更新 #1
添加了 hasStableIds(true) 并将 Picasso 更新到 2.5.2 版本。 它并没有解决问题。
复现:
使用 GridLayoutManager 的 RecyclerView(spanCount = 3)。 列表项是带有 ImageView 的 CardView。
当所有项都不适合屏幕时,在一个项上调用 notifyItemChanged 会导致 onBindViewHolder() 调用多次。 一次是由于 notifyItemChanged 提供的位置,其他调用是由于屏幕上不可见的项。
问题:
有时传递给 notifyItemChanged 的位置的项会加载属于不在屏幕上的项的图像(很可能是由于视图持有者的回收 - 尽管我会假设如果该项保持不变,则传递的视图持有者将是相同的)。
我在这里找到了 Jake 对其他问题的评论,他提到即使文件/URI 为空也要调用 load()。这里的每个 onBindViewHolder 都加载图像。
简单示例应用程序:
git clone https://github.com/gswierczynski/recycler-view-grid-layout-with-picasso.git
点击某个项目会调用notifyItemChanged方法,该方法的参数为该项目的位置。
代码:
public class MainActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
RecyclerView rv = (RecyclerView) rootView.findViewById(R.id.rv);
rv.setLayoutManager(new GridLayoutManager(getActivity(), 3));
rv.setItemAnimator(new DefaultItemAnimator());
rv.setAdapter(new ImageAdapter());
return rootView;
}
}
private static class ImageAdapter extends RecyclerView.Adapter<ImageViewHolder> implements ClickableViewHolder.OnClickListener {
public static final String TAG = "ImageAdapter";
List<Integer> resourceIds = Arrays.asList(
R.drawable.a0,
R.drawable.a1,
R.drawable.a2,
R.drawable.a3,
R.drawable.a4,
R.drawable.a5,
R.drawable.a6,
R.drawable.a7,
R.drawable.a8,
R.drawable.a9,
R.drawable.a10,
R.drawable.a11,
R.drawable.a12,
R.drawable.a13,
R.drawable.a14,
R.drawable.a15,
R.drawable.a16,
R.drawable.a17,
R.drawable.a18,
R.drawable.a19,
R.drawable.a20);
@Override
public ImageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item, parent, false);
return new ImageViewHolder(v, this);
}
@Override
public void onBindViewHolder(ImageViewHolder holder, int position) {
Log.d(TAG, "onBindViewHolder position: " + position + " | holder obj:" + holder.toString());
Picasso.with(holder.iv.getContext())
.load(resourceIds.get(position))
.fit()
.centerInside()
.into(holder.iv);
}
@Override
public int getItemCount() {
return resourceIds.size();
}
@Override
public void onClick(View view, int position) {
Log.d(TAG, "onClick position: " + position);
notifyItemChanged(position);
}
@Override
public boolean onLongClick(View view, int position) {
return false;
}
}
private static class ImageViewHolder extends ClickableViewHolder {
public ImageView iv;
public ImageViewHolder(View itemView, OnClickListener onClickListener) {
super(itemView, onClickListener);
iv = (ImageView) itemView.findViewById(R.id.iv);
}
}
}
public class ClickableViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener {
OnClickListener onClickListener;
public ClickableViewHolder(View itemView, OnClickListener onClickListener) {
super(itemView);
this.onClickListener = onClickListener;
itemView.setOnClickListener(this);
itemView.setOnLongClickListener(this);
}
@Override
public void onClick(View view) {
onClickListener.onClick(view, getPosition());
}
@Override
public boolean onLongClick(View view) {
return onClickListener.onLongClick(view, getPosition());
}
public static interface OnClickListener {
void onClick(View view, int position);
boolean onLongClick(View view, int position);
}
}