java - 我有一个回收器 View ，onRun 将显示，但单击按钮后它将为空，我想设置默认回收器 View

Question

我目前有一个回收器 View ，可以在 Android studio 中使用纬度和经度。由于使用模拟器而加载时，我传递了一个默认位置，这会加载 map 中该位置周围的区域。我还有一个微调器，可以让您更改区域并在屏幕上的 map 上显示标记。但是问题是，当使用位置(在我的情况下是当前位置(设置为默认模拟器位置 Google Pixel San Francisco？)时，回收器 View 显示为空，我想在 Adapter 类中编辑我的回收器 View ，以便如果 View 为空，请将文本设置为“您周围没有地方”，如果需要代码，请询问。

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {

        QuietPlace quietPlace = mQuietPlace.get(position);
        if (mQuietPlace.size() > 0){
            TextView textView = holder.titleTextView;
        textView.setText(quietPlace.getName());
        TextView textView2 = holder.noiseTextView;
        textView2.setText(quietPlace.getNoise());
        TextView textView3 = holder.distanceTextView;
        textView3.setText(String.valueOf(quietPlace.getDistance()));
        }
        else {
            TextView textViewEmpty = holder.titleTextView;
            textViewEmpty.setText("No Quiet Places near your location");
            TextView textViewEmpty2 = holder.noiseTextView;
            textViewEmpty2.setText(" ");
            TextView textViewEmpty3 = holder.distanceTextView;
            textViewEmpty3.setText(" ");
        }
    }

编辑:

package com.example.myapplication;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

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

    private List<QuietPlace> mQuietPlace;

    public QuietPlaceAdapter(List<QuietPlace> quietPlaces)
    {
        mQuietPlace = quietPlaces;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        Context context = parent.getContext();
        LayoutInflater inflater = LayoutInflater.from(context);
        View quietPlaceView = inflater.inflate(R.layout.recycler_view, parent, false);
        ViewHolder viewHolder = new ViewHolder(quietPlaceView);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        QuietPlace quietPlace = mQuietPlace.get(position);

        TextView textView = holder.titleTextView;
        textView.setText(quietPlace.getName());
        TextView textView2 = holder.noiseTextView;
        textView2.setText(quietPlace.getNoise());
        TextView textView3 = holder.distanceTextView;
        textView3.setText(String.valueOf(quietPlace.getDistance()));
    }

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

    public class ViewHolder extends RecyclerView.ViewHolder {
        public TextView titleTextView;
        public TextView noiseTextView;
        public TextView distanceTextView;
        public ViewHolder(View itemView) {
            super(itemView);

            titleTextView = (TextView) itemView.findViewById(R.id.quietPlaceTitle);
            noiseTextView = (TextView) itemView.findViewById(R.id.quietPlaceNoise);
            distanceTextView = (TextView) itemView.findViewById(R.id.quietPlaceDistance);
        }
    }

}

Answer 1

如果列表是动态的，请勿在构造函数中传递列表。

在您的适配器中添加此功能

public void setPanelList(List<QuietPlace> quietPlaces){

    mQuietPlace = quietPlaces;
    notifyDataSetChanged();
}

在 Activity 中，当 quietPlaces 更改时 setPanelList(quietPlaces)。

quietPlaceAdapter.setPanelList(quietPlaces)

希望这有帮助。