Create an Android location from a string array

Question

I'm developing an Android app. I need to compare locations and see what the distance is between them. However, I have a lot of them. The easiest way I have found is to store them in a string-array, and then to compare them. I have searched, but I have not found a way to make an item from a string array into a location. I tried:

double distance

Location locationA = new Location(“point A”)

locationA.setLatitude(latitude);

locationA.setLongitude(Longitude);

Location locationB = new Location(“point B”);

locationB.setLatitude(Latitude.get(0));

LocationB.setLongitude(latitude.get(0));

distance = locationA.distanceTo(locationB);

But it does not work. My code is posted below:

NearestStations.java

public class Neareststations extends Activity implements LocationListener {
LocationManager mLocationManager;
@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.neareststations);
    // Show the Up button in the action bar.
    getActionBar().setDisplayHomeAsUpEnabled(true);



        mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

        Location location = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
        double longitude = location.getLongitude();
        double latitude = location.getLatitude();
        Log.i("MYTAG", String.valueOf(longitude));
        Log.i("MYTAG", String.valueOf(latitude));
        if(location != null && location.getTime() > Calendar.getInstance().getTimeInMillis() - 2 * 60 * 1000) {
            // Do something with the recent location if it is less than two minutes old
            Log.i("MYTAG", String.valueOf(location));
            Log.i("MYTAG", String.valueOf(longitude));
            Log.i("MYTAG", String.valueOf(latitude));
        }
        else {
            mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 5, 50, this);
            Log.i("MYTAG", String.valueOf(location));
        }
    }

    public void onLocationChanged(Location location) {
        if (location != null) {
        // Do something withthe current location
            Log.i("MYTAG", String.valueOf(location));

        }
    }

    public void onProviderDisabled(String arg0) {}
    public void onProviderEnabled(String arg0) {}
    public void onStatusChanged(String arg0, int arg1, Bundle arg2) {}

    String[] Stations = getResources().getStringArray(R.array.Stations);
    String[] Longitude = getResources().getStringArray(R.array.Longitude);
    String[] Latitude = getResources().getStringArray(R.array.Latitude);

    Map<String, String> myMap = new HashMap<String, String>();{
    for (int i = 0; i <8; i++) {
        myMap.put(Stations[i], Latitude[i]);
    }
    }

    Map<String, String> myMap1 = new HashMap<String, String>();{
    for (int h = 0; h <8; h++) {
        myMap1.put(Stations[h], Longitude[h]);
    }
    }

How can I do this? My string-array's are standard and have entries such as

<item>-87.669147</item>
<item>-87.680622</item>

Thank you for your help.

But it does not work. means that you're getting zero or crashes or ... what? Also, I believe you have some typo as you're having LocationB.setLongitude(latitude.get(0));. At least from method naming shouldn't you provide a longitude? — gunar
– gunar, Commented Oct 9, 2013 at 21:45
What do you mean by doesn't work? Do you get the wrong location? Do you get an exception or a crash? Please post actual information so we can help oyu. — Kasra Rahjerdi
– Kasra Rahjerdi, Commented Oct 9, 2013 at 21:45

Island Wave · Accepted Answer · 2013-10-10 02:57:47Z

5

The strings need to be converted into doubles. Also, you should be using distanceBetween() when comparing two points but distanceTo() will work fine for smaller distances.

Here's a basic example of converting String values to doubles for use with Location. Distance will be returned in meters, so multiply by 0.000621371192237334 if you want miles.

double distance;  

String str_lat_start = "29.287260";
String str_lon_start = "-81.100327";
String str_lat_end = "26.016045";
String str_lon_end = "-80.150169";

double lat_start = 0;
double lon_start = 0;
double lat_end = 0;
double lon_end = 0;

try {

    lat_start = Double.parseDouble( str_lat_start ); 
    lon_start = Double.parseDouble( str_lon_start );
    lat_end = Double.parseDouble( str_lat_end );
    lon_end = Double.parseDouble( str_lon_end );

} catch (NumberFormatException e) {
    Log.v("Main", "Convert to Double Failed : ");
}

Location locationA = new Location("point A");  
locationA.setLatitude( lat_start );  
locationA.setLongitude( lon_start );  

Location locationB = new Location("point B");  
locationB.setLatitude( lat_end );  
locationB.setLongitude( lon_end );  

distance = locationA.distanceTo(locationB) * 0.000621371192237334;

edited Oct 10, 2013 at 2:57

answered Oct 9, 2013 at 21:49

Island Wave

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5 Comments

hichris123 Over a year ago

Correct me if I'm wrong, but isn't distanceBetween() only used for long distances?

hichris123 Over a year ago

Also, can you post some code for the converting part? I get The method convert(String) is undefined for the type Double when I try Double G; G.convert(Lon);

Island Wave Over a year ago

Updated with a code example for converting string to double. You'll want to perform conversion in a try block and catch exceptions, otherwise your app will crash.

Island Wave Over a year ago

Also, if you're using LocationManager, you'll want to add these permissions to your Manifest..... <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

hichris123 Over a year ago

Thanks, that looks great. Is there an easy way to iterate this or repeat it, because I have a lot of these I need to do.

S.Thiongane · Accepted Answer · 2013-10-09 22:00:32Z

1

float[] results = new float[3];
    Location.distanceBetween(locationA.getLatitude(), locationA.getLongitude(), locationB.getLatitude(), locationB.getLongitude(), results);

Distance between A and B is results[0].

answered Oct 9, 2013 at 22:00

S.Thiongane

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