我有一个listview，每个列表项都有一个收藏夹按钮，单击该按钮后应将列表项添加到另一个名为我的收藏夹的 Activity 中。我正在使用Baseadapter作为listview，并使用Sharedpreference添加收藏夹。
当我单击“收藏夹”按钮时， ListView 项已添加到“收藏夹” Activity 中，但是我面临以下问题:
1)单击“收藏夹”按钮时，它应变暗，表明该列表项已添加到“收藏夹”中。发生这种情况，但是当我关闭 Activity 并再次返回时，按钮将恢复为原来的状态，而不是变暗
2)在我的收藏夹 Activity 中长按列表项时，应将列表项从收藏夹中删除，但这不会发生。
希望大家理解我的问题
我的密码
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;
}
}
我的最爱..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;
}
});
}
}
}
}
最佳答案
实际上，您的 saveFavorites()方法可以正常工作，因为您只需调用 gson.toJson()(将所有内容转换为json格式)
您想要使用SharedPreferences获取保存的数据，并且已使用此行来检索数据
gson.fromJson(jsonFavorites, CodeList[].class);
您永远不会用此行获取保存的数据，因为您保存了一个列表，并且想要检索一个数组 (!)
如果保存了列表，则必须使用列表 token 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。
关于android - 在 ListView 中添加收藏夹按钮，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/34470120/