java - 如何更改项目单击时的列表项目外观。

Question

在我的应用程序中，我有水平 ListView 。在项目选择上，我想更改所选项目的背景颜色及其 TextView 颜色。我已经弄清楚了那部分。但是如何重置先前选定项目的背景颜色和 TextView 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

你基本上想充分利用你的 int 标志，previousSelectedPosition ，要跟踪单击的列表项的位置，请调用 notifyDataSetChanged() ，然后将该标志设置为 onBindViewHolder() 内的条件语句的一部分当 ViewHolder 的 View 不断被绑定(bind)时，相应地更新它们。尝试以下更改:

ViewHolder 的 onClick():

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

        notifyDataSetChanged();

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

RecyclerView.Adapter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，请务必保留 previousSelectedPosition初始运行时初始化为 -1，就像 onBindViewHolder() 中的条件一样直到标志更新(即单击列表项后)才重要。