在列表视图中添加收藏按钮
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【中文标题】在列表视图中添加收藏按钮【英文标题】：Adding favorite button in list view 【发布时间】：2016-03-31 22:07:00 【问题描述】：我有一个listview，它对每个列表项都有一个收藏按钮，单击该按钮应将该列表项添加到另一个名为 my fav9rites 的活动中。我将Baseadapter 用于listview 和Sharedpreference 用于添加收藏夹。
当我单击收藏按钮时，列表视图项目被添加到我的收藏活动中，但我面临以下问题：
1) 收藏按钮在点击时会变暗，表示列表项已添加到收藏夹。发生这种情况，但是当我关闭活动并再次返回时，按钮会恢复而不是变暗
2）在我的收藏夹活动中长按列表项，列表项应该从收藏夹中删除，但这不会发生。
希望大家理解我的问题
我的代码
我的基本适配器
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);
holder.favoriteImg = (ImageView) view.findViewById(R.id.favbtn);
view.setTag(holder);
else
holder = (ViewHolder) view.getTag();
CodeList code = (CodeList) getItem(position);
holder.listHeading.setText(codeList.get(position).getListHeading());
imageLoader.DisplayImage(codeList.get(position).getAlphabetimg(),
holder.alphabetList);
// holder.listHash.setText(codeList.get(position).getListHashTags());
if (checkFavoriteItem(code))
holder.favoriteImg.setImageResource(R.drawable.favorite);
holder.favoriteImg.setTag("yes");
else
holder.favoriteImg.setImageResource(R.drawable.unfavorite);
holder.favoriteImg.setTag("no");
view.setOnClickListener(new OnClickListener()
@Override
public void onClick(View arg0)
Intent intent = new Intent(context, SingleItemView.class);
//intent.putExtra("listheading",
// (codeList.get(position).getListHeading()));
//intent.putExtra("alphabetimg",
// (codeList.get(position).getAlphabetimg()));
intent.putExtra("demovideo",
(codeList.get(position).getDailogdemovideo()));
intent.putExtra("download",
(codeList.get(position).getDownloadCode()));
// Start SingleItemView Class
context.startActivity(intent);
);
final ImageView favoritesbutton = (ImageView) view.findViewById(R.id.favbtn);
favoritesbutton.setOnClickListener(new OnClickListener()
@Override
public void onClick(View v)
String tag = favoritesbutton.getTag().toString();
if(tag.equalsIgnoreCase("no"))
shrdPrefence.addFavorite(context, codeList.get(position));
Toast.makeText(context, R.string.fav_added, Toast.LENGTH_SHORT).show();
favoritesbutton.setTag("yes");
favoritesbutton.setImageResource(R.drawable.favorite);
else
shrdPrefence.removeFavorite(context, codeList.get(position));
favoritesbutton.setTag("no");
favoritesbutton.setImageResource(R.drawable.unfavorite);
Toast.makeText(context, R.string.fav_removed, Toast.LENGTH_SHORT).show();
);
return view;
//Checks whether a particular product exists in SharedPreferences*/
public boolean checkFavoriteItem(CodeList checkCode)
boolean check = false;
List<CodeList> favorites = shrdPrefence.getFavorites(context);
if (favorites != null)
for (CodeList code : favorites)
if (code.equals(checkCode))
check = true;
break;
return check;
public void add(CodeList code)
codeList.add(code);
notifyDataSetChanged();
public void remove(CodeList code)
codeList.remove(code);
notifyDataSetChanged();
sharedpreference.java
public class SharedPreference
public static final String PREFS_NAME = "MY_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;
我最喜欢的..java
public class MyFavActivity extends Activity
SharedPreference shrdPrfence;
List<CodeList> favorites;
FinalAdapter fnlAdpter;
Context context = this.context;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.fav_layout);
shrdPrfence = new SharedPreference();
favorites = shrdPrfence.getFavorites(MyFavActivity.this);
if(favorites == null)
Dialog dialog = new Dialog(MyFavActivity.this);
dialog.setTitle(R.string.nofav_title);
dialog.show();
else
if(favorites.size() == 0)
Dialog dialog = new Dialog(MyFavActivity.this);
dialog.setTitle(R.string.nofav_title);
dialog.show();
ListView favList = (ListView) findViewById(R.id.fav_layoutListView);
if(favorites != null)
fnlAdpter = new FinalAdapter(MyFavActivity.this, favorites);
favList.setAdapter(fnlAdpter);
favList.setOnItemClickListener(new OnItemClickListener()
public void onItemClick(AdapterView<?> parent, View arg1,
int position, long arg3)
);
favList.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"))
shrdPrfence.addFavorite(MyFavActivity.this,
favorites.get(position));
Toast.makeText(
MyFavActivity.this,
R.string.fav_added,
Toast.LENGTH_SHORT).show();
button.setTag("yes");
button.setImageResource(R.drawable.favorite);
else
shrdPrfence.removeFavorite(MyFavActivity.this,
favorites.get(position));
button.setTag("no");
button.setImageResource(R.drawable.unfavorite);
fnlAdpter.remove(favorites.get(position));
Toast.makeText(
MyFavActivity.this,
R.string.fav_removed,
Toast.LENGTH_SHORT).show();
return true;
);
【问题讨论】：
您检查过code.equals(checkCode) 是否有效吗？你实现了.equals 方法了吗？
@Roshan 是的，检查过。它有效
【参考方案1】：
实际上您的 saveFavorites() 方法工作正常，因为您只需调用 gson.toJson() （将所有内容转换为 json 格式）
您想使用 SharedPreferences 获取保存的数据，并且您已使用此行检索数据
gson.fromJson(jsonFavorites, CodeList[].class);
你永远不会用这一行得到你保存的数据，因为你保存了一个 list 并且你想检索一个 array (!)
如果您保存了列表，则必须使用列表令牌检索数据。你需要这条线
gson.fromJson(jsonFavorites,new TypeToken<ArrayList<CodeList>>() .getType());
我认为这将解决您的问题。祝你好运。
【讨论】：
感谢您的帮助。正如你所说的那样尝试了，但是当我打开我的收藏夹活动时，应用程序崩溃了，我在 logcat 中得到了这个。无法启动活动 ComponentInfocom.enlightenme.pac/com.enlightenme.pac.MyFavActivity：java.lang.ClassCastException：java.util.ArrayList 无法转换为 com.enlightenme.pac.CodeList[]以上是关于在列表视图中添加收藏按钮的主要内容，如果未能解决你的问题，请参考以下文章