我尝试使用picasso库将URL加载到imageView,但我无法让context
正确使用picasso库。
public class FeedAdapter extends RecyclerView.Adapter<FeedAdapter.ViewHolder> {
private List<Post> mDataset;
// Provide a reference to the views for each data item
// Complex data items may need more than one view per item, and
// you provide access to all the views for a data item in a view holder
public class ViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public TextView txtHeader;
public ImageView pub_image;
public ViewHolder(View v) {
super(v);
txtHeader = (TextView) v.findViewById(R.id.firstline);
pub_image = (ImageView) v.findViewById(R.id.imageView);
}
}
// Provide a suitable constructor (depends on the kind of dataset)
public FeedAdapter(List<Post> myDataset) {
mDataset = myDataset;
}
// Create new views (invoked by the layout manager)
@Override
public FeedAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
// create a new view
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.feedholder, parent, false);
// set the view's size, margins, paddings and layout parameters
ViewHolder vh = new ViewHolder(v);
return vh;
}
// Replace the contents of a view (invoked by the layout manager)
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
// - get element from your dataset at this position
// - replace the contents of the view with that element
holder.txtHeader.setText(mDataset.get(position).getPost_text());
Picasso.with(this.context).load("http://i.imgur.com/DvpvklR.png").into(holder.pub_image);
}
// Return the size of your dataset (invoked by the layout manager)
@Override
public int getItemCount() {
return mDataset.size();
}
}
答案 0 :(得分:210)
你有几个选择:
Context
作为参数传递给FeedAdapter并将其保留为类字段Context
。我强烈建议阅读它。有一个很好的工具 - Square {/ 3> Dagger
从任何View
对象获取它。在您的情况下,这可能适合您:
holder.pub_image.getContext()
由于pub_image
是ImageView
。
答案 1 :(得分:24)
您可以添加全局变量:
private Context context;
然后从这里分配上下文:
@Override
public FeedAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,int viewType) {
// create a new view
View v=LayoutInflater.from(parent.getContext()).inflate(R.layout.feedholder, parent, false);
// set the view's size, margins, paddings and layout parameters
ViewHolder vh = new ViewHolder(v);
// set the Context here
context = parent.getContext();
return vh;
}
Happy Codding :)
答案 2 :(得分:15)
您可以使用pub_image上下文(holder.pub_image.getContext()
):
@Override
public void onBindViewHolder(ViewHolder ViewHolder, int position) {
holder.txtHeader.setText(mDataset.get(position).getPost_text());
Picasso.with(holder.pub_image.getContext()).load("http://i.imgur.com/DvpvklR.png").into(holder.pub_image);
}
答案 3 :(得分:10)
简短回答:
Context context;
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
context = recyclerView.getContext();
}
解释为什么其他答案不是很好:
Context
传递给适配器是完全没必要的,因为RecyclerView
您可以从课程内部访问Context
级别获取ViewHolder
意味着您每次绑定或创建ViewHolder
时都会这样做。你复制了操作。Activity
寿命之外徘徊(这可能很奇怪),那么您已经有泄漏。答案 4 :(得分:5)
首先全球宣布
Context mContext;
通过构造函数传递上下文,通过修改它。
public FeedAdapter(List<Post> myDataset, Context context) {
mDataset = myDataset;
this.mContext = context;
}
然后在需要的时候使用mContext
答案 5 :(得分:4)
创建FeedAdapter的构造函数:
Context context; //global
public FeedAdapter(Context context)
{
this.context = context;
}
和活动
FeedAdapter obj = new FeedAdapter(this);
答案 6 :(得分:4)
您可以像这样使用 view.getContext()
示例强>
holder.tv_room_name.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(v.getContext(), "", Toast.LENGTH_SHORT).show();
}
});
答案 7 :(得分:2)
首先添加一个全局变量
Context mContext;
然后将构造函数更改为此
public FeedAdapter(Context context, List<Post> myDataset) {
mContext = context;
mDataset = myDataset;
}
创建适配器时传递上下文。
FeedAdapter myAdapter = new FeedAdapter(this,myDataset);
答案 8 :(得分:2)
你可以用这个:
itemView.getContext()
答案 9 :(得分:2)
您可以定义:
Context ctx;
然后在onCreate
上将ctx
初始化为:
ctx=parent.getContext();
注意:父级是一个ViewGroup。
答案 10 :(得分:1)
View mView;
mView.getContext();
答案 11 :(得分:0)
如果在布局上使用数据绑定,则可以从context
获得holder
。下面的例子。
@Override
public void onBindViewHolder(@NonNull GenericViewHolder holder, int position) {
View currentView = holder.binding.getRoot().findViewById(R.id.cycle_count_manage_location_line_layout);// id of your root layout
currentView.setBackgroundColor(ContextCompat.getColor(holder.binding.getRoot().getContext(), R.color.light_green));
}