SmsService...

SmsService.java

package ee.era.geek.sms_spammer.service;

import android.app.Service;
import android.content.Intent;
import android.os.*;
import android.telephony.SmsManager;
import android.text.format.DateFormat;
import android.util.Log;
import ee.era.geek.sms_spammer.ConfigUtil;

import java.util.Date;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;

import static java.util.concurrent.TimeUnit.*;


public class SmsService extends Service {
    private Messenger messenger;
    private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
    public static final String MESSENGER = "MESSENGER";

    @Override
    public int onStartCommand(final Intent intent, final int flags, final int startId) {
        if (messenger == null){ readIntent(intent);}

        Log.i(getClass().toString(), "Read message data");
        final ConfigUtil conf = ConfigUtil.getInstance(getApplicationContext());
        final String number = conf.getNumber();
        final String msg = conf.getMsg();

        final Integer min = Integer.parseInt(conf.getMin());
        final Integer max = Integer.parseInt(conf.getMax());

        final Runnable smsTask = new Runnable() {
            public void run() {
                int val = getRandomInterval(min, max);
                Log.i(getClass().toString(), "Sending message to " + number +
                        " next interval in " + val + " SECONDS");

                sendSms(number, msg);
                sendMessageToUi("Sending message to " + number +
                        " next interval in " + val + " SECONDS");

                scheduler.schedule(this, val, SECONDS);
            }

        };

        scheduler.schedule(smsTask, getRandomInterval(min, max), SECONDS);
        return super.onStartCommand(intent, flags, startId);
    }

    public static int getRandomInterval(int min, int max){
        return min + (int)(Math.random() * ((max - min)+1));
    }

    private void readIntent(Intent intent) {
        Log.i(getClass().toString(), "Reading intent..");
        Bundle extras = intent.getExtras();
        if (extras != null) { messenger = (Messenger) extras.get(MESSENGER);}
    }

    private void sendSms(String number, String message){
        SmsManager sm = SmsManager.getDefault();
        sm.sendTextMessage(number, null, message, null, null);
    }

    private void sendMessageToUi(String message) {
        try {
            messenger.send(makeMessage(message));
        } catch (RemoteException e) {
            Log.w(getClass().getName(), "Exception sending message to UI", e);
        }
    }

    private Message makeMessage(String message) {
        Message msg = Message.obtain();
        msg.obj = DateFormat.format("yyyy-MM-dd hh:mm:ss ", new Date().getTime()).toString() + message;
        return msg;
    }

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

    @Override
    public void onDestroy() {
        Log.i(getClass().getName(), "onDestroy fired...");
        scheduler.shutdownNow();
        super.onDestroy();
    }
}