How can I enable or disable the GPS programmatically on Android?

I know that the question about turning on/off GPS programatically on android has been discussed many times, and the answer is always the same:

"You can't for security/privacy reasons, you have to forward to location preferences screen and let the user enable/disable it."

I understand that, however I recently bought Tasker from the market and, among many other things that you can accomplish with it, you can set rules to auto-enable GPS on entering pre-determined applications and disable it on exit (see here for the tutorial on how to do it, and it just works!) and this app can't be signed with the firmware signing key as it works on many android versions and different devices and you don't even need to be rooted.

I would like to do this in my app. Of course, I don't want to blow up the users privacy, so I would first ask the user if he wants to turn it on automatically with the typical "remember my decision" checkbox and if he answers yes, enable it.

Does anybody have any idea or clue on how Tasker achieves this?

the GPS can be toggled by exploiting a bug in the power manager widget. see this xda thread for discussion.

here's some example code i use

private void turnGPSOn(){
    String provider = Settings.Secure.getString(getContentResolver(), Settings.Secure.LOCATION_PROVIDERS_ALLOWED);

    if(!provider.contains("gps")){ //if gps is disabled
        final Intent poke = new Intent();
        poke.setClassName("com.android.settings", "com.android.settings.widget.SettingsAppWidgetProvider"); 
        poke.addCategory(Intent.CATEGORY_ALTERNATIVE);
        poke.setData(Uri.parse("3")); 
        sendBroadcast(poke);
    }
}

private void turnGPSOff(){
    String provider = Settings.Secure.getString(getContentResolver(), Settings.Secure.LOCATION_PROVIDERS_ALLOWED);

    if(provider.contains("gps")){ //if gps is enabled
        final Intent poke = new Intent();
        poke.setClassName("com.android.settings", "com.android.settings.widget.SettingsAppWidgetProvider");
        poke.addCategory(Intent.CATEGORY_ALTERNATIVE);
        poke.setData(Uri.parse("3")); 
        sendBroadcast(poke);
    }
}

use the following to test if the existing version of the power control widget is one which will allow you to toggle the gps.

private boolean canToggleGPS() {
    PackageManager pacman = getPackageManager();
    PackageInfo pacInfo = null;

    try {
        pacInfo = pacman.getPackageInfo("com.android.settings", PackageManager.GET_RECEIVERS);
    } catch (NameNotFoundException e) {
        return false; //package not found
    }

    if(pacInfo != null){
        for(ActivityInfo actInfo : pacInfo.receivers){
            //test if recevier is exported. if so, we can toggle GPS.
            if(actInfo.name.equals("com.android.settings.widget.SettingsAppWidgetProvider") && actInfo.exported){
                return true;
            }
        }
    }

    return false; //default
}

All these answers are not allowed now. Here is the correct one:

For all those still looking for the Answer:

Here is how OLA Cabs and other such apps are doing it.

Add this in your onCreate

if (googleApiClient == null) {
    googleApiClient = new GoogleApiClient.Builder(this)
            .addApi(LocationServices.API).addConnectionCallbacks(this)
            .addOnConnectionFailedListener(Login.this).build();
    googleApiClient.connect();
            LocationRequest locationRequest = LocationRequest.create();
    locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    locationRequest.setInterval(30 * 1000);
    locationRequest.setFastestInterval(5 * 1000);
    LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder()
            .addLocationRequest(locationRequest);

    // **************************
    builder.setAlwaysShow(true); // this is the key ingredient
    // **************************

    PendingResult<LocationSettingsResult> result = LocationServices.SettingsApi
            .checkLocationSettings(googleApiClient, builder.build());
    result.setResultCallback(new ResultCallback<LocationSettingsResult>() {
        @Override
        public void onResult(LocationSettingsResult result) {
            final Status status = result.getStatus();
            final LocationSettingsStates state = result
                    .getLocationSettingsStates();
            switch (status.getStatusCode()) {
            case LocationSettingsStatusCodes.SUCCESS:
                // All location settings are satisfied. The client can
                // initialize location
                // requests here.
                break;
            case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
                // Location settings are not satisfied. But could be
                // fixed by showing the user
                // a dialog.
                try {
                    // Show the dialog by calling
                    // startResolutionForResult(),
                    // and check the result in onActivityResult().
                    status.startResolutionForResult(Login.this, 1000);
                } catch (IntentSender.SendIntentException e) {
                    // Ignore the error.
                }
                break;
            case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
                // Location settings are not satisfied. However, we have
                // no way to fix the
                // settings so we won't show the dialog.
                break;
            }
        }
    });
}

These are the implmented methods:

@Override
public void onConnected(Bundle arg0) {
    // TODO Auto-generated method stub

}

@Override
public void onConnectionSuspended(int arg0) {
    // TODO Auto-generated method stub

}

@Override
public void onConnectionFailed(ConnectionResult arg0) {
    // TODO Auto-generated method stub

}

Here is the Android Documentation for the same.

This is to help other guys if they are still struggling:

Edit: Adding Irfan Raza's comment for more help.

@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {
     if (requestCode == 1000) {
         if(resultCode == Activity.RESULT_OK){
             String result=data.getStringExtra("result"); 
         } if (resultCode == Activity.RESULT_CANCELED) {
             //Write your code if there's no result 
         } 
    } 
} 

ENABLE GPS:

Intent intent=new Intent("android.location.GPS_ENABLED_CHANGE");
intent.putExtra("enabled", true);
sendBroadcast(intent);

DISABLE GPS:

Intent intent = new Intent("android.location.GPS_ENABLED_CHANGE");
intent.putExtra("enabled", false);
sendBroadcast(intent);