在调试我的android-java代码时需要帮助

Question

Log cat shows "Runtime exception - cant create handler inside thread that has not called looper.prepare??I want to send location update of my phone to some other phone via sms after a fixed interval of time.Please help . Suggest ways to save power also

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
 et1 = (EditText)findViewById(R.id.editText1);
 et2 = (EditText)findViewById(R.id.editText2);
 b1  = (Button)findViewById(R.id.button1 );
 t1 = new Timer();
 t2 = new Timer();
 lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
 listener = new LocationListener() {

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderDisabled(String provider) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onLocationChanged(Location location) {
        // TODO Auto-generated method stub
        SmsManager sm = SmsManager.getDefault();
         String message = String.format(
                    "New Location \n Longitude: %1$s \n Latitude: %2$s",
                    location.getLongitude(), location.getLatitude()             );
        String number = "5556";
        sm.sendTextMessage(number,null,message,null,null);
    }
};

Schedule request update after every fixed interval

t1.scheduleAtFixedRate(new TimerTask() {

    @Override
    public void run() {
        // TODO Auto-generated method stub
        lm.requestSingleUpdate(LocationManager.GPS_PROVIDER, listener,null);
    }
},0,300000);

}

}

Answer 1

It's not clear from the TimerTask documentation, but I suspect each task runs on its own thread. Also, the documentation for the LocationManager.requestSingleUpdate call you're using says “If looper is null then the callbacks will be called on the main thread”, but I suspect this is wrong, because it disagrees with the one with the alternative signature, which says “If looper is null then the callbacks will be called on the current thread”. If the latter is correct, that would explain your problem, because you are calling requestSingleUpdate within your TimerTask thread, which has no Looper .

Perhaps use the result from getMainLooper instead of null for the last arg to requestSingleUpdate .

Answer 2

That error basically means "You are trying to do something in a background thread that you are not allowed to do in a background thread.

Your listener will handle the asynchronous nature of the location request. You do not need to thread it.

If you DO need things threaded, read up on Asynctask .