Question

我想在我的应用程序中将Listview转换为RecyclerView，我尝试转换代码，但停留在getView方法上，谁能解释如何在Recylcer视图中使用此getView代码。

用于ListView的适配器 CardAdapter.java

public class CardAdapter extends ArrayAdapter<CardDataModel> {

    private Context context;
    List<CardDataModel> cards;
    SharedPreference sharedPreference;

    public CardAdapter(Context context, List<CardDataModel> cards) {
        super(context, R.layout.card_list_item, cards);
        this.context = context;
        this.cards = cards;
        sharedPreference = new SharedPreference();
    }

    private class ViewHolder {
        TextView CardNameTxt;
        TextView CardDescTxt;
        TextView CardPriceTxt;
        ImageView favoriteImg;
    }

    @Override
    public int getCount() {
        return cards.size();
    }

    @Override
    public CardDataModel getItem(int position) {
        return cards.get(position);
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        if (convertView == null) {
            LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.card_list_item, null);
            holder = new ViewHolder();
            holder.CardNameTxt = (TextView) convertView
                    .findViewById(R.id.txt_crd_name);
            holder.CardDescTxt = (TextView) convertView
                    .findViewById(R.id.txt_crd_desc);
            holder.CardPriceTxt = (TextView) convertView
                    .findViewById(R.id.txt_crd_no);
            holder.favoriteImg = (ImageView) convertView
                    .findViewById(R.id.imgbtn_favorite);

            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }
        CardDataModel card = (CardDataModel) getItem(position);
        holder.CardNameTxt.setText(card.getName());
        holder.CardDescTxt.setText(card.getDescription());
        holder.CardPriceTxt.setText(card.getPrice() + " ");

        /*If a product exists in shared preferences then set heart_red drawable
         * and set a tag*/
        if (checkFavoriteItem(card)) {
            holder.favoriteImg.setImageResource(R.drawable.heart_red);
            holder.favoriteImg.setTag("red");
        } else {
            holder.favoriteImg.setImageResource(R.drawable.heart_grey);
            holder.favoriteImg.setTag("grey");
        }

        return convertView;
    }




    public boolean checkFavoriteItem(CardDataModel checkCard) {
        boolean check = false;
        List<CardDataModel> favorites = sharedPreference.getFavorites(context);
        if (favorites != null) {
            for (CardDataModel card : favorites) {
                if (card.equals(checkCard)) {
                    check = true;
                    break;
                }
            }
        }
        return check;
    }

    @Override
    public void add(CardDataModel card) {
        super.add(card);
        cards.add(card);
        notifyDataSetChanged();
    }

    @Override
    public void remove(CardDataModel card) {
        super.remove(card);
        cards.remove(card);
        notifyDataSetChanged();
    }
}

在RecyclerView Adapter中转换了这样的代码... CardRvAdapter.java

public class CardRvAdapter extends RecyclerView.Adapter<CardRvAdapter.MyViewHolder> {


    private Context context;
    List<CardDataModel> cards;
    SharedPreference sharedPreference;

    public CardRvAdapter(Context context, List<CardDataModel> cards) {

        this.context = context;
        this.cards = cards;
        sharedPreference = new SharedPreference(); }

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

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

        // on create view holder code
        View view;
        LayoutInflater mInflater = LayoutInflater.from(context);
        view  = mInflater.inflate(R.layout.card_list_item, viewGroup,false);
        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder myViewHolder, int i) {

        //on bind view holder code
        myViewHolder.CardPriceTxt.setText(cards.get(i).getPrice());
        myViewHolder.CardNameTxt.setText(cards.get(i).getName());
        myViewHolder.CardDescTxt.setText(cards.get(i).getDescription());

        if (checkFavoriteItem(card)) {
           myViewHolder.favoriteImg.setImageResource(R.drawable.heart_red);
            myViewHolder.favoriteImg.setTag("red");
        } else {
            myViewHolder.favoriteImg.setImageResource(R.drawable.heart_grey);
            myViewHolder.favoriteImg.setTag("grey");
        } }

        // checking for favotites in shared preferences

        public boolean checkFavoriteItem(CardDataModel checkCard) {
        boolean check = false;
        List<CardDataModel> favorites = sharedPreference.getFavorites(context);
        if (favorites != null) {
            for (CardDataModel card : favorites) {
                if (card.equals(checkCard)) {
                    check = true;
                    break;
                }
            }
        }
        return check;
    }

    @Override
    public void add(CardDataModel card) {
        super.add(card);
        cards.add(card);
        notifyDataSetChanged();
    }

    @Override
    public void remove(CardDataModel card) {
        super.remove(card);
        cards.remove(card);
        notifyDataSetChanged();
    }


    public class MyViewHolder extends RecyclerView.ViewHolder {
        TextView CardNameTxt;
        TextView CardDescTxt;
        TextView CardPriceTxt;
        ImageView favoriteImg;

        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            this.CardDescTxt = (TextView) itemView.findViewById(R.id.txt_crd_desc);
            this.CardNameTxt = (TextView) itemView.findViewById(R.id.txt_crd_name);
            this.CardPriceTxt = (TextView) itemView.findViewById(R.id.txt_crd_no);
            this.favoriteImg = (ImageView) itemView.findViewById(R.id.imgbtn_favorite);
            }}}

问题部分。

 public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        if (convertView == null) {
            LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.card_list_item, null);
            holder = new ViewHolder();
            holder.CardNameTxt = (TextView) convertView
                    .findViewById(R.id.txt_crd_name);
            holder.CardDescTxt = (TextView) convertView
                    .findViewById(R.id.txt_crd_desc);
            holder.CardPriceTxt = (TextView) convertView
                    .findViewById(R.id.txt_crd_no);
            holder.favoriteImg = (ImageView) convertView
                    .findViewById(R.id.imgbtn_favorite);

            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }
        CardDataModel card = (CardDataModel) getItem(position);
        holder.CardNameTxt.setText(card.getName());
        holder.CardDescTxt.setText(card.getDescription());
        holder.CardPriceTxt.setText(card.getPrice() + " ");

        /*If a product exists in shared preferences then set heart_red drawable
         * and set a tag*/
        if (checkFavoriteItem(card)) {
            holder.favoriteImg.setImageResource(R.drawable.heart_red);
            holder.favoriteImg.setTag("red");
        } else {
            holder.favoriteImg.setImageResource(R.drawable.heart_grey);
            holder.favoriteImg.setTag("grey");
        }

        return convertView;
    }

如何修改此代码以及在何处添加此checkFavItem，添加和删除方法。.建议我，我是android开发的新手。

Answer 1

完成RecyclerView代码

// specify the row layout file and click for each row
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(listItemLayout, parent, false);
    ViewHolder myViewHolder = new ViewHolder(view);
    return myViewHolder;
}

// load data in each row element
@Override
public void onBindViewHolder(final ViewHolder holder, final int listPosition) {
    TextView item = holder.item;
    item.setText(itemList.get(listPosition).getName());
}

ListView到RecyclerView的转换，转换get View方法时出现问题

1 个答案: