Question

我正试图在我的RecyclerView CardView中实施类似谷歌加动画。我的onBindViewHolder方法出错了。

错误无法解析符号lastPosition，无法解决符号position这两个错误。

这是我的onBindViewHolder方法代码：

public class SimpleCardViewAdapter extends  RecyclerView.Adapter<SimpleCardViewAdapter.ViewHolder> {





private List<CardViewData> mDataset;

public SimpleCardViewAdapter(List<CardViewData> dataset) {
    mDataset = dataset;
}

@Override
public ViewHolder onCreateViewHolder(final ViewGroup viewGroup, int i) {
    View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.primary_layout, viewGroup, false);
    return new ViewHolder(v);
}

@Override
public void onBindViewHolder(final ViewHolder viewHolder, int i) {
    final CardViewData cardViewData = mDataset.get(i);

    viewHolder.mTitle.setText(cardViewData.getTitle());
    viewHolder.mDescription.setText(cardViewData.getDescription());
    viewHolder.mImage.setImageResource(cardViewData.getImage());

    Animation animation = AnimationUtils.loadAnimation(context,
            (i > lastPosition) ? R.anim.up_from_bottom
                    : R.anim.down_from_top);
    viewHolder.itemView.startAnimation(animation);
    lastPosition = i;
    viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast.makeText(v.getContext(), "Title: " + cardViewData.getTitle(), Toast.LENGTH_SHORT).show();
        }
    });


}

@Override
public int getItemCount() {
    return mDataset == null ? 0 : mDataset.size();

}

public static class ViewHolder extends RecyclerView.ViewHolder {

    public TextView mTitle;
    public TextView mDescription;
    public ImageView mImage;

    public ViewHolder(View itemView) {
        super(itemView);

        mTitle = (TextView) itemView.findViewById(R.id.row_title);
        mDescription = (TextView) itemView.findViewById(R.id.row_description);
        mImage = (ImageView) itemView.findViewById(R.id.row_image);
    }
}


}

Answer 1

public void onBindViewHolder(final ViewHolder viewHolder, int i) {
    final CardViewData cardViewData = mDataset.get(i);

    viewHolder.mTitle.setText(cardViewData.getTitle());
    viewHolder.mDescription.setText(cardViewData.getDescription());
    viewHolder.mImage.setImageResource(cardViewData.getImage());
    Animation animation = AnimationUtils.loadAnimation(context,
            (i > lastPosition) ? R.anim.up_from_bottom
                    : R.anim.down_from_top);
    viewHolder.itemView.startAnimation(animation);
    lastPosition = i;

    viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast.makeText(v.getContext(), "Title: " + cardViewData.getTitle(), Toast.LENGTH_SHORT).show();
        }
    });


}

Answer 2

更改构造函数以将Context传递给适配器。它将使用context解决您的问题。初始化适配器时，请调用getActivity()作为Context的参数。

我在lastPosition中没有看到任何逻辑，默认变量应该是什么，所以我只能声明并初始化这个变量。

private List<CardViewData> mDataset;
private int lastPosition = 0;
private Context context;

public SimpleCardViewAdapter(Context context, List<CardViewData> dataset) {
    mDataset = dataset;
    this.context = context;
}

Answer 3

如果这是您的完整代码，难怪为什么它说无法解析符号＆＃39; lastPosition＆＃39; 。

首先在类的开头初始化变量，如下面的

public class SimpleCardViewAdapter extends  RecyclerView.Adapter<SimpleCardViewAdapter.ViewHolder> {

int lastPosition = 0 ; // Here is the initialization

private List<CardViewData> mDataset;
public SimpleCardViewAdapter(List<CardViewData> dataset) {

    // your code here 

}
}

我认为你从某个地方复制粘贴代码。如果是这样，请提供您复制的链接，以便我们可以轻松地帮助您。

您的另一个错误无法解析符号＆＃39; 是不可能的。你确定你收到了这个错误吗？

在我的recyclerview适配器中的onBindViewHolder中出错

3 个答案: