毕加索 - 找不到“上下文”答案

【问题标题】：Picasso - can't find "context"毕加索 - 找不到“上下文”
【发布时间】：2018-04-26 23:57:53
【问题描述】：

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 recyclerview 中加载图像。 尝试了几个选项，但其中任何一个都不成功。我的问题是如何找到要在以下代码中传递的上下文。

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 recyclerview）

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：-Picasso and context

期待别人的帮助。

【问题讨论】：

标签： java android android-recyclerview picasso android-context

【解决方案1】：

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");

        }

【讨论】：

【解决方案2】：

修改你的代码如下：

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;
}

然后将mContext 与毕加索一起使用：

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

【讨论】：

【解决方案3】：

试试，

private Context context;

在你的构造函数中，

this.context = c;

现在您可以使用“上下文”作为参数。

【讨论】：

【解决方案4】：

您尚未从构造函数中保存上下文。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");

        }

【讨论】：