使用房间数据库添加到收藏夹

Question

我指的是本教程===>https://uniqueandrocode.com/add-to-favourites-and-display-favourites-in-recyclerview/在我的项目中，我有底部导航。。。我正在尝试在第一个选项卡中添加收藏夹，并在底部导航栏的第二个选项卡中显示收藏夹。我正在使用Room图书馆。

当活动加载时，收藏夹一开始都是空白的，但当我第一行为收藏夹并转到收藏夹选项卡时，它会正确显示，但当回到第一个选项卡时，会自动填充所有收藏夹图标(我没有这样做，我只做了第一行(

真的需要帮助。提前谢谢。

刀：

@Dao
public interface FavoriteDao {
@Insert
public void addData(FavoriteList favoriteList);
@Query("select * from favoritelist")
public List<FavoriteList> getFavoriteData();
@Query("SELECT EXISTS (SELECT 1 FROM favoritelist WHERE id=:id)")
public int isFavorite(int id);
@Delete
public void delete(FavoriteList favoriteList);
}

数据库：

@Database(entities={FavoriteList.class},version = 1)
public abstract class FavoriteDatabase extends RoomDatabase {
public abstract FavoriteDao favoriteDao();
}

收藏夹列表：

@Entity(tableName="favoritelist")
public class FavoriteList {

@PrimaryKey
private int id;
@ColumnInfo(name = "source")
private String source;
@ColumnInfo(name = "author")
private String author;
@ColumnInfo(name = "title")
private String title;

@ColumnInfo(name = "description")
private String description;
@ColumnInfo(name = "url")
private String url;
@ColumnInfo(name = "urlToImage")
private String urlToImage;
@ColumnInfo(name = "publishedAt")
private String publishedAt;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getSource() {
return source;
}
public void setSource(String source) {
this.source = source;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public String getUrlToImage() {
return urlToImage;
}
public void setUrlToImage(String urlToImage) {
this.urlToImage = urlToImage;
}
public String getPublishedAt() {
return publishedAt;
}
public void setPublishedAt(String publishedAt) {
this.publishedAt = publishedAt;
}
}

新闻片段：

public class news extends Fragment {
ImageView favbtn;
RecyclerView recyclerView;
SwipeRefreshLayout swipeRefreshLayout;
EditText etQuery;
Button btnSearch;

Adapter adapter;
List<Articles> articles = new ArrayList<>();
public static FavoriteDatabase favoriteDatabase;

public news() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_news, container, false);
swipeRefreshLayout = view.findViewById(R.id.swiprefresh);
etQuery = view.findViewById(R.id.etQuery);
btnSearch = view.findViewById(R.id.btnSearch);
favoriteDatabase= Room.databaseBuilder(getActivity(),FavoriteDatabase.class,"myfavdb").
allowMainThreadQueries().build();

recyclerView = view.findViewById(R.id.recyclerview);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
final String country = getCountry();
retrieveJson("", country, API_Key);
btnSearch.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (!etQuery.getText().toString().equals("")) {
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
retrieveJson(etQuery.getText().toString(), country, API_Key);
}
});
retrieveJson(etQuery.getText().toString(), country, API_Key);
} else {
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
retrieveJson("", country, API_Key);
}
});
retrieveJson("", country, API_Key);
}
}
});
return view;
}
private void showChangeLanguageDialog() {
}
public void retrieveJson(String query, String country, String apiKey) {
swipeRefreshLayout.setRefreshing(true);
Call<Headlines> call;
if (!etQuery.getText().toString().equals("")) {
call = ApiClient.getInstance().getApi().getSpecifiedData(query, apiKey);
} else {
call = ApiClient.getInstance().getApi().getHeadLines(country, apiKey);
}

call.enqueue(new Callback<Headlines>() {
@Override
public void onResponse(Call<Headlines> call, Response<Headlines> response) {
if (response.isSuccessful() && response.body().getArticles() != null) {
swipeRefreshLayout.setRefreshing(false);
// articles.clear();
articles = response.body().getArticles();
adapter = new Adapter(getContext(), articles);
recyclerView.setAdapter(adapter);
}
}
@Override
public void onFailure(Call<Headlines> call, Throwable t) {
swipeRefreshLayout.setRefreshing(false);
Toast.makeText(getContext(), t.getLocalizedMessage(), Toast.LENGTH_SHORT).show();
}
});
}
public String getCountry() {
Locale locale = Locale.getDefault();
String country = locale.getCountry();
return country.toLowerCase();

}
}

适配器：

public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
Context context;
List<Articles> articles;
public Adapter(Context context, List<Articles> articles) {
this.context = context;
this.articles = articles;
}
@NonNull
@Override
public Adapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull final Adapter.ViewHolder holder, final int position) {
final Articles a = articles.get(position);
String imageUrl = a.getUrlToImage();
String url = a.getUrl();
holder.tvTitle.setText(a.getTitle());
Picasso.get().load(imageUrl).into(holder.imageView);

holder.tvSource.setText(a.getSource().getName());
holder.tvDate.setText(dateTime(a.getPublishedAt()));
holder.cardView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(context,DetailedActivity.class);
intent.putExtra("title",a.getTitle());
intent.putExtra("source",a.getSource().getName());
intent.putExtra("time",dateTime(a.getPublishedAt()));
intent.putExtra("desc",a.getDescription());
intent.putExtra("imageUrl",a.getUrlToImage());
intent.putExtra("url",a.getUrl());
context.startActivity(intent);
}
});
if (news.favoriteDatabase.favoriteDao().isFavorite(articles.get(position).getId())==1)
holder.bookmark.setImageResource(R.drawable.ic_bookmark);
else
holder.bookmark.setImageResource(R.drawable.ic_baseline_bookmark_border_24);

holder.bookmark.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
FavoriteList favoriteList = new FavoriteList();
int id = articles.get(position).getId();
String source = articles.get(position).getSource().getName();
String author = articles.get(position).getAuthor();
String publishedAt = articles.get(position).getPublishedAt();
String description = articles.get(position).getDescription();
String title = articles.get(position).getTitle();
String url = articles.get(position).getUrl();
String urlToImage = articles.get(position).getUrlToImage();
favoriteList.setId(id);
favoriteList.setAuthor(author);
favoriteList.setDescription(description);
favoriteList.setSource(source);
favoriteList.setPublishedAt(publishedAt);
favoriteList.setTitle(title);
favoriteList.setUrl(url);
favoriteList.setUrlToImage(urlToImage);
favoriteList.setPublishedAt(dateTime(articles.get(position).getPublishedAt()));
if (news.favoriteDatabase.favoriteDao().isFavorite(id)!=1){
holder.bookmark.setImageResource(R.drawable.ic_bookmark);
news.favoriteDatabase.favoriteDao().addData(favoriteList);
}else {    
holder.bookmark.setImageResource(R.drawable.ic_baseline_bookmark_border_24);
news.favoriteDatabase.favoriteDao().delete(favoriteList);
}
}
});
}
@Override
public int getItemCount() {
return articles.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
TextView tvTitle, tvSource, tvDate;
ImageView imageView;
ImageButton bookmark;
CardView cardView;
public ViewHolder(@NonNull View itemView) {
super(itemView);
tvTitle = itemView.findViewById(R.id.tvId);
tvSource = itemView.findViewById(R.id.tvSource);
tvDate = itemView.findViewById(R.id.tvDate);
imageView = itemView.findViewById(R.id.image);
cardView = itemView.findViewById(R.id.cardView);
bookmark = itemView.findViewById(R.id.favrr);
}
}

Answer 1

调试步骤：

1. 添加2-3个项目作为Favs
2. 重新启动应用程序。重新启动应用程序后，检查是否将这些项目显示为收藏夹

还将日志添加到那些您正在更改可绘制内容的if条件中。

看了你的JSON之后，看起来id就是造成问题的原因。所有json项的Id都为null，所以当fav时。一个显示fav。所有人。

解决方案：使用另一个字段检查数据是否添加到收藏夹列表

删除也不起作用尝试

@Query("DELETE FROM favoritelist WHERE title = :title")
void deleteByUserId(String title);

删除项目

此外https://github.com/amitshekhariitbhu/Android-Debug-Database

检查此库以调试数据库