android - 为 Imageview 请求 RecyclerViewAdapter.notifyItemChanged 的​​示例

Question

我想使用我的 Recyclerviews 中的一个按钮来更改 Recyclerview 中的一个对象，即将 Imageview 设置为透明。

所以我发现我需要在那个场合使用 notifyItemChanged(int,object,payload) 看到这个线程：（示例 NotifyItemChanged）。遗憾的是，这个例子没有达到关于如何使用对象值来改变图像的值，(ImageView.setImageAlpha(70))。

要求：

您能否给我一个示例，说明如何使用 notifyItemChanged 更改 Recycleradapter 中 ImageView之一的 setImageAlpha 值。

我的框架

我将发布我的代码，因此如果您愿意，可以相应地对其进行编辑。但我也可以尝试自己做。

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


    private List<Cards> mData;
    private List<Heros> mHero, mHeroAdd;
    private List<Spells> mSpell, mSpellSig;
    private List<Items> mItem;
    private List<Improvements> mImpr, mImprSig;
    private List<Creeps> mCreep, mCreepSig;
    private List<Decklist> mDecklist;
    private List<Decklist_Heros> mDecklistHeros;
    DBHelper dbHelper;

    private CardView introCardview;
    private Context mContext;
    private RecyclerView mrvList,mrvHeros;
    private deckbuilder_RViewAdapter_List mRViewAdapterList;
    private deckbuilder_RViewAdapter_Heros mRViewAdapterHeros;

    private int questionmarkNo;

    public deckbuilder_RViewAdapter_Card (FragmentActivity mContext, List<Cards> mData, deckbuilder_RViewAdapter_List mRViewAdapterList, List<Decklist> mDecklist, RecyclerView rvList, deckbuilder_RViewAdapter_Heros mRViewAdapterHeros, List<Decklist_Heros> mDecklistHeros, RecyclerView rvHeros) {
        this.mData = mData;
        this.mContext = mContext;
        this.mRViewAdapterList = mRViewAdapterList;
        this.mDecklist = mDecklist;
        this.mrvList = rvList;
        this.mRViewAdapterHeros = mRViewAdapterHeros;
        this.mDecklistHeros = mDecklistHeros;
        this.mrvHeros= rvHeros;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {

        dbHelper = new DBHelper(mContext.getApplicationContext());
        dbHelper.createDataBase();// used for clickable

        //Todo change inflated layout later on <-????
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.layout_cardview_deckbuilder_cards, viewGroup, false);
        return new deckbuilder_RViewAdapter_Card.ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull final ViewHolder viewHolder, final int position) {
        viewHolder.ivCardImage.setImageResource(mData.get(position).getCardImage());
        viewHolder.tvCardName.setText(mData.get(position).getCardName());
        viewHolder.ivCardImage.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                cardClickable(position);
            }
        });
        viewHolder.tvCardName.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                cardClickable(position);
            }
        });

        /* Init the Add and Remove button */
        viewHolder.civ_deckbuilder_add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(mData.get(position).getCardType().equals("hero")){
                    addHero(viewHolder, position);

                }else {
                    addOtherCards(viewHolder,position);
                }
            }
        });

        viewHolder.civ_deckbuilder_remove.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(mData.get(position).getCardType().equals("hero")){
                    removeHero(position);
                    **viewHolder.ivCardImage.setImageAlpha(70);**
                }else {
                    removeOtherCard(position);
                    **viewHolder.ivCardImage.setImageAlpha(70);**
                }
            }
        });
    }

    @Override
    public int getItemCount() {
        return mData.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder{
        CircleImageView civ_deckbuilder_add, civ_deckbuilder_remove, civ_deckbuilder_number;
        ImageView ivCardImage;
        TextView tvCardName;

        public ViewHolder(@NonNull View introListView) {
            super(introListView);
            ivCardImage = introListView.findViewById(R.id.ivDeckbuilder_img);
            tvCardName = introListView.findViewById(R.id.tvDeckbuilder_title);
            civ_deckbuilder_add = introListView.findViewById(R.id.civ_deckbuilder_add);
            civ_deckbuilder_remove = introListView.findViewById(R.id.civ_deckbuilder_remove);
        }
    }

    //[...] used methods should not be relevant.

}

感谢您为我提供的任何帮助！

标签： androidandroid-studioobjectandroid-recyclerview

Answer 1

1. 首先，您的Cards数据类应该有一个初始化为 255的alpha属性以获得完全可见的图像。

2. 在 onBindViewHolder 中使用

   viewHolder.ivCardImage.setImageAlpha(mData.get(position).getAlpha());

3. 然后在你的点击事件中

   @Override public void onClick(View view) { .... mData.get(position).setAlpha(70); notifyItemChanged(position); } }