Question

我有桌面网站和收藏夹。我想将网站添加到收藏夹，当我点击recyclerView中的checkBox并从收藏夹中删除时，我第二次点击复选框。我认为这应该是多对多的关系。我创建了以下表格：

网站已

@Entity
public class WebSites {

  @PrimaryKey(autoGenerate = true)
  public int id;

  @ColumnInfo()
  public String website_head;

  public WebSites(@NonNull String website_head {
  this.website_head = website_head;
}

收藏夹

@Entity
public class Favorites {

  @PrimaryKey(autoGenerate = true)
  private int id;

}

FavoritesWithWebSites

@Entity(tableName = "favorites_with_websites",
   primaryKeys = { "websitesId", "favId"},
   foreignKeys = {
        @ForeignKey(entity = WebSites.class,
                    parentColumns = "id",
                    childColumns = "websitesId"),
        @ForeignKey(entity = Favorites.class,
                    parentColumns = "id",
                    childColumns = "favId")
    })
public class FavoritesWithWebSites  {

  public final int websitesId;
  public final int favId;

  public FavoritesWithWebSites(int websitesId, int favId) {
    this.websitesId = websitesId;
    this.favId = favId;
  }
}

来自道的询问：

 @Query("SELECT * FROM websites INNER JOIN favorites_with_websites ON " +
    "websites.id = favorites_with_websites.websitesId")
 LiveData<List<WebSites>> finGet();

我不明白在点击chkebox时我必须如何添加到收藏夹并从收藏夹中删除。当我添加数据时，我不明白我必须向FavoritesWithWebSites添加哪些参数。

我的适配器

public class MyRecViewAdapter extends 
RecyclerView.Adapter<MyRecViewAdapter.ViewHolder> {

  private final LayoutInflater mInflater;
  private List<WebSites> mWebSites; // Cached copy of words
  private Context context;

  private WebSitesViewModel webSitesViewModel;


  class ViewHolder extends RecyclerView.ViewHolder {

     private final TextView tvHead;
     private final TextView tvDesc;
     private final ImageView ivWebImage;
     private final CheckBox chbFavorites;


     private ViewHolder(View itemView) {
       super(itemView);

       tvHead = itemView.findViewById(R.id.tv_head);
       tvDesc = itemView.findViewById(R.id.tv_desc);
       ivWebImage = itemView.findViewById(R.id.ivWebImage);
       chbFavorites = itemView.findViewById(R.id.chbFavorites);

   }

  }

  public List<WebSites> getmWebSites() {
    return mWebSites;
  }

  public MyRecViewAdapter(Context context, WebSitesViewModel 
    webSitesViewModel) {
      this.context = context;
      mInflater = LayoutInflater.from(this.context);
      this.webSitesViewModel = webSitesViewModel;
  }

  @Override
  public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View itemView = mInflater.inflate(R.layout.list_item, parent, false);
    return new ViewHolder(itemView);
  }

  @Override
  public void onBindViewHolder(final ViewHolder holder, final int position) 
     {
       if (mWebSites != null) {
       final WebSites current = mWebSites.get(position);

       holder.tvHead.setText(current.getWebsite_head());
       holder.tvDesc.setText(current.getWebsite_url());
       holder.chbFavorites.setChecked(current.getSelected());

       holder.chbFavorites.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
             if (holder.chbFavorites.isChecked()) {

                //????????????????????
             }
             else {

                //??????????????

             }
         }
     });

     Picasso.with(context).load(current.getImg_src())
             .error(R.drawable.ic_launcher_foreground)
             .placeholder(R.drawable.ic_launcher_foreground)
             .into(holder.ivWebImage);

    } else {
      // Covers the case of data not being ready yet.
      holder.tvHead.setText("No Word");
      holder.tvDesc.setText("No Word");
  }
 }

 public void setWebSites(List<WebSites> webSites){
     mWebSites = webSites;
    notifyDataSetChanged();
 }


   // getItemCount() is called many times, and when it is first called,
  // mWords has not been updated (means initially, it's null, and we can't 
  return null).
  @Override
  public int getItemCount() {
  if (mWebSites != null)
     return mWebSites.size();
  else return 0;
 }


}

Answer 1

这不是M：M的关系。

您可以在网站中添加此字段：

@ColumnInfo(name = "is_fav")
private boolean isFavorite;

在你的适配器中使用它：

holder.chbFavorites.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View v) {
         boolean isFav = holder.chbFavorites.isChecked();
         current.setIsFavorite(isFav);
         yourWebsitesDao.update(current);
     }
 });

android房间很多很多，添加到收藏夹

1 个答案: