAVS_TABLE = "CREATE TABLE " + TABLE_FAVS + "("
        + FAVS_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
        + FACTS_ID + " INTEGER" + ")";

现在让我们在第一个表中添加一些项目

// ADDING NEW FACTS ITEM
public void addItem(FunFactsData item) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(POST_ID, item.getId());
    values.put(KEY_DESC, item.getDescription());
    values.put(KEY_IMAGE, item.getImagePath());
    values.put(KEY_SOURCE, item.getSource());
    // INSERTING ROW
    db.insert(TABLE_NAME, null, values);
    db.close(); // CLOSING DATABASE CONNECTION
}

现在让我们在第二张表中添加一些收藏夹

// ADDING NEW FAVORITE
public void addToFavorite(FunFactsData savedItem) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(FACTS_ID, savedItem.getId());
    // INSERTING ROW
    db.insert(TABLE_FAVS, null, values);
    db.close();
}

从收藏夹中删除项目的方法

// REMOVING FROM FAVORITE
public void removeFromFavorite(FunFactsData removedItem) {
    SQLiteDatabase db = this.getWritableDatabase();
    db.delete(TABLE_FAVS, FACTS_ID + " = ? ",
            new String[]{String.valueOf(removedItem.getId())});
    db.close();
}

这是获取所有收藏夹的方法

// GETTING ALL FAVORITES
public List<FunFactsData> getFavorites() {
    List<FunFactsData> funFactsDataList = new ArrayList<>();

    // BUILD THE QUERY
    String query = "SELECT * FROM " + TABLE_NAME;
    String query2 = " INNER JOIN " + TABLE_FAVS;
    String query3 = " ON " + POST_ID + " = " + FACTS_ID + " GROUP BY " + FACTS_ID;

    // GET REFERENCE TO WRITABLE DB
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(query + query2 + query3, null);

    // GO OVER EACH ROW, AND GET FAVORITES FROM FAVORITES TABLE
    FunFactsData fact;
    if (cursor.moveToFirst()) {
        do {
            fact = new FunFactsData();
            fact.setId(cursor.getInt(1));
            fact.setDescription(cursor.getString(2));
            fact.setImagePath(cursor.getString(3));
            fact.setSource(cursor.getString(4));

            funFactsDataList.add(fact);
        } while (cursor.moveToNext());
    }

    return funFactsDataList;
}

从数据库中获取所有项目的方法

// GET ALL DATA FROM DATABASE
public List<FunFactsData> getAllFunFacts() {
    List<FunFactsData> funFactsDataList = new ArrayList<>();

    // 1. BUILD THE QUERY
    String query = "SELECT * FROM " + TABLE_NAME;

    // 2. GET REFERENCE TO WRITABLE DB
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(query, null);

    // 3. GO OVER EACH ROW, BUILD FUN FACTS AND ADD IT TO LIST
    FunFactsData fact;
    if (cursor.moveToFirst()) {
        do {
            fact = new FunFactsData();
            fact.setId(cursor.getInt(1));
            fact.setDescription(cursor.getString(2));
            fact.setImagePath(cursor.getString(3));
            fact.setSource(cursor.getString(4));

            // Add fun fac to facts
            funFactsDataList.add(fact);
        } while (cursor.moveToNext());
    }

    Log.d("getAllFunFacts()", funFactsDataList.toString());

    // RETURN FACT
    return funFactsDataList;
}

这就是我们将从 JSON 解析到数据库的项目存储的方式

@Override
public void getData(String link) {
    try {
        JSONObject response = new JSONObject(link);
        JSONArray posts = response.getJSONArray("posts");
        facts = new ArrayList<>();

        shuffleJsonArray(posts);
        for (int i = 0; i < posts.length(); i++) {
            JSONObject obj = posts.getJSONObject(i);
            JSONObject customFields = obj.getJSONObject("custom_fields");

            FunFactsData funFactsData = new FunFactsData();
            funFactsData.setId(obj.getInt("id"));
            funFactsData.setImagePath(obj.getString("thumbnail"));
            funFactsData.setDescription(customFields.optString("description"));
            funFactsData.setSource(customFields.optString("source"));

            facts.add(funFactsData);
            dataBase.deleteRecords(); // "DELETE FROM " + TABLE_NAME, so everytime we get data from json, we will delete records from database and store new, but as far as we got id of post, we are good!
            for (FunFactsData data : facts) { // go through loop for getting all objects and add them to database
                dataBase.addItem(data); // add items do database
            }
            facts = (ArrayList<FunFactsData>) dataBase.getAllFunFacts(); // retrieve items from database
            adapter = new FunFactsListAdapter(HomeActivity.this, facts);
            flyingContainer.setAdapter(adapter); // setting addapter
            loadMoreData.setVisibility(View.INVISIBLE);
            noMoreData.setVisibility(View.INVISIBLE);
        }

        hidePDialog();
        adapter.notifyDataSetChanged();

    } catch (Exception e) {
        e.printStackTrace();
    }
}

现在我们进入存储收藏夹的部分

我已经在我的适配器中为此编写了逻辑，所有的魔法都在那里发生..

// Here we are checking if item with specified post id we are getting from json exists in second database.
private boolean checkFavoriteItem(FunFactsData checkItem) {
    boolean check = false;
    List<FunFactsData> facts = dataBase.getFavorites();
    if (facts != null) {
        for (FunFactsData data : facts) {
            int id = data.getId();
            int id2 = checkItem.getId();
            if (id == id2) {
                check = true;
                break;
            }
        }
    }
    return check;
}

// Here i'm storing item to favorite
holder.favoriteIcon.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String getTag = holder.favoriteIcon.getTag().toString();
            if (getTag.equalsIgnoreCase("gray")) {
                dataBase.addToFavorite(data);
                toast(context.getString(R.string.add_favorite));
                holder.favoriteIcon.setTag("red");
                holder.favoriteIcon.setImageResource(R.drawable.heart_red);
            } else {
                dataBase.removeFromFavorite(data);
                toast(context.getString(R.string.remove_favorite));
                holder.favoriteIcon.setTag("gray");
                holder.favoriteIcon.setImageResource(R.drawable.heart);
            }
            mSmallBang.bang(v);
        }
    });

    // i think this is clear also what i'm doing here.
    if (checkFavoriteItem(data)) {
        holder.favoriteIcon.setImageResource(R.drawable.heart_red);
        holder.favoriteIcon.setTag("red");
    } else {
        holder.favoriteIcon.setImageResource(R.drawable.heart);
        holder.favoriteIcon.setTag("gray");
    }

希望你能根据我的代码管理你的代码并解决你的问题！

更新

mRecyclerView.addOnItemTouchListener(new GiftsFavoriteList.RecyclerTouchListener(TagGiftsActivity.this, mRecyclerView, new GiftsFavoriteList.ClickListener() {
        @Override
        public void onClick(View view, int position) {
            Intent intent = new Intent(TagGiftsActivity.this, GiftSingleActivity.class);
            GiftItem selectedItem = mAdapter.getItem(position); // you can create method in adapter for getting specific item in row or use this -- arrayList.get(position); That is the same. I just used this in adapter.
            intent.putExtra("selected_item", selectedItem);
            startActivity(intent);
        }

然后你需要像这样让你的类实现 Serializable：

public class YourClass implements Serializable

接下来，我们需要从这个活动中获取意图到我们正在接收你的类对象的活动..

// GETTING INTENT FROM PREVIOUS ACTIVITY
    final Intent i = getIntent();

// GETTING POSITION OF SELECTED ITEM
    GiftItem selectedItem = (GiftItem) i.getSerializableExtra("selected_item");

我在适配器中用于检查收藏项的相同逻辑是在单个视图项中。这里我们也检查item是否在收藏夹中，所以我们可以设置合适的图片资源。

if (checkFavoriteItem(selectedItem)) {
        favorite.setImageResource(R.drawable.ic_favorite);
        favorite.setTag("red");
    } else {
        favorite.setImageResource(R.drawable.ic_add_favorite);
        favorite.setTag("gray");
    }

在这里我们将项目添加到收藏夹：

String tag = favorite.getTag().toString();
        if (tag.equalsIgnoreCase("gray")) {
            dbh.addToFavorite(selectedItem);
            toast("Added to favorites!");
            favorite.setImageResource(R.drawable.ic_favorite);
            favorite.setTag("red");
        } else {
            dbh.removeFromFavorite(selectedItem);
            toast("Removed from favorites!");
            favorite.setImageResource(R.drawable.ic_add_favorite);
            favorite.setTag("gray");
        }
    }

Answer 2

制作一个数组列表/数组用于存储收藏夹位置并在长按时添加位置并将其保存在共享偏好中。当您再次导航到该活动时，首先检查收藏列表是否有任何项目。如果它比更改该位置的最喜欢的图标

Answer 3

首先，您需要将最喜欢的项目存储在另一个列表中，然后将 arraylist 存储在 sharedpreferences 中，然后在另一个列表中显示共享首选项数据。

Answer 4

在您的 getFavorites(Context context) 方法中

而不是这个

favorites = Arrays.asList(favoriteItems);
favorites = new ArrayList<CodeList>(favorites);

使用这个

favorites  = new ArrayList<CodeList>();
favorites.addAll(Arrays.asList(favoriteItems));

和

return favorites;