BlackBerry Development Fundamentals

/*********************************************************
* Local Weather Application
 * By John M. Wargo
 * 
* This application uses the GPS capabilities of a 
* BlackBerry handheld as input to the Weather services
* provided by the US National Weather Service (NOAA)
* 
* My first thought was to just try to invoke the 
* service using the capabilities of the 4.3 hh code,
* but during researched discovered that I can just pass
* long and lat values into this URL:
* http://forecast.weather.gov/MapClick.php?textField1=41.06&textField2=-81.50
* to get the same result.
*********************************************************/
package com.bbdevfundamentals.LocalWeather;

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 net.rim.blackberry.api.browser.Browser;
import net.rim.blackberry.api.browser.BrowserSession;
import net.rim.device.api.ui.MenuItem;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.component.Menu;
import net.rim.device.api.ui.component.RichTextField;
import net.rim.device.api.ui.component.Status;
import net.rim.device.api.ui.container.MainScreen;

public class LocalWeather extends UiApplication {

 public static void main(String[] args) {
 LocalWeather theApp = new LocalWeather();
 theApp.enterEventDispatcher();
 }

 public LocalWeather() {
 pushScreen(new localWeatherScreen());
 }
}

final class localWeatherScreen extends MainScreen {

 private static String appTitle = "Local Weather";
 private RichTextField rtField;
 public LocationProvider lp;
 final String gpsError = "Unable to access GPS information.";

 public localWeatherScreen() {
 // Make sure the default menu is displayed on the scroll wheel
 super(DEFAULT_MENU | DEFAULT_CLOSE);
 // Set the title for the application
 setTitle(new LabelField(appTitle, LabelField.ELLIPSIS | LabelField.USE_ALL_WIDTH));
 // Create the rich text field, we'll populate it later
 rtField = new RichTextField("Retrieving GPS information.");
 // Add the rich text field to the screen
 add(rtField);

 // Now lets see if we have GPS capabilities
 Criteria cr = new Criteria();
 cr.setAddressInfoRequired(false);
 cr.setAltitudeRequired(false);
 cr.setPreferredResponseTime(Criteria.NO_REQUIREMENT);
 cr.setSpeedAndCourseRequired(false);
 cr.setCostAllowed(true);
 cr.setHorizontalAccuracy(Criteria.NO_REQUIREMENT);
 cr.setPreferredPowerConsumption(Criteria.NO_REQUIREMENT);
 cr.setVerticalAccuracy(Criteria.NO_REQUIREMENT);

 try {
 // set up a location provider instance
 lp = LocationProvider.getInstance(cr);
 if (lp == null) {
 // No location provider, so we can't do much.
 rtField.setText(gpsError);
 } else {                                                             
 rtField.setText("Please wait while the local weather is launched.");
 // fire off a thread to get the GPS information and launch
 // the weather URL
 Runnable initialGPSLoad = new Runnable() {
 public void run() {
 updateGPSInfo();
 }
 };
 //UiApplication.getUiApplication().invokeLater(initialGPSLoad);
 UiApplication.getUiApplication().invokeLater(initialGPSLoad);                                
 }
 } catch (LocationException le) {
 rtField.setText(gpsError);                        
 }
 }

 public void makeMenu(Menu menu, int instance) {
 // Add a simple About item to the menu
 menu.add(mnuAbout);
 };

 public MenuItem mnuAbout = new MenuItem("About", 150, 10) {
 // toss up a little screen with my name and the copyright
 public void run() {
 Status.show("By John M. Wargo\nwww.bbdevfundamentals.com.");
 }
 };

 public void updateGPSInfo() {
 Runnable gpsJob = new GPSInfo();
 Thread gpsThread = new Thread(gpsJob);
 gpsThread.start();
 }

 public class GPSInfo implements Runnable {
 public void run() {
 try {
 // Get location, one minute timeout
 // leave up to 180 seconds for autonomous mode
 Location loc = lp.getLocation(60);
 if (loc.isValid()) {
 Coordinates c = loc.getQualifiedCoordinates();
 if (c != null) {
 // use coordinate information to update the screen
 double latitude = c.getLatitude();
 double longitude = c.getLongitude();
 launchWeatherURL(latitude, longitude);
 }
 } else {
 locationError("The program returned an Invalid Location");
 }
 } catch (InterruptedException ie) {
 System.err.println(ie);
 locationError("The program raised an InterruptedException.\nException: " + ie);
 } catch (LocationException le) {
 System.err.println(le);
 locationError("The program raised a LocationException.\nException: " + le);
 } catch (Exception e) {
 System.err.println(e);
 locationError(e.getMessage());
 }
 }

 private void launchWeatherURL(final double latVal, final double longVal) {
 UiApplication.getUiApplication().invokeLater(new Runnable() {                        
 public void run() {                                     
 // http://forecast.weather.gov/MapClick.php?textField1=41.06&textField2=-81.50                                  
 String appURL = ("http://forecast.weather.gov/MapClick.php?textField1="
 + Double.toString(latVal) + "&textField2=" + Double.toString(longVal));
 // Get the default browser session
 BrowserSession browserSession = Browser.getDefaultSession();
 // Then display the page using the browser session
 browserSession.displayPage(appURL);
 // The following line is a work around to the issue found in
 // version 4.2.0
 browserSession.showBrowser();
 // Once the URL is launched, close this application
 System.exit(0);
 }
 });
 }

 private void locationError(final String errMsg) {
 UiApplication.getUiApplication().invokeLater(new Runnable() {
 public void run() {
 rtField.setText(gpsError + "\n\n" + errMsg);
 }
 });
 }
 }
}