I have a service that is working in the background - SERVICE A.
When I open an activity - ACTIVITY A, I want this service to change the text that is displayed on the editText field of this ACTIVITY A.
I thought that maybe if I get the context of the opened activity then I will be able to use and work on its Views. Is it possible?
Also a related question:
If I don't have the name of the field, can I use some loop to run and search for all the views in the activity and get its properties?
It seems like a less direct method would be preferred to getting this, rather than have the activity be directly updated by the service. In fact, in general Service/Activity communications are best handled in one of the following ways:
MessageHandlers- Basically, one can send a message to the other, which in turn the other sets the actions of the text.
BroadcastReceivers (LocalBroadcastReceiver is also okay)- One part sends a broadcast message to anyone listening, the other sets up a listener for that message. An Intent is passed, which can contain the message.
I would suggest that you use the second. The application sends a broadcast to the service upon opening, and the service returns a broadcast to pass the requested data to the Activity.
See also the Service docs from the Android SDK.
1 save the string in preferences from service (see this : https://stackoverflow.com/a/12074248/4647577 )
2 retrieve the string when activity is created and set it to edittext
In your question you said that you want to show the string when you open the activity , so the 2 steps above will do the job .
For better performance you can repeat the second step in onresume();
Related
The problem is only when my activity already shown it begins updates and it look no good. How it works: in onStart of activity I send cmd to service to get update data, also I register brodcast listener there. I want to prepare received data from service to show before activity appears. How to do that? Thanks.
How it works now: when I back from another activity first I see old data and then it changes (very fast but you can see it) to new.
if you want to setup things before your activity is shown you need to do things in the onCreate method instead of onStart method.
further informations in android documentation
When you send the command to the service to update your data, you should change the views in your Activity to show loading indicators, or a blank view, or whatever you want the user to see until the Broadcast comes in that your new data is ready. Then you shouldn't need to worry about old data being visible.
I need your help because I want to write an Android app which works like this: when I tap the app launcher, I show an activity in which the user has to insert some data, like his name ecc. These data are passed to a background service through an intent and when the service starts I show a notification. When I click on the notification I show another activity in which the user can press a button to stop the service. Everything works fine but I would like that, if I tap again the app launcher but the service is active, the user didn't see the first activity (the one in which he has to insert the data), but the last one in which there is the button to press to stop the service. I don't have a clue of how to do. Can you help me please? Thanks.
Do you really need two Activities for these use cases? You can have just one Activity and two Fragments, one for starting the Service, and one for stopping. In your Activity's onCreate() method check if the Service is running and inflate the right Fragment dynamically.
I have an IntentService that is run from time to time to notify users to add something. I do not want to send notifications if the users are in my app (in one of the activity). Is there a simple way to achieve it?
One way is by having a boolean set in MyApplication and setting it true in onStart/onStop or onResume/onPause. Is this the right way?
You could make all of your activities subclass a custom activity that has a static variable that keeps track of wether or not an activity is on screen.
Like: Android: how do I check if activity is running?
However, I would use an int instead of a boolean, just incase there is some kind of race condition between an onResume and an onPause from one activity to the next.
I am designing an app that is used for emergency alerts. The alerts come from a server and a connection to that server is maintained in service.
If the service receives an emergency request from the server it checks to see if a specific activity is open. If it is it lets it know an emergency has been triggered and the activity launches a dialog activity with some options. It then handles results from this new dialog activity.
However, if the service notes that the activity is NOT open I want it to launch the dialog anyway. I know that this isn't good practise but because of the importance of this emergency I don't want to rely on Notifications (which are already in use if the activity is closed to let the user know that the app is still listening for emergencies).
What currently happens is that the below code is executed in the service and the dialog launches. However, the 'main' activity (the only other activity in the app) also opens behind the dialog. What I really want to happen is that either...
1) The service launches the main activity which then opens the dialog so that I can easily capture the results.
2) The service launches only the dialog activity and I use a broadcast receiver to capture results from this activity.
1 would use the mechanics that already exist for capturing results from an activity. However I don't like the idea of chaining the activities together in this way.
2 means I can ignore the main activity all together (because I don't really need it in this instance) but seems more of a get around.
What I am really asking is two things. What is best practise given my circumstances and how do i achieve number 2? Here is the launch code in my service. Notification in this code is referring to the dialog activity that will open.
if (MainActivity.isActivityInUI) {
//Dealt with by activity
sendMessageAlert(message);
} else {
//Launch dialog directly from service
Intent notification = new Intent(this,
EmergencyNotificationActivity.class);
Bundle args = new Bundle();
args.putString(MobileMessage.EXTRA_LOCATION_NAME,
message.locationName);
args.putString(MobileMessage.EXTRA_ID,
String.valueOf(message.id));
args.putDouble(MobileMessage.EXTRA_LATITUDE,
Double.valueOf(message.latitude));
args.putDouble(MobileMessage.EXTRA_LONGITUDE,
Double.valueOf(message.longitude));
//and the flag to let the notification know this is from a service...
args.putBoolean(EXTRA_FROM_SERVICE, true);
notification.putExtras(args);
//add flag because this is being called from outside of an activity
notification.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK |ActivityInfo.LAUNCH_SINGLE_INSTANCE);
startActivity(notification);
I think instead of trying to show a dialog without visibly showing an Activity, you should consider launching an Activity that is themed like a Dialog. Just apply the following theme: http://developer.android.com/reference/android/R.style.html#Theme_Dialog (or similar themes) to your EmergencyNotificationActivity. You probably would have to tweak your class to behave like a dialog instead of launching one (which I am assuming is what you're doing currently).
This method would also allow you to not have to check if an Activity already exists.
Is there any way I can go from one activity to another and delay the display of the screen on the target activity?
What I want to be able to do is to allow the target activity to fetch its required data but not to display anything until does.
I want the screen of the source activity to still be visible until I am ready with the data in the second activity.
Specifically, I am using an AsyncTask to fetch the data.
I know I could fetch the data in the source activity and then send it on to the target activity but this is not viable in our case.
Edit: More Info:
The whole reason I want this is because I am trying to change the structure of certain parts of the current code.
At present the way it works is the the first activity gets the data and then sends it to the second activity as a bundle.
This created problems when the second activity could be invoked from multiple places. It resulted in loads of duplicate code.
So, I decided to move the fetching of the data into the target activity thus cutting out any need for repeating code.
it also makes more sense for the activity to fetch its own data rather than relying on something else sending it.
You should first make a service that runs your async task. Then, start the service from your first activity with startService(new Intent(this, UpdaterServiceManager.class));
When the task ends in the service, start the second activity.
Click here for an excellent service tutorial.
Try to use service for this purpose.