Develop Reference

Android / Xamarin, Open file with intent and close app after back button pressed

I have a problem with a feature of my application.
I need to open external files to display them like .jpeg or .xls for example. For that I use Intents to open them with the default system application and it works fine.
But in a case where we will first open a document, for example a photo. this will display in the default app and then I go back and forth in my app. Everything is OK
But then I'm going to open another standard .xls document, it'll open the document in the appropriate application and going back will show the opened image first and not my application again.
I don't understand why it happens like this.
What I would like is that when we do previous in a file viewer app, the app quits and doesn't stay in the ActivityManager.
Is it possible ?
I have already tried some intent flags but without success.
My code here :
Android.Net.Uri fileUri = FileProvider.GetUriForFile(Android.App.Application.Context, "com.app.fileprovider"
, file);
Intent intent = new Intent(Intent.ActionView);
intent.SetData(fileUri);
intent.AddFlags(ActivityFlags.GrantReadUriPermission);
intent.AddFlags(ActivityFlags.NewTask);
intent.AddFlags(ActivityFlags.NoHistory);
Android.App.Application.Context.StartActivity(intent);
return true;
Thanks a lot for the help
Max B

SO !
My bad, It was not a real problem.
It was a design error.
Indeed during my call of my function to call the intention I linked my opening event without then unbinding it. So that with each call I recalled X times my file opening function without ever destroying my variable or my variable instance.
The Intent Works Well
Thanks for the comments

Can I start an activity as a new Application or outside my app?

I am trying to help my users to turn on their GPS like this:
Intent gpsOptionsIntent = new Intent(
android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivity(gpsOptionsIntent);
The problem is that it opens the android settings as it was a view from my app, but I want to open it as a new application (android default settings aplication), in other words, outside my app.
Does anyone know how to accomplish what I want?
Thanks!

The code you are executing shows a new activity "on its own app process", if the activity you are calling is not in your application project it mean's that is not in your application context, so my thought is that just because you go back and fall down in the last activity shown you may think is in your app, but that's not the case, the activity is running on it's own process and because of the back stack you are going back to your previous activity.
Hope this Helps.
Regards!

The problem is that it opens the android settings as it was a view from my app,
No it doesn't. It's starting an Activity which is part of the Android Settings app.
but I want to open it as a new application (android default settings aplication), in other words, outside my app.
That's exactly what is happening - it's just opening the Activity which deals with the settings for Location Services rather than opening the default Settings root page.
Don't confuse the generic terms 'app' and 'application' with Android classes such as Application and Activity.
Android is meant to be modular - even though it looks like the Activity which is started with your code is part of your own 'app', in reality what happens is an instance of the native Settings app is created and the Location Services Activity is displayed. This happens entirely outside of your app.

As mentioned in this answer and comment, you need to add intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
Intent gpsOptionsIntent = new Intent(
android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
// add the following line
gpsOptionsIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(gpsOptionsIntent);

Getting data from intent

I am little confused about getting data from intent of an activity, here is what I am trying to do.
I am opening my first activity
I press home button and my activity(application) goes in background
I go to download folder and select one doc file it gives me Open with feature with my application in list.
I select my application.
Now instead of getting resume it calls create method of activity(I think its ok because second instance of my app(activity is created))
Here I try to get data from intent using intent = activity.getIntent();
But I dont get anything(getting null expecting path of this doc)
If I first open my app with Open with feature(No background activity right now) I get file path successfully but when I pres home button and my app goes background again and if I press my app from application list again intent has same data(expecting null in this case.)
What I am trying to achieve:-
I am simply trying that if user is coming from application list intent data should be null and if he is coming from Open with function then he intent data should be path of file.
One more thing I am trying this behaviour in Appcelerator Titanium but as this is native behaviour(handling life cycle of activity and I can do this in titanium) but having no luck.
Thanks.

I some what manage this by giving my activity as 'singleInstance' in manfiest file. So now I can be sure that at a time same instance is running.
Now for handling intent data I am registering onNewInstance method. By using this intent data is get affected everytime when I comes from background or when when I select any file to open with my application.
Thanks.

Android Launching or bringing to front another application via Intent

Im having trouble getting this to work, here´s a quick overview of the idea.
First, I cant change the logic behind this, it was a specific requirement from the customer, I realize that with any tool such as AnyCut it could be bypassed but that doesnt matter really.
My customer offers a suite of apps, the idea is that all applications bellonging to the suite would be launched from a "Dashboard app", so that I only show the Dashboard app in the main launcher and not all app icons.
Lets take two Apps to get the idea solved. The Dashboard App (A) and the Recieving App (B).
I want to establish an intent filter (I think) on app B so that whenever I go into app A, and click the app B icon the app will be either launched or started from where it let of (brought to front).
Is this even possible? If so, how can I do it? I managed to get it to launch by specifically launching one activity in the app using:
Intent i = new Intent();
i.setClassName("PACKAGE_NAME","SPECIFIC_CLASS");
startActivity(i);
But that isnt the behaviour that I want, as it always starts app B in the same spot.
Thanx in advance,
Stefano
Edit: Added some new information. I was taking a look at the DDMS.
If I launch the application from scratch through the main Android launcher the intent is exactly the same as when I leave the home button pressed and then only bring the app to front, what ever activity im in. So I was trying to reproduce, unsucsesfully until now, this intent.
INFO/ActivityManager(1292): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.example.package/.uiPackage.Activity}
This is how AnyCut does it
Intent { act=android.intent.action.VIEW flg=0x10000000 cmp=com.example.package/.uiPackage.Activity bnds=[125,242][235,360]}
Any idea how I could go about creating that exact same intent? I cant even find that flag in the Intent API.

Figured it out, this is how I did it.
Intent i = new Intent();
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
i.setAction("android.intent.action.VIEW");
i.setComponent(ComponentName.unflattenFromString("com.example.package/com.example.package.activityName"));
startActivity(i);

I'm not quite sure I'm following the expected results you want to see, but the following would launch the app from the dashboard and remove the dashboard from the activity stack leaving the selected app running:
Intent i = new Intent();
i.setClassName("PACKAGE_NAME","SPECIFIC_CLASS");
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
I believe this should start the app as if you were starting any other app.
Please add more information on your logic if this is not what you are looking for.

I think that when you switch activities android's default action is to sort of pause or hold the activity in its state the user left it in last. I know there is a way to make it so that the state is not saved when switching activities but I cant remember it off the top of my head.

Android: Starting An Activity For A Different Third Party App

I'm working on an app and I want to integrate the Last.fm app into it. Basically, when someone is looking at an artist in my app, I would like to have a button that they can tap to open up Last.fm application with the artist's information.
This intent works, but it loads a menu asking which app I would like to use (Browser or Last.fm):
Intent i = new Intent();
i.setData(Uri.parse("http://last.fm/music/" + headliner));
i.setAction("android.intent.action.VIEW");
startActivity(i);
However, I just want to start the Last.fm app and skip the dialog asking which app to use, I thought maybe using the setPackage() method would work like this:
i.setPackage("fm.last.android");
But it causes the app to crash:
android.content.ActivityNotFoundException: No Activity found to handle Intent { act=android.intent.action.VIEW dat=http://last.fm/music/Rihanna pkg=fm.last.android }
Is it possible to just start the Last.fm app? Here's a copy of Last.fm's AndroidManifest.xml for reference.
Thanks for reading,
Tony

Yes, it's possible but you need to know the correct component name. Launch the last.fm app regularly and check the logfile for the cmp=... information that's been used when the app is started. Use this as well in your app then.
I start the Z-DeviceTest app from the market from within my app without a problem like this:
final Intent intentDeviceTest = new Intent("android.intent.action.MAIN");
intentDeviceTest.setComponent(new ComponentName("zausan.zdevicetest","zausan.zdevicetest.zdevicetest"));
startActivity(intentDeviceTest);
in my case the info I took from the logcat was:
// dat=content://applications/applications/zausan.zdevicetest/zausan.zdevicetest.zdevicetest
// cmp=zausan.zdevicetest/.zdevicetest
in order to know how to start the app with the right component/class... do the same for the last.fm app
Edit:
I've tested to launch Last.fm from my own app, and this works fine without any errors:
final Intent intentDeviceTest = new Intent("android.intent.action.MAIN");
intentDeviceTest.setComponent(new ComponentName("fm.last.android","fm.last.android.LastFm"));
startActivity(intentDeviceTest);