【发布时间】：2016-04-25 05:01:46
【问题描述】：
我正在开发一个 android 应用程序，它将跟踪当前位置的纬度和经度并存储在外部数据库中。这里我有一个纬度和经度列表。我使用自定义适配器填充它们。但是，这里我需要从一个基本纬度和基本经度到剩余项目纬度和经度的距离。这里的基本纬度和经度是由用户自己选择的。下面的列表解释如下我有
SELECTION LAT LONG DISTANCE
-------------------------------------------------
checkbox1 123.4546 456.48751 Text
checkbox2 123.4546 456.48751 Text
checkbox3 123.4546 456.48751 Text
checkbox4 123.4546 456.48751 Text
如果用户选择复选框 1，那么我必须在 KILOMETERS 中找到从复选框 1 lat long 到复选框 2、复选框 3、check-box-4 lat long 的距离strong> 并展示在他们尊敬的位置上。 这是我编写的适配器中的一些代码，但没有显示任何结果。
public class Locations_Adapter extends BaseAdapter {
public String distance_string;
Context context;
List<Locations_modle> objects;
double distance, latitude, longitude;
String latitude_string, longitude_string;
double baseLat, baseLong, finalLat, finalLong;
Location location_pointa, location_pointb;
TextView distance_text;
float[] results;
int selectedPostion = -1;
public Locations_Adapter(Context context, int resource, List<Locations_modle> objects) {
this.context = context;
this.objects = objects;
}
/**
* Distance calculation between two lat longs
**/
private static double calculateDistance(double baseLat, double baseLong, double latitude, double longitude, String unit) {
double theta = baseLong - longitude;
double dist = Math.sin(deg2rad(baseLat)) * Math.sin(deg2rad(latitude)) + Math.cos(deg2rad(baseLat)) * Math.cos(deg2rad(longitude)) * Math.cos(deg2rad(theta));
dist = Math.acos(dist);
dist = rad2deg(dist);
dist = dist * 60 * 1.1515;
if (unit == "K") {
dist = dist * 1.609344;
} else if (unit == "N") {
dist = dist * 0.8684;
}
return (dist);
}
/*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
/*:: This function converts decimal degrees to radians :*/
/*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
private static double deg2rad(double deg) {
return (deg * Math.PI / 180.0);
}
/*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
/*:: This function converts radians to decimal degrees :*/
/*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
private static double rad2deg(double rad) {
return (rad * 180 / Math.PI);
}
@Override
public int getCount() {
return objects.size();
}
@Override
public Object getItem(int position) {
return objects.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(final int position, View convertView, final ViewGroup parent) {
final View locations_row = LayoutInflater.from(context).inflate(R.layout.layout_adapter_list_details, null);
final Locations_modle location = (Locations_modle) objects.get(position);
TextView text_cust_name = (TextView) locations_row.findViewById(R.id.txt_cust_name_heading);
TextView latitude = (TextView) locations_row.findViewById(R.id.txt_latitude);
latitude.setText(location.getLatitude());
TextView longitude = (TextView) locations_row.findViewById(R.id.txt_longitude);
distance_text = (TextView) locations_row.findViewById(R.id.txt_distance);
longitude.setText(location.getLongitude());
text_cust_name.setText(location.getLocationName());
CheckBox check_locations = (CheckBox) locations_row.findViewById(R.id.check_locations);
final Location location_point_a = new Location("Source");
final Location location_point_b = new Location("Destination");
location_point_a.setLatitude(Double.parseDouble(location.getLatitude()));
location_point_a.setLongitude(Double.parseDouble(location.getLongitude()));
if (position == selectedPostion) {
check_locations.setChecked(true);
} else {
check_locations.setChecked(false);
}
check_locations.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (isChecked) {
// selectedPostion = position;
latitude_string = location.getLatitude();
longitude_string = location.getLongitude();
baseLat = Double.parseDouble(latitude_string);
baseLong = Double.parseDouble(longitude_string);
for (int i = 0; i < objects.size(); i++) {
finalLat = Double.parseDouble(objects.get(i).getLatitude());
finalLong = Double.parseDouble(objects.get(i).getLongitude());
calculateDistance(baseLat, baseLong, finalLat, finalLong, "k");
}
distance_text.setText(Double.toString(calculateDistance(baseLat, baseLong, finalLat, finalLong, "k")));
} /*else {
selectedPostion = -1;
}
notifyDataSetChanged();
*/
}
});
return locations_row;
}
}
谁能告诉我如何做到这一点
【问题讨论】：
标签： android google-maps gps