Question

我有一个具有recyclerview的应用程序。我想给用户一个机会，在夜间和白天模式主题之间切换。我知道如何更改文本颜色和背景颜色，但是在这种情况下我不能。实际上，我无法从MainActivity中找到项目布局变量。如何从MainActivity创建ViewHolder类的对象？谁能帮我吗？

这是我的适配器类：

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

    private List<ListItemModel> listItems;
    private Context context;

    public MyAdapter(List<ListItemModel> listItems, Context context) {
        this.listItems = listItems;
        this.context = context;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_model, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        final ListItemModel listItem = listItems.get(position);
        holder.index_number.setText(listItem.getIndexNumber());
        holder.title_name.setText(listItem.getTitle());

    }

    @Override
    public int getItemCount() {
        return listItems.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {

        TextView index_number, title_name;

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

            index_number = (TextView) itemView.findViewById(R.id.model_text_index_id);
            title_name = (TextView) itemView.findViewById(R.id.model_text_title_id);

        }

    }
}

Answer 1

如果是一个选择列表，则可以在列表中定义一个int参数，并在适配器中定义一个方法

....
private int selectedPosition = -1;

public void setSelectedPosition(int index){
  selectedPosition  = index;
  notifyItemChanged(selectedPosition)
}

然后在OnBindViewHolder中执行以下操作：

 @Override
public void onBindViewHolder(ViewHolder holder, int position) {
    final ListItemModel listItem = listItems.get(position);

    holder.index_number.setText(listItem.getIndexNumber());
    holder.title_name.setText(listItem.getTitle());

    if(position == selectedPosition){
      holder.index_number.setTextColor(MY_COLOR)
      holder.title_name.setTextColor(MY_COLOR)
    } else {
      holder.index_number.setTextColor(NORMAL_COLOR)
      holder.title_name.setTextColor(NORMAL_COLOR)
    }

}

对于多选列表，您可以在ListItemModel中定义一个像isChosen这样的参数，并将该参数更改为true和false，然后在OnBindViewHolder中检查该参数

Answer 2

i found the solution of your problem


create a method inside your activity and call when click on item in adapter and send position

    public void click(int position){

        TestAdapter.ViewHolder viewHolder = (TestAdapter.ViewHolder)recyclerView.findViewHolderForAdapterPosition(position);

        viewHolder.text_color .setTextColor(Color.parseColor("#245251"));


    }

hope this will help you.

如何从MainActivity更改RecyclerView项目的颜色？

2 个答案: