Finding position in Java ME

Comments

24 Sep
2009

Article Review by kalki (20090924)

Article is all about using how to make Location Based Application. LBS application use some basic information to find some interesting places.Articles gives code example of usage of Location Class and its different methods. Ways to get Current Position of the Device or user.

Code Given in this article can become the primary source for those who wants to develop LBS application. Code Example should must try. It gives expected out.

Ravindrashenoy - Not working for E63

Hello, i built this application and tried to run it on nokia e63. Its not working on that. It gives a Location request timeout exception. I understand that e63 doesnt have builtin GPS, but the API should be able to get network based location right?

Any pointers?

ravindrashenoy 16:11, 8 May 2012 (EEST)

Skalogir - Network based location retrieval is only supported on Series 40 devices

Please check my answer on this thread:

http://www.developer.nokia.com/Community/Discussion/showthread.php?235485-java-Location-api-not-working&p=893457#post893457

skalogir 22:29, 11 May 2012 (EEST)

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This code snippet demonstrates how to retrieve device coordinates in Java ME. It uses LocationProvider.getInstance() to obtain LocationProvider instance, which represents a location-providing module, generating Locations, and LocationProvider.getLocation() method to retrieve current latitude and longitude.

Article Metadata

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Code Example

Source file: Media:Finding position in Java ME.zip

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Tested with

Devices(s): Nokia 2710N

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Compatibility

Platform(s): Since S60 3rd Edition, Since Series 40 6th Edition

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Article

Keywords: javax.microedition.location.LocationProvider,javax.microedition.location.Location,javax.microedition.location.Coordinates.getLatitude,javax.microedition.location.Coordinates.getLongitude()

Created: vltsoy (08 Dec 2008)

Reviewed: skalogir (06 Oct 2011)

Last edited: hamishwillee (21 May 2013)

Source file: FindingPosition.java

import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.StringItem;
import javax.microedition.location.Coordinates;
import javax.microedition.location.Criteria;
import javax.microedition.location.Location;
import javax.microedition.location.LocationException;
import javax.microedition.location.LocationProvider;
import javax.microedition.midlet.MIDlet;
 
public class FindingPosition extends MIDlet implements CommandListener {
 
    private Display display;
    private Form form;
    private Command exitCommand;
    private Command refreshCommand;
    private StringItem text;
 
    private Location location;
    private LocationProvider locationProvider;
    private Coordinates coordinates;
    private Criteria criteria;
 
    /**
     * Constructor. Constructs the object and initializes displayables.
     */
    public FindingPosition() {
        form = new Form("Finding location.");
 
        exitCommand = new Command("Exit", Command.EXIT, 2);
        refreshCommand = new Command("Refresh", Command.OK, 1);
 
        text = new StringItem("Your position:", "\nPress \"Refresh\"");
        form.append(text);
 
        form.addCommand(exitCommand);
        form.addCommand(refreshCommand);
        form.setCommandListener(this);
 
        display = Display.getDisplay(this);
        display.setCurrent(form);
 
        criteria = new Criteria();
        criteria.setHorizontalAccuracy(500);
 
        try {
            locationProvider = LocationProvider.getInstance(criteria);
        } catch (LocationException e) {
            //TODO: Handle location exception.
            return;
        }
    }
 
    /**
     * From MIDlet.
     * Called when the MIDlet is started.
     */
    public void startApp() {
        // No implementation required.
    }
 
    /**
     * From MIDlet.
     * Called to signal the MIDlet to enter the Paused state.
     */
    public void pauseApp() {
        // No implementation required.
    }
 
    /**
     * From MIDlet.
     * Called to signal the MIDlet to terminate.
     * @param unconditional whether the MIDlet has to be unconditionally
     * terminated
     */
    public void destroyApp(boolean unconditional) {
        // No implementation required
    }
 
    /**
     * From CommandListener.
     * Called by the system to indicate that a command has been invoked on a
     * particular displayable.
     * @param cmd the command that was invoked
     * @param displayable the displayable where the command was invoked
     */
    public void commandAction(Command c, Displayable d) {
        if (c == refreshCommand) {
            checkLocation();
        } else if (c == exitCommand) {
            notifyDestroyed();
        }
    }
 
    /**
     * Called to read current location.
     */
    private void checkLocation() {
        String string;
 
        try {
            location = locationProvider.getLocation(60);
        } catch (Exception e) {
            //TODO: Handle exception.
            return;
        }
 
        coordinates = location.getQualifiedCoordinates();
        if (coordinates != null) {
            // Use coordinate information 
            double lat = coordinates.getLatitude();
            double lon = coordinates.getLongitude();
            string = "\nLatitude : " + lat + "\nLongitude : " + lon;
        } else {
            string = "Location API failed";
        }
        text.setText(string);
    }
}

Postconditions

After user press "refresh", MIDlet will show current coordinates.

Supplementary material

You can see source file and executable application in attached zip archive. Archive is available for download at Finding_position_in_Java_ME.zip