My app works on one phone but not another

[Marshal Gaddis]

Hey guys,

I have a very simple app that basically just runs a single equation and spits out the answer. Unfortunately, while writing it, I was using a buddy's Galaxy S and now when I try to run it on my HTC Hero for Sprint (or an AVD), I'm getting errors.

The Code:

package com.marshal.stella;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.TimeZone;

import android.app.Activity;
import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.TextView;

public class HelloActivity extends Activity {
	
	private static final double REFERENCE_LONGITUDE = -103.616111;
	private static final int REFERENCE_ZERO_DAY = 140;
	private static final TimeZone REFERENCE_TIMEZONE =
		TimeZone.getTimeZone("America/Chicago");

	
   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       
       Location loc;
       loc = getLocation();
       
       int day = computeBigFormula();
       Calendar cal = Calendar.getInstance();
       cal.set(Calendar.DAY_OF_YEAR, day);
       
       String blah;
       blah = "Latitude: " + loc.getLatitude() + "; Longitude: " + loc.getLongitude()
       	+ "; Accuracy in Meters: " + loc.getAccuracy()
       	+ "\n Time Zone Difference: " + timeZoneDiff() +
       	 "\n Day of the Year: " + day +
       	 "\n Pablo Date: " + (new SimpleDateFormat("MMMMM d")).format(cal.getTime());
       
       
       TextView tv = new TextView(this);
       tv.setText(blah);
       setContentView(tv);
   }
   
   private Location getLocation() {
	   LocationManager locationService =
		   (LocationManager)
		   this.getSystemService(Context.LOCATION_SERVICE);
	   Criteria crit = new Criteria();
	   //crit.setAccuracy(Criteria.ACCURACY_FINE);
	   crit.setAccuracy(Criteria.NO_REQUIREMENT);
	   String provider = locationService.getBestProvider(crit, true);
	   //List <String> providers = locationService.getProviders(true);
	   //String provider = providers.get(0);
	   Location mostRecentLocation = locationService.getLastKnownLocation(provider);
	   
	   return mostRecentLocation;
   }
   
   // In hours
   public long timeZoneDiff() {
	   long currOffset = Calendar.getInstance().getTimeZone().getRawOffset();
	   long terlOffset = REFERENCE_TIMEZONE.getRawOffset();
	   return (terlOffset - currOffset) / (1000 * 3600);
   }
   
   private int computeBigFormula() {
	   Location l = getLocation();
	   // XXX check for null
	   double lon = l.getLongitude();
	   return (int) ((REFERENCE_LONGITUDE - lon) + 15 * timeZoneDiff() +
			   REFERENCE_ZERO_DAY);
   }
}

The Error:

12-21 15:46:26.233: DEBUG/dalvikvm(14147): GC freed 1084 objects / 73992 bytes in 143ms
12-21 15:46:54.513: DEBUG/Sync(87): Received network tickle for [e-mail] - https://mail.google.com/mail/g/?client=1291616835746
12-21 15:47:35.613: DEBUG/Sync(87): Received network tickle for [e-mail] - https://mail.google.com/mail/g/?client=1291616835746
12-21 15:47:44.123: WARN/dalvikvm(87): disableGcForExternalAlloc: true
12-21 15:47:44.123: INFO/ActivityManager(87): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.marshal.stella/.HelloActivity }
12-21 15:47:44.203: INFO/ActivityManager(87): Start proc com.marshal.stella for activity com.marshal.stella/.HelloActivity: pid=23911 uid=10082 gids={1015}
12-21 15:47:44.373: DEBUG/dalvikvm(55): GC freed 290 objects / 11064 bytes in 162ms
12-21 15:47:44.403: INFO/dalvikvm(23911): Debugger thread not active, ignoring DDM send (t=0x41504e4d l=38)
12-21 15:47:44.433: DEBUG/AK8973(61): Compass Start
12-21 15:47:44.443: DEBUG/Sensors(87): open_akm, fd=135
12-21 15:47:44.543: INFO/dalvikvm(23911): Debugger thread not active, ignoring DDM send (t=0x41504e4d l=40)
12-21 15:47:44.613: DEBUG/dalvikvm(55): GC freed 57 objects / 2480 bytes in 220ms
12-21 15:47:44.663: DEBUG/LocationManager(23911): Constructor: service = android.location.ILocationManager$Stub$Proxy@44429c20
12-21 15:47:44.683: DEBUG/AndroidRuntime(23911): Shutting down VM
12-21 15:47:44.693: WARN/dalvikvm(23911): threadid=3: thread exiting with uncaught exception (group=0x4001e390)
12-21 15:47:44.693: ERROR/AndroidRuntime(23911): Uncaught handler: thread main exiting due to uncaught exception
12-21 15:47:44.733: ERROR/AndroidRuntime(23911): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.marshal.stella/com.marshal.stella.HelloActivity}: java.lang.IllegalArgumentException: provider==null
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2596)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2621)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at android.app.ActivityThread.access$2200(ActivityThread.java:126)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1932)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at android.os.Handler.dispatchMessage(Handler.java:99)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at android.os.Looper.loop(Looper.java:123)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at android.app.ActivityThread.main(ActivityThread.java:4595)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at java.lang.reflect.Method.invokeNative(Native Method)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at java.lang.reflect.Method.invoke(Method.java:521)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at dalvik.system.NativeStart.main(Native Method)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911): Caused by: java.lang.IllegalArgumentException: provider==null
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at android.location.LocationManager.getLastKnownLocation(LocationManager.java:941)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at com.marshal.stella.HelloActivity.getLocation(HelloActivity.java:58)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at com.marshal.stella.HelloActivity.onCreate(HelloActivity.java:29)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2544)
12-21 15:47:44.733: ERROR/AndroidRuntime(23911):     ... 11 more

Any Ideas? Thanks a lot!

[Misha van Tol]

Please UseCodeTags.
It makes it easier to link the errors to the specific line of code that caused it. As far as I can see now the problem is your provider string is null, so when you try to use it later on in the code it gives you an NullPointerException. Try editing the first post adding code tags and post also 15 lines of logcat just before the error part, many times there you'll find a detailed answer to what went wrong.

BTW, what is the purpose of the code?

[Marshal Gaddis]

Ah ha! So that's you add that nice code formatting. Please see the above post for the changes you suggested. And thank you for slogging through it when it was in plain text.

As far as the purpose-- it's meant to give a date that can be used to tell the time by the stars from wherever the phone happens to be. It subtracts the difference in time zones between that of my home town and that of wherever the phone is from the difference in longitudes and adds a special date that we use in my home town. ie:

[Longitude of phone - longitude of hometown] + 15 [time zone hometown - timezone phone] + special date in home town.

If you're genuinely interested, check out this website:

http://www.johnpratt.com/items/astronomy/telltime.html

--What this website doesn't mention is that the special date (on the website, it says March 7) varies by about 15-20 days in the US and can vary up to 50 days in other parts of the world depending on your longitude... all because of man's timezones.

Thanks again for your help.

[Misha van Tol]

As far as I can see it looks like you haven't set permissions to use the GPS in your manifest.

<?xml version="1.0" encoding="UTF-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
...
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission>
</manifest>

[Ulf Dittmer]

As far as I can see it looks like you haven't set permissions to use the GPS in your manifest.

While that's a possibility, I think it's unlikely to be the cause of the problem if the application worked fine on some other device.

Make sure that either GPS or network location is enabled on your device under "Settings -> Location and Security".

[Misha van Tol]

While that's a possibility, I think it's unlikely to be the cause of the problem if the application worked fine on some other device.
Make sure that either GPS or network location is enabled on your device under "Settings -> Location and Security".

Ulf is right here. (I was checking with enabledOnly set to false)
So, just check for null-results while getting the location and keep in mind that there's always a possibility that it's impossible to get a location and make sure your app can handle those situations gracefully.

[Marshal Gaddis]

Thanks a lot, guys. I was so confident there was error in my code that I didn't make sure my location settings were set correctly.

The issue was, in fact, with my phone.