Question

我有各种位置名称，它们的经纬度来自服务器端。我使用自定义适配器将它们放在列表视图中。在适配器中，我编写了代码来计算位置与当前位置的距离。每件事都很好，但我想按距离排序。我无法弄清楚如何去做。

我的活动代码是：

    List<String> Names = new ArrayList<String>();
    List<String> MinLevel = new ArrayList<String>();

    Names=db.getId();
    MinLevel=db.getMinLevel();

    MapAdapter ad=new MapAdapter(this, Names,MinLevel);
    lv.setAdapter(ad);

MapAdapter

private final Context context;
private List<String>Name=new ArrayList<String>();
private List<String>Min=new ArrayList<String>();
PharmacyDB db;
public MapAdapter(Context context,List<String>phname,List<String>phmin) {
    super();
    this.context = context;

    this.Name=phname;
    this.Min=phmin;

}

@Override
public View getView(final int position, View convertView, ViewGroup parent) {


    LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    View v = inflater.inflate(R.layout.test_adapter,parent, false);
    db=new PharmacyDB(context);
    final TextView pharname = (TextView)v.findViewById(R.id.test_ad_name);
    final TextView distance = (TextView)v.findViewById(R.id.test_ad_dist);
    final TextView rad_min = (TextView)v.findViewById(R.id.test_rad);
    final RelativeLayout det=(RelativeLayout)v.findViewById(R.id.details);



    pharname.setText(db.getPharmacyName(Name.get(position)));
  if(!Min.get(position).equals("null")&&!Min.get(position).equals(null)){
      rad_min.setText(Min.get(position));
  }
  else{
      rad_min.setText("NA");
  }
  if(!db.getLat(Name.get(position)).equals("") && !db.getLat(Name.get(position)).contains("null") && !db.getLat(Name.get(position)).equals(null)&&!db.getLat(Name.get(position)).startsWith("0")){
  float dis= distFrom((float)MapTest.mLatitude, (float)MapTest.mLongitude, Float.parseFloat(db.getLat(Name.get(position))), Float.parseFloat(db.getLong(Name.get(position))));
  int d=Math.round(dis);


  if(d<1000){
  distance.setText(String.valueOf(d)+ " Meters");
  }
  else{
      if((d/1000)<50)
      distance.setText(String.valueOf(d/1000)+ " Kms");
      else
          distance.setText("NA");
  }
    }
    else{
        distance.setText("NA");
    }


   return v;
}


@Override
public int getCount(){
    // TODO Auto-generated method stub
    return Name.size();
}

@Override
public Object getItem(int arg0) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public long getItemId(int arg0) {
    return 0;
}
public static float distFrom(float lat1, float lng1, float lat2, float lng2) {
    double earthRadius = 6371000; //meters
    double dLat = Math.toRadians(lat2-lat1);
    double dLng = Math.toRadians(lng2-lng1);
    double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
               Math.cos(Math.toRadians(lat1)) *   Math.cos(Math.toRadians(lat2)) *
               Math.sin(dLng/2) * Math.sin(dLng/2);
    double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
    float dist = (float) (earthRadius * c);

    return dist;
    }

Answer 1

我建议您不要计算适配器中的距离为所有场创建一个简单的bean类，并根据距离实现Comparator or Comparable和覆盖CompareTo()方法。

创建该对象的列表，然后调用list.sort();

您将获得排序列表然后将此列表传递给适配器

按位置按Android排序地点

1 个答案: