java如何在单击项时更改列表项的外观。

Question

在我的应用程序中，我有水平列表视图。在“项目选择”中，我想更改选定项目的背景颜色及其文本视图颜色。我已经猜出了那部分。但如何重置先前选定项目的背景色和文本视图颜色。这是我的适配器类

public class DateRangeListViewAdapter extends RecyclerView.Adapter<DateRangeListViewAdapter.ContentViewHolder>  {

private ItemClickListener itemClickListener;
private LayoutInflater inflater;
private ArrayList<String> data;
private Context context;
private int dataType;
private int previousSelectedPosition;
private static final int DATE_TYPE = 1;
private static final int STATUS_TYPE = 2;

public DateRangeListViewAdapter(ArrayList<String> data, Context context,int dataType) {
    this.data = data;
    this.context = context;
    this.dataType = dataType;
    inflater  = LayoutInflater.from(context);
    previousSelectedPosition = -1;
}

public void setItemClickListener(ItemClickListener itemClickListener) {
    this.itemClickListener = itemClickListener;
}

@Override
public ContentViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = inflater.inflate(R.layout.custom_date_range_list_item,parent,false);
    return new ContentViewHolder(view);
}

@Override
public void onBindViewHolder(ContentViewHolder holder, int position) {
    String name = data.get(position);
    holder.dateText.setText(name);
}

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


public class ContentViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    private FrameLayout main;
    private TextView dateText;

    public ContentViewHolder(View itemView) {
        super(itemView);
        itemView.setOnClickListener(this);
        main = (FrameLayout) itemView.findViewById(R.id.main_layout);
        dateText = (TextView) itemView.findViewById(R.id.date_name);
    }

    @Override
    public void onClick(View v) {

        //Selected item color change
        main.setBackground(ContextCompat.getDrawable(context,R.drawable.date_range_selected_item_background));
        dateText.setTextColor(ContextCompat.getColor(context,R.color.colorPrimary));

        if(itemClickListener!=null){
            itemClickListener.onItemClick(v,this.getLayoutPosition(),dataType,getOldPosition());
        }
    }
}

public interface ItemClickListener{
    public void onItemClick(View v, int position,int dataType,int oldPosition);
    }
}

Answer 1

你的OnClickListener工作不完美。您只需要从“ItemClickListener”界面实现ViewHolder。并在onCreateViewHolder中添加这一行：

View view = inflater.inflate(R.layout.custom_date_range_list_item,parent,false);
ContentViewHolder cVh =  ContentViewHolder(view);view.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            cVh.onItemClick(v,this.getLayoutPosition(),cVh .dataType,cVh .getOldPosition());

        }
    });return cVh

Answer 2

基本上，您希望充分利用int标志previousSelectedPosition，跟踪单击的列表项的位置，调用notifyDataSetChanged()，然后将该标志设置为onBindViewHolder()内条件语句的一部分，以便在视图持有者的视图不断绑定时相应地更新视图持有者的视图。尝试以下更改：

视图持有者的onClick（）：

@Override
public void onClick(View v) {
    if (itemClickListener!=null) {
        previousSelectedPosition = getAdapterPosition();

        notifyDataSetChanged();

        itemClickListener.onItemClick(v,this.getLayoutPosition(),dataType,getOldPosition());
    }
}

回收视图。适配器的onBindViewHolder（）：

@Override
public void onBindViewHolder(ContentViewHolder holder, int position) {
    String name = data.get(position);
    holder.dateText.setText(name);

    if (previousSelectedPosition == position) {
        main.setBackground(ContextCompat.getDrawable(context,R.drawable.date_range_selected_item_background));
        dateText.setTextColor(ContextCompat.getColor(context,R.color.colorPrimary));
    } else {
        // TODO: Configure the FrameLayout and TextView here for initial runtime as well as back to default
    }
}

。。。是的，请确保在初始运行时将previousSelectedPosition初始化为-1，这样onBindViewHolder()中的条件在标志更新之前（即在单击列表项之后）不会有任何影响