我有一个使用 baseadapter 的 ListView 。长按时每个列表项应使列表项添加到另一个 Activity 中显示的收藏夹。当长按列表项时，列表项末尾的星形图像应该变暗，表示列表项已添加到收藏夹。这确实发生了，但是当我退出 ListView Activity 并再次重新打开它时，星形图像不再暗了 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;
}
}
需要我的 baseadapter 的一部分
@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 Activity
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);
}
}
最佳答案
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。
好吧，让我们开始在数据库中存储一些收藏夹..
您还应该从 json 中解析帖子的 ID，并将其存储在数据库的第一个表中，以便您稍后可以将该 ID 与第二个表中用于存储收藏夹的行的 ID 进行比较。
创建表
这些是我的表格
// 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
// 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 解析的项目存储到数据库的方式
@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();
}
}
现在我们开始存储收藏夹的部分
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");
}
我希望你能根据我的代码来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);
}
然后你需要让你的类像这样实现 Serializable:
public class YourClass implements Serializable
接下来，我们需要从这个 Activity 中获取 Intent 到我们正在接收您类(class)对象的 Activity 中......
// 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最喜欢的项目的相同逻辑是在单个 View 项目中。这里我们还检查项目是否在收藏夹中，因此我们可以设置适当的图像资源。
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");
}
}
关于android - 使用共享首选项添加 listvview 的收藏夹，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34544743/