Instant signal strength

Question

I need to find a way to measure the current signal strength of Android phone, without the need to register a PhoneStateListener that God knows when it returns the actual asu

Answer 1

class Signal {

    static volatile CountDownLatch latch;
    static int asu;
    private final static String TAG = Signal.class.getName();

    int getSignalStrength(Context ctx) throws InterruptedException {
        Intent i = new Intent(TAG + ".SIGNAL_ACTION", Uri.EMPTY, ctx,
                SignalListenerService.class);
        latch = new CountDownLatch(1);
        asu = -1;
        ctx.startService(i);
        Log.w(TAG, "I wait");
        latch.await();
        ctx.stopService(i);
        return asu;
    }
}

where :

public class SignalListenerService extends Service {

    private TelephonyManager Tel;
    private SignalListener listener;
    private final static String TAG = SignalListenerService.class.getName();

    private static class SignalListener extends PhoneStateListener {

        private volatile CountDownLatch latch;

        private SignalListener(CountDownLatch la) {
            Log.w(this.getClass().getCanonicalName(), "CSTOR");
            this.latch = la;
        }

        @Override
        public void onSignalStrengthChanged(int asu) {
            Signal.asu = asu;
            latch.countDown();
        }
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.w(TAG, "Received : " + intent.getAction());
        Tel = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
        listener = new SignalListener(Signal.latch);
        @SuppressWarnings("deprecation")
        final int listenSs = PhoneStateListener.LISTEN_SIGNAL_STRENGTH;
        Tel.listen(listener, listenSs);
        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        Log.w(TAG, "onDestroy");
        Tel.listen(listener, PhoneStateListener.LISTEN_NONE);
        super.onDestroy();
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

This is working code. Do not forget to register your services in the manifest and acquire permissions. There may be better/ more elegant ways of doing this so comments/corrections welcome.