毕加索 - 找不到"context"

Question

首先，我是一个初学者，这对你来说可能是一个愚蠢的问题。我需要将上下文传递给以下代码，以便在回收器视图中加载图像。尝试了几个选项，但任何一个都不成功。我的问题是如何找到要传入以下代码的上下文。

Picasso.with(context here).load("http://i.imgur.com/DvpvklR.png").into(thumbnail);

这是导致问题的完整代码(我正在尝试将图像传递给回收器视图(

public class WishListAdapter extends RecyclerView.Adapter<WishListAdapter.DerpHolder> {
    private List<WishListItem> listData;
    private LayoutInflater inflater;
    public WishListAdapter(List<WishListItem> listData, Context c) {
        inflater = LayoutInflater.from(c);
        this.listData = listData;
    }
    @Override
    public WishListAdapter.DerpHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = inflater.inflate(R.layout.wish_list_item, parent, false);
        return new DerpHolder(view);
    }
    @Override
    public void onBindViewHolder(DerpHolder holder, int position) {
    }
    public void setListData(ArrayList<WishListItem> exerciseList) {
        this.listData.clear();
        this.listData.addAll(exerciseList);
    }
    @Override
    public int getItemCount() {
        return listData.size();
    }
    class DerpHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        ImageView thumbnail;
        TextView title;
        TextView subTitle;
        View container;

        public DerpHolder(View itemView) {
            super(itemView);
            thumbnail = itemView.findViewById(R.id.im_item_icon);
            //subTitle = itemView.findViewById(R.id.lbl_item_sub_title);
            //title = itemView.findViewById(R.id.lbl_item_text);
            container = itemView.findViewById(R.id.cont_item_root);
            container.setOnClickListener(this);
            Picasso.with(context ).load("http://i.imgur.com/DvpvklR.png").into(thumbnail);
        }
        @Override
        public void onClick(View v) {
            Log.d("janitha", "item clicked");
        }

我也读过以下内容：-毕加索和背景

期待别人的帮助。

Answer 1

您尚未从构造函数中保存上下文。像这样做：

public class WishListAdapter extends 
     RecyclerView.Adapter<WishListAdapter.DerpHolder> {
    private List<WishListItem> listData;
    private LayoutInflater inflater;
    Context context;
    public WishListAdapter(List<WishListItem> listData, Context c) {
        inflater = LayoutInflater.from(c);
        this.listData = listData;
        this.context = c;
    }
    @Override
    public WishListAdapter.DerpHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = inflater.inflate(R.layout.wish_list_item, parent, false);
        return new DerpHolder(view);
    }
    @Override
    public void onBindViewHolder(DerpHolder holder, int position) {
    }
    public void setListData(ArrayList<WishListItem> exerciseList) {
        this.listData.clear();
        this.listData.addAll(exerciseList);
    }
    @Override
    public int getItemCount() {
        return listData.size();
    }
    class DerpHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        ImageView thumbnail;
        TextView title;
        TextView subTitle;
        View container;

        public DerpHolder(View itemView) {
            super(itemView);
            thumbnail = itemView.findViewById(R.id.im_item_icon);
            //subTitle = itemView.findViewById(R.id.lbl_item_sub_title);
            //title = itemView.findViewById(R.id.lbl_item_text);
            container = itemView.findViewById(R.id.cont_item_root);
            container.setOnClickListener(this);
            Picasso.with(context ).load("http://i.imgur.com/DvpvklR.png").into(thumbnail);
        }
        @Override
        public void onClick(View v) {
            Log.d("janitha", "item clicked");
        }

Answer 2

尝试，

private Context context;

在您的构造函数中，

this.context = c;

现在您可以使用"上下文"作为参数。

Answer 3

按如下方式修改代码：

private List<WishListItem> listData;
private LayoutInflater inflater;
private Context mContext;
public WishListAdapter(List<WishListItem> listData, Context c) {
    inflater = LayoutInflater.from(c);
    this.listData = listData;
    this.mContext = c;
}

然后mContext与毕加索一起使用：

Picasso.with(mContext).load("http://i.imgur.com/DvpvklR.png").into(thumbnail);

Answer 4

请像下面这样声明上下文变量并使用它：

public class WishListAdapter extends RecyclerView.Adapter<WishListAdapter.DerpHolder> {
    private List<WishListItem> listData;
    private LayoutInflater inflater;
    private Context context
    public WishListAdapter(List<WishListItem> listData, Context c) {
        inflater = LayoutInflater.from(c);
        this.listData = listData;
        this.context = c;
    }
    @Override
    public WishListAdapter.DerpHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = inflater.inflate(R.layout.wish_list_item, parent, false);
        return new DerpHolder(view);
    }
    @Override
    public void onBindViewHolder(DerpHolder holder, int position) {
    }
    public void setListData(ArrayList<WishListItem> exerciseList) {
        this.listData.clear();
        this.listData.addAll(exerciseList);
    }
    @Override
    public int getItemCount() {
        return listData.size();
    }
    class DerpHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        ImageView thumbnail;
        TextView title;
        TextView subTitle;
        View container;

        public DerpHolder(View itemView) {
            super(itemView);
            thumbnail = itemView.findViewById(R.id.im_item_icon);
            //subTitle = itemView.findViewById(R.id.lbl_item_sub_title);
            //title = itemView.findViewById(R.id.lbl_item_text);
            container = itemView.findViewById(R.id.cont_item_root);
            container.setOnClickListener(this);
            Picasso.with(context ).load("http://i.imgur.com/DvpvklR.png").into(thumbnail);
        }
        @Override
        public void onClick(View v) {
            Log.d("janitha", "item clicked");
        }