Android GCM messages activity - reloaded when ever the activity starts - google-cloud-messaging

Question

I am writing an app which has GCM in it. I am not trying to compete with Whatsapp. It should just a sort of bulletin board between all those who use this app.
The app is opened with a menu of buttons and one of them directs the user to the Messages activity.
As long as you stay on this activity, the messages are there and everything works as it should be.
But, if I go back to the menu activity and then go back into the messages activity, then all messages are gone and are not shown.
I am using ListActivity for the messages and the onCreate function, destroys the current list each time it is read.
My question is, how can I return to the messages activity without loosing them? I want to have it as in Whatsapp, when you go into Whatsapp the messages are always there!
I thought of saving the messages list into a file and then read it (or let's say the last 40-50 messages) anytime the onCreate is called. Is this a good solution? Is there any solution without saving the list to a file?
Here is some of my code inside the messages activity:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_msg_main);
Intent in = getIntent();
username = in.getStringExtra("username");
password = in.getStringExtra("password");
nickname = in.getStringExtra("nickname");
messages = new ArrayList<Message>();
txtNewMsg = (EditText) this.findViewById(R.id.text);
adapter = new MessagesAdapter(this, messages);
setListAdapter(adapter);
registerReceiver(mHandleMessageReceiver, new IntentFilter(DISPLAY_MESSAGE_ACTION));
}
private final BroadcastReceiver mHandleMessageReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String newMessage = intent.getExtras().getString(EXTRA_MESSAGE);
// Waking up mobile if it is sleeping
WakeLocker.acquire(getApplicationContext());
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");
String currentDateandTime = sdf.format(new Date());
Spanned newMessageDate = Html.fromHtml("<small><i><font color=\"red\">" + currentDateandTime + "</font></i></small>" + " " + "<small><i><font color=\"blue\">" + nickname + "</font></i></small>" + "<br />" + newMessage);
addNewMessage(new Message(newMessageDate, true));
WakeLocker.release();
}
};
#Override
protected void onDestroy() {
if (mRegisterTask != null) {
mRegisterTask.cancel(true);
}
try {
unregisterReceiver(mHandleMessageReceiver);
GCMRegistrar.onDestroy(this);
} catch (Exception e) {
Log.e("UnRegister Receiver Error", "> " + e.getMessage());
}
super.onDestroy();
}
void addNewMessage(Message m)
{
messages.add(m);
adapter.notifyDataSetChanged();
getListView().setSelection(messages.size()-1);
}
The code includes: onCreate, BroadcastReceiver (GCM receiver), onDestroy and addNewMessage which adds the new message to the messages list.
Thanks for any help!
AJ

Answer 1

Create database with message table and users table which will store the message and users details.
Now whenever new message is come store in database and then when you open the app load limited message from table. If the app is open and message is come first store in your database and add to your list object and invalidate your listview.