I want to implement a simple messenger application for Android devices,I'm working with a web service which contains all the required methods for sending and receiving(by pressing the send button a record will be inserted in the DB and by calling the receive method all the rows related to this receiver(user) are retrieved).
I've written a service in a separate class and in onStart() I check the receive method of my .Net web service,I start the service in onCreate() of my activity ,so the service is in the background and receives the incoming messages perfectly,I can show the new message by using a toast directly in my service code,but I know that for accessing the views which are in my activity I should use pendingintent and maybe a BroadcastReceiver,so I can add the new messages to the main screen of my activity(for example a textview).
Now I want to find a way to access the textview of my activity and set the text of it through my service or anything else...
please help me on this issue,
Here is my activity:
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MyOwnActivity extends Activity
{
Button btnSend;
Button btnExtra;
EditText txtMessageBody;
TextView lblMessages;
BerryService BS = new BerryService();
public void SetMessageHistory(String value)
{
txtMessageBody.setText(value);
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnSend = (Button) findViewById(R.id.btnSend);
btnExtra = (Button) findViewById(R.id.btnExtraIntent);
txtMessageBody = (EditText) findViewById(R.id.txtMessageBody);
lblMessages = (TextView) findViewById(R.id.lblMessages);
/////////
//////////
startService(new Intent(this, IncomingMessageService.class));
btnSend.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// call webservice method to send
BS.SetSoapAction("http://tempuri.org/Send");
BS.SetMethodName("Send");
String a = BS.SendMessage(txtMessageBody.getText().toString());
lblMessages.setText(lblMessages.getText().toString() + "\n"
+ txtMessageBody.getText().toString());
txtMessageBody.setText("");
}
});
}
}
Here is my service:
import java.util.Timer;
import java.util.TimerTask;
import android.app.ActivityManager;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.os.Handler;
import android.os.IBinder;
import android.os.SystemClock;
import android.widget.Toast;
public class IncomingMessageService extends Service
{
private static final int NOTIFY_ME_ID = 12;
BerryService BS = new BerryService();
String text = "";
#Override
public IBinder onBind(Intent intent) {
throw new UnsupportedOperationException("Bind Failed");
}
#Override
public void onCreate() {
Toast.makeText(this, "onCreate", 5000).show();
}
#Override
public void onStart(Intent intent, int startId) {
// ////////////////////////
Toast.makeText(this, "onStart ", 1000).show();
// Timer Tick
final Handler handler = new Handler();
Timer _t = new Timer();
TimerTask tt = new TimerTask() {
#Override
public void run() {
handler.post(new Runnable() {
public void run() {
Toast.makeText(getApplicationContext(), "tick ", 1000)
.show();
// here the receive method should be called
BS.SetSoapAction("http://tempuri.org/RecieveMessage");
BS.SetMethodName("RecieveMessage");
String receivedMsg = BS.ReceiveMessage("sh");
//Instead of toast I want to access the textview in my activity!!!!!
Toast.makeText(getApplicationContext(), receivedMsg, 5000).show();
}
});
}
};
_t.scheduleAtFixedRate(tt, 0, 1000);
}
// /
#Override
public void onDestroy() {
Toast.makeText(this, "onDestroy", 5000).show();
}
}
You need to understand the concept of Broadcast, in your case it is the correct solution.
Start Broadcast in its activity
public static final String ACTION = "com.yourapp.ACTION.TEXT_RECEIVED";
private BroadcastReceiver mReceiver;
#Override
public void onCreate(Bundle savedInstanceState) {
////////
mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String msg = intent.getStringExtra("msg");
yourTextView.setText(msg);
}
};
IntentFilter filter = new IntentFilter(ACTION);
filter.addCategory(Intent.CATEGORY_DEFAULT);
registerReceiver(mReceiver, filter);
////////
}
protected void onDestroy() {
// remember to unregister the receiver
super.onDestroy();
if (mReceiver != null) {
unregisterReceiver(mReceiver);
}
}
When you need to send the message of service you should use:
Intent i = new Intent();
i.setAction(MyOwnActivity.ACTION);
i.addCategory(Intent.CATEGORY_DEFAULT);
i.putExtra("msg", "the message received by webservice");
i.putExtras(b);
sendBroadcast(i);
Have a look here: http://developer.android.com/reference/android/content/BroadcastReceiver.html
Using a broadcast manager is great but I personally prefer to use square's Otto because it is just so easy to perform communication between components in an android application.
http://square.github.io/otto/
If you do choose to use otto, you are going to have to override the Bus's post method to be able to talk post messages to a bus on the foreground. Here is the code for that:
public class MainThreadBus extends Bus {
private final Handler handler = new Handler(Looper.getMainLooper());
#Override public void post(final Object event) {
if (Looper.myLooper() == Looper.getMainLooper()) {
super.post(event);
} else {
handler.post(new Runnable() {
#Override
public void run() {
post(event);
}
});
}
}
}
Related
I like to exit my application immediately after starting a service.
The code below causes the activity to finish before the service is started.
How do I set a listener to prompt me when the service is started?
btn = (ImageButton) findViewById(R.id.button );
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startService(new Intent(MainActivity.this, MyService.class));
//I want to exit the activity here.
finish(); // this exits the activity before the service is started
}
});
The following are the codes I used, based on the proposal by #Er.Arjunsaini
on the ACTIVITY file, I register to listen for an "Exit App" broadcast.
private final BroadcastReceiver exitAppReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
//activity exits when "exit app" broadcast received.
finish();
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//REGISTER TO LISTEN FOR THE BROADCAST
LocalBroadcastManager.getInstance(this).
registerReceiver(exitAppReceiver, new IntentFilter(getString(R.string.exit_app)));
btn = (ImageButton) findViewById(R.id.my_button);
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startService( new Intent(this, MyService.class));
}
});
}
#Override
public void onDestroy() {
//UNREGISTER THE RECEIVER
LocalBroadcastManager.getInstance(this).
unregisterReceiver(exitFloatingWindowReceiver);
super.onDestroy();
}
on the SERVICE file, I send an "Exit APP" broadcast.
#Override
public void onCreate() {
super.onCreate();
//... do the rest of the Service initializing
//CLOSE ACTIVITY
LocalBroadcastManager.getInstance(this).
sendBroadcast(new Intent(getString(R.string.exit_app)));
}
check out ServiceConnection, onServiceConnected may be method you are looking for to call finish()
HERE you have example
If you use bindService() instead of startService(), you can use the Message based communication system between Activity and Service.
This is explained in this reference.
At the end of the section there's a link to sample classes:
-MessengerService.java
-MessengerServiceActivities.java
Here an example of an Activity with 2 button, one for starting the Service and one for sending a message to the Service that will resend a message to the Activity to close it.
MainActivity.java
package com.pasquapp.brodcasttest01;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.Messenger;
import android.os.RemoteException;
import android.view.View;
import android.widget.Button;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
public final static int WHAT_CLOSE_ACTIVITY=1;
private Button startServiceButton;
private Button closeButton;
private Messenger activityMessenger;
private Messenger serviceMessenger;
private MyServiceConnection serviceConnection;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
activityMessenger =new Messenger(new ActivityHandler());
initView();
}
#Override
protected void onDestroy() {
super.onDestroy();
if(serviceConnection!=null)
unbindService(serviceConnection);
}
private void initView(){
startServiceButton=findViewById(R.id.button_start_service);
startServiceButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startService();
}
});
closeButton=findViewById(R.id.button_close);
closeButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if(serviceMessenger!=null){
Message msg=Message.obtain();
msg.replyTo=activityMessenger;
msg.what=MyService.WHAT_CLOSE_ACTIVITY;
try {
serviceMessenger.send(msg);
} catch (RemoteException e) {
e.printStackTrace();
}
}
}
});
}
private class MyServiceConnection implements ServiceConnection{
#Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
serviceMessenger=new Messenger(iBinder);
}
#Override
public void onServiceDisconnected(ComponentName componentName) {
serviceMessenger=null;
}
}
private void startService(){
serviceConnection=new MyServiceConnection();
bindService(new Intent(this,MyService.class),serviceConnection,BIND_AUTO_CREATE);
}
private class ActivityHandler extends Handler{
#Override
public void handleMessage(#NonNull Message msg) {
int what=msg.what;
switch (what){
case WHAT_CLOSE_ACTIVITY:
MainActivity.this.finish();
break;
default:
super.handleMessage(msg);
}
}
}}
MyService.java
package com.pasquapp.brodcasttest01;
import android.app.Service;
import android.content.Intent;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.Messenger;
import android.os.RemoteException;
import androidx.annotation.NonNull;
public class MyService extends Service {
public static final int WHAT_CLOSE_ACTIVITY=1;
private Messenger mMessenger;
public MyService() {
}
#Override
public void onCreate() {
super.onCreate();
mMessenger=new Messenger(new ServiceHandler());
}
#Override
public IBinder onBind(Intent intent) {
return mMessenger.getBinder();
}
private class ServiceHandler extends Handler{
#Override
public void handleMessage(#NonNull Message msg) {
int what=msg.what;
switch (what){
case WHAT_CLOSE_ACTIVITY:
Messenger messenger=msg.replyTo;
Message closeMsg=Message.obtain();
closeMsg.what=MainActivity.WHAT_CLOSE_ACTIVITY;
try {
messenger.send(closeMsg);
} catch (RemoteException e) {
e.printStackTrace();
}
break;
default:
super.handleMessage(msg);
}
}
}
}
I'm supposed to add a timer to my service class that prints a message to LogCat every 10 seconds. Nothing in the service class is printing once I call the startService method and I have no idea why.. Any ideas?
package com.murach.reminder;
import android.content.Intent;
import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
public class ReminderActivity extends Activity implements OnClickListener {
private Button startServiceButton;
private Button stopServiceButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_reminder);
startServiceButton = (Button) findViewById(R.id.startServiceButton);
stopServiceButton = (Button) findViewById(R.id.stopServiceButton);
startServiceButton.setOnClickListener(this);
stopServiceButton.setOnClickListener(this);
}
#Override
public void onClick(View v) {
Intent serviceIntent = new Intent(this, ReminderService.class);
switch (v.getId()) {
case R.id.startServiceButton:
// put code to start service and display toast here
startService(serviceIntent);
Toast.makeText(this, "Service started", Toast.LENGTH_SHORT).show();
break;
case R.id.stopServiceButton:
// put code to stop service and display toast here
stopService(serviceIntent);
Toast.makeText(this, "Service stopped", Toast.LENGTH_SHORT).show();
break;
}
}
}
package com.murach.reminder;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;
import java.util.Timer;
import java.util.TimerTask;
public class ReminderService extends Service
{
private Timer timer;
public void onCreate()
{
Log.d("Reminder", "Service created");
startTimer();
}
#Override
public IBinder onBind(Intent intent)
{
Log.d("Reminder", "No binding for this activity");
return null;
}
public void onDestroy()
{
Log.d("Reminder", "Service destroyed");
stopTimer();
}
private void startTimer() {
TimerTask task = new TimerTask() {
public void run() {
Log.d("Reminder", "Timer task executed");
}
};
timer = new Timer(true);
int delay = 1000 * 10;
int interval = 1000 * 10;
timer.schedule(task, delay, interval);
}
private void stopTimer()
{
if (timer != null)
{
timer.cancel();
}
}
}
And here is how I register the service in the Manifest (in a service element, it wouldn't let me type it out completely)
android:name="com.murach.reminder.ReminderService"
The package names do not match. There is a spelling mistake in the word murach in your Manifest declaration.
I am trying to implement a service in Android that displays a toast message every 1 minute in Android. I am new to Android development and learned about AlarmManager that will help me do this. I have implemented the code in the following way:
This is my IIManagerActivity class
package com.example.iimanager;
import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.SystemClock;
import android.view.Menu;
import android.widget.Toast;
public class IIManagerActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_iimanager);
AlarmManager mgr=(AlarmManager)getSystemService(Context.ALARM_SERVICE);
Intent i=new Intent(this, SampleService.class);
PendingIntent pi=PendingIntent.getService(this, 0, i, 0);
mgr.setInexactRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, SystemClock.elapsedRealtime(), AlarmManager.INTERVAL_FIFTEEN_MINUTES/900, pi);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_iimanager, menu);
return true;
}
}
And this is my SampleService that is meant to display a toast message.
For some reason I cannot get to see a toast message no matter how long I wait.
package com.example.iimanager;
import android.app.IntentService;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
public class SampleService extends IntentService {
public SampleService() {
super("SimpleService");
//Toast.makeText(getApplicationContext(), "this is my Toast message!!! =)", Toast.LENGTH_LONG).show();
}
#Override
protected void onHandleIntent(Intent intent) {
//do something
Toast.makeText(getApplicationContext(), "this is my Toast message!!! =)", Toast.LENGTH_LONG).show();
}
}
Can you please tell me what's wrong and what needs to be done to get it corrected?
Thank you very much in advance.
Copy the below 3 lines for toast call
Timer timer = new Timer();
TimerTask updateProfile = new SampleService(SampleService.this);
timer.scheduleAtFixedRate(updateProfile, 10,1000);
class CustomTimerTask extends TimerTask {
private Context context;
private Handler mHandler = new Handler();
// Write Custom Constructor to pass Context
public CustomTimerTask(Context con) {
this.context = con;
}
#Override
public void run() {
new Thread(new Runnable() {
#Override
public void run() {
mHandler.post(new Runnable() {
#Override
public void run() {
Toast.makeText(getApplicationContext(), "this is my Toast message!!! =)", Toast.LENGTH_LONG).show();
}
});
}
}).start();
}
}
Try following code,
MainActivity.java
public class MyService extends Service {
public static final long INTERVAL=60000;//variable for execute services every 1 minute
private Handler mHandler=new Handler(); // run on another Thread to avoid crash
private Timer mTimer=null; // timer handling
#Nullable
#Override
public IBinder onBind(Intent intent) {
throw new UnsupportedOperationException("unsupported Operation");
}
#Override
public void onCreate() {
// cancel if service is already existed
if(mTimer!=null)
mTimer.cancel();
else
mTimer=new Timer(); // recreate new timer
mTimer.scheduleAtFixedRate(new TimeDisplayTimerTask(),0,INTERVAL);// schedule task
}
#Override
public void onDestroy() {
Toast.makeText(this, "In Destroy", Toast.LENGTH_SHORT).show();//display toast when method called
mTimer.cancel();//cancel the timer
}
//inner class of TimeDisplayTimerTask
private class TimeDisplayTimerTask extends TimerTask {
#Override
public void run() {
// run on another thread
mHandler.post(new Runnable() {
#Override
public void run() {
// display toast at every 1 minute
Toast.makeText(getApplicationContext(), "Notify", Toast.LENGTH_SHORT).show();
}
});
}
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);//load the layout file
startService(new Intent(this,MyService.class));//use to start the services
}
}
Also add this code in your manifest file
AndroidManifest.xml
<service android:name=".MyService"
android:enabled="true"/>
Try to create a Timer object.Then use the scheduleAtFixedRate(TimerTask) to repeat the Toast message.
You can just make a looping thread which contains your code.
Like this:
public class Toaster extends Thread{
public void run(){
//Your code to loop
thread.sleep(60000)
}
}
Hope it helps!
I'm having serious problems when showing a ProgressDialog while a service is getting ready... The service takes time to get ready as it's a bit heavy, so I want to show the ProgressDialog meanwhile it's started.
The thing is that it shows the ProgressDialog right before the next activity starts... I really don't find what it is...
package org.pfc;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
public class ConnectActivity extends Activity {
// FIELDS------------------------------------------------------------------
protected LocalService mSmeppService;
private ProgressDialog progressDialog;
private Thread tt;
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder service) {
// Gets the object to interact with the service
mSmeppService = ((LocalService.LocalBinder) service).getService();
}
public void onServiceDisconnected(ComponentName className) {
// This is called when the connection with the service has been
// unexpectedly disconnected -- that is, its process crashed.
// Because it is running in our same process, we should never
// see this happen.
mSmeppService = null;
}
};
// For getting confirmation from the service
private BroadcastReceiver serviceReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
Log.i(TAG, "receiver onReceive...");
if (progressDialog.isShowing())
progressDialog.dismiss();
// Change activity
Intent groupsActivityIntent = new Intent(ConnectActivity.this,
GroupsActivity.class);
startActivity(groupsActivityIntent);
}
};
// METHODS ----------------------------------------------------------------
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (LocalService.isRunning) {
// TODO start ListActivity
Log.i(TAG, "Starting GroupsScreen");
Intent i = new Intent(ConnectActivity.this, GroupsActivity.class);
startActivity(i);
} else {
setContentView(R.layout.connect_screen);
// Add listener to the button
Button buttonConnect = (Button) findViewById(R.id.button_connect);
buttonConnect.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
processThread();
}
});
}
}
// PRIVATE METHODS --------------------------------------------------------
private void processThread() {
progressDialog = ProgressDialog.show(ConnectActivity.this, "",
"Loading. Please wait...", true, false);
tt = new Thread() {
public void run() {
// Register broadcastReceiver to know when the service finished
// its creation
ConnectActivity.this.registerReceiver(serviceReceiver,
new IntentFilter(Intent.ACTION_VIEW));
// Starts the service
startService(new Intent(ConnectActivity.this,
LocalService.class));
Log.i(TAG, "Receiver registered...");
}
};
tt.start();
}
}
The service executes by the end of the onStart method this:
// Send broadcast so activities take it
Intent i = new Intent(Intent.ACTION_VIEW);
sendOrderedBroadcast(i, null);
So the onReceive method runs and we go to the next activity
The problem is that you are not running ProgressDialog in a UI thread.
Add a handler that will handle messages in your UI thread.
private static final int UPDATE_STARTED = 0;
private static final int UPDATE_FINISHED = 1;
private Handler handler = new Handler(){
#Override public void handleMessage(Message msg) {
switch (msg.what) {
case UPDATE_STARTED:
progressDialog = ProgressDialog.show(ConnectActivity.this, "",
"Loading. Please wait...", true, false);
break;
case UPDATE_FINISHED:
if(progressDialog.isShowing()){
progressDialog.dismiss();
}
break;
}
}
};
private void processThread() {
Message m = new Message();
m.what = UPDATE_STARTED;
handler.sendMessage(m);
//Your working code
m = new Message();
m.what = UPDATE_FINISHED;
handler.sendMessage(m);
}
good luck!
I am writing a simple service application, below is the code of Activity and Service..,when I am calling startService(), and stopService() its working fine for the one time,in my case it has to give notification..from next time onwards if call again startService(), and stopService() its not giving desired results...
---------- this is my activity class -------------
package com.mypack.serviceex;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
public class serviceex extends Activity implements Button.OnClickListener{
/** Called when the activity is first created. */
Button bt1,bt2;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
bt1 = (Button) findViewById(R.id.Button01);
bt2 = (Button) findViewById(R.id.Button02);
bt1.setOnClickListener(this);
bt2.setOnClickListener(this);
}
#Override
public void onClick(View v) {
if( v == bt1)
{
Intent i = new Intent(serviceex.this,myservice.class);
Log.i("err","onClick(View v....");
startService(i);
}
else if(v == bt2)
{
Intent i = new Intent(serviceex.this,myservice.class);
Log.i("err","else if(v == bt2)........");
stopService(i);
}
}
}
--------- this is my service -------------
package com.mypack.serviceex;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;
public class myservice extends Service
{
private NotificationManager nmgr;
public void onCreate()
{
super.onCreate();
nmgr = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
Log.i("err","onCreate..........");
Thread th = new Thread(null,new incls(),"service...");
}
public void onStart(Intent intent,int sid)
{
super.onStart(intent, sid);
Log.i("err","onStart........");
}
public void onDestroy()
{
super.onDestroy();
Log.i("err","onDestroy..........");
displayMessage("Stopping Service");
}
public void displayMessage(String str)
{
Log.i("err.","displayMessage.....");
Notification nf = new Notification(R.drawable.icon,str,System.currentTimeMillis());
PendingIntent pi = PendingIntent.getActivity(this, 0, new Intent(this,myservice.class), 0);
nf.setLatestEventInfo(this, "Service...", str, pi);
nmgr.notify(R.string.uid, nf);
}
private class incls implements Runnable
{
public void run()
{
Log.i("err","public void run()..........");
System.out.println("In Runnn");
}
}
#Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}
}
None of your methods are #Overrideing the class methods. You have to annote them with #Override. Also, on 2.1 you should use onStartCommand() instead of onStart(). And also note that calling startService() multiple times will only call onCreate() once