Develop Reference

ObservableObject updateValue doesn't reach the right instance after startActivity

I have a basic Activity which mainly allows the user to change settings and save them. I also have a BroadcastReceiver which is launched on SMS_RECEIVED.
The main point of the app is to vibrate whenever a certain message is received until the user taps a button to make it stop. The activity is only there to allow the user to change settings and press the "Stop" button.
In my onReceive method (BroadcastReceiver), I get the content of the last message received and make the phone vibrate if the message is equal to a certain string. All of that is working perfectly, the problem is when I want to make it stop. Right now, I'm trying to make a "Stop" button appear in the Activity when the phone starts vibrating.
I understand that UI elements should remain in the Activity and so what I'm trying to do is communicate between the Activity and my BroadcastReceiver. I've found here how to do that with an Observer. The problem though is that I want the app to function at any time, even at boot time. It's very easy with a BroadcastReceiver but since it requires the Activity to be shown to allow the user to stop the vibration, I have to start the activity if it isn't started already.
So what I do is this:
Intent i = new Intent(context, MainActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
i.putExtra("SMSReceived", true);
context.startActivity(i);
ObservableObject.getInstance().updateValue(true);
The problem is, when there is no instance launched, it creates a new one and sends the extra boolean correctly but the updateValue method doesn't seem to get called at all (due to the previous instance I suppose?) and inversely, when there is an instance launched (in the background) the extra boolean doesn't get passed and the updateValue method gets called correctly.
I suppose I could just launch the Activity on boot and immediately put it in the background but it could cause problems if the user closes the application, at which point it would simply stop working until the user started it again since the Observer would have no instance to send data to.
Do you guys have any idea of what I could do to solve my problem?
If it's not clear I can try to explain further.

ANDROID: open an URL in external browser, while continuing the application

In the starting activity of my app I show a dialog to user and ask if he wants to see some contents in my website or not.
If he clicks No, the dialog disappears and I call continueActivity() to do some process and go from current activity to MainActivity.
If he click yes, I want to open the webpage in the external browser and again I call continueActivity() to do some process and go from current activity to MainActivity.
The problem is in positive state. This is my code in positive state:
Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.aaa.ir"));
startActivity(browserIntent);
continueActivity();
Because of calling continueActivity(), the external browser can't open and if I don't call continueActivity(), the URL opens in the external browser and the app sticks in the current activity.
So how could I open the URL and at the same time, continue the process and go to other activities.

I usually use
startActivityForResult(browserIntent, BROWSER_REQUEST);
and override onActivityResult(int reqCode, int resultStat, Intent intent)
if(reqCode == BROWSER_REQUEST) {
continueActivity();
}

Once you call startActivity, your current Activity will follow through the exit of the Activity lifecycle. This is unavoidable.
If you have processing you want to continue in the meantime, you should consider a Service. If you want the App to return to its current state, you need to store relevant data and load your Activity to its previous state (or next intended state).

in both ways ContinueActivity is opening. i don't know you architecture. You could just add to intent some extra like
intent.putBoolean("openExternalLink", dialogResultHere);
Then in continueActivity you will got this intent like
getIntent().getBoolean("openExternalLink")
also dont forget to delete this option, otherwise you will open browser each time after Activity recreation (screen rotation, minimize, etc.)
getIntent().removeBoolean("openExternalLink");
P.S. signatures of methods could be littlebit different, but general idea is here

Android intent service onClick, or start new activity and then Asynctask

Many times in android apps, users click a button/view and start a new activity, where the new activity pops up in front of what the user was previously looking at, and loads data.
Would there be any difference from a user perspective if the data started loading (from network or disk or both) when the user clicked the button before the next activity started. And then that data was returned to the new activity in a broadcast receiver.
This is compared to starting the process in the oncreate of the activity. Assuming these network and i/o processes only take milliseconds either way, would it make a difference to the user if the methods were started in onCreate of the new activity, or started in the old activity onClick.
First way, starting I/O and changing views after I/O finishes
//first activity
public void onClick(View v){
startActivity(new Intent(this, NewActivity.class);
}
//NewActivity.class
onCreate(Bundle mBundle){
super.onCreate(mBundle);
setContentView(R.layout.mView);
mObject = networkCall(); //after network call, the view objects in this layout will reflect data from the network call
}
second way, starting the I/O in the first activity
//first activity
public void onClick(View v){
IntentService networkCall = new IntentService();
//start network call
startActivity(new Intent(this, NewActivity.class);
}
//second activity on create just sets the view and also broadcast receiver
My GUESS is that in the split second that it takes for the activity to pop up, the data from the intent service could become available. But at the same time, passing data via intent could take just as long making the benefits marginal
Insight appreciated

In my experience the onCreate() of your new activity is called almost instantly from when you call startActivity(). The new activity doesn't show up right way because it has to take time to render your layout.
You could play around with timings yourself by using the Log.d() function. Something like Log.d(TAG, "This happend at: " + System.currentTimeMillis()); at different points in your code to see when things happen. Watch the LogCat while your apps runs and you can decide for your self which way is better.

recover an app from stack or app in background

I have a small application with two activities.
The first activity has a button, pressing this button opens a second activity (the first is paused)
This second activity launch notification.
With the notification released, leave the application by pressing the "home" button and let the application on the stack or in background.
When I click on the notification, I want the application to retrieve the activity that was on the screen.
I am recovering the application using the package name:
Intent intent = null;
PackageManager manager = getPackageManager();
try {
intent = manager.getLaunchIntentForPackage("hello.com.vierco.pruebas");
if (intent == null)
throw new PackageManager.NameNotFoundException();
intent.addCategory(Intent.CATEGORY_LAUNCHER);
intent.putExtra("hola", notificationData);;
} catch (PackageManager.NameNotFoundException e) {
}
I get retrieve the application, but always opens the activity number "one" because is reopening.
Someone can tell me how I can retrieve the application? retrieve it from the stack, not open it again. there is any intent?
Wear two days trying without success, I have also searched many forums but without success
A practical example would be grateful because I'm going slightly mad

Try to start intent, if crash, start another intent

I am developing an app were i need to use some sort of method to handel two different intents from a click of a Button. The first is only sometimes able to start without crashing the app. Therfore i need to start another intent were the app normally would have crashed.
Better explained do I need some sort of method that launches another intent, if the 1. intent can not start a new activity, then start the 2 intent.
I really appreciate some sort of formula, instead of a link or reference.

You are looking for a try catch block.
try
{
startActivity(intent);
}
catch(Exception e)
{
startActivity(another_intent);
}

Try/Catch in your code. You can then launch another intent if the first one fails.
If your application is crashing, you should sort this out. You wont be able to start another intent if the application crashes though, because the Applications Process has been killed by the OS. You will need to detect if you can launch the activity, otherwise launch another.

Fix the crash, then implement some switching logic based on what used to be causing a crash.