Develop Reference

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);

Exit an android app

How to close an android app if more than one activity is in active state?

A blog post entitled Exiting Android Application will show how to exit an Android app:
When the user wishes to exit all open activities, they should press a button which loads the first Activity that runs when your app starts, in my case "LoginActivity".
Intent intent = new Intent(getApplicationContext(), LoginActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
intent.putExtra("EXIT", true);
startActivity(intent);
The above code clears all the activities except for LoginActivity. LoginActivity is the first activity that is brought up when the user runs the program. Then put this code inside the LoginActivity's onCreate, to signal when it should self destruct when the 'Exit' message is passed.
if (getIntent().getBooleanExtra("EXIT", false)) {
finish();
}

I got an easy solution for this problem
From the activity you press the exit button go to the first activity using the following source code. Please read the documentation for FLAG_ACTIVITY_CLEAR_TOP also.
Intent intent = new Intent(ExitConfirmationActivity.this, FirstActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
Now overide onResume() of the first activity using finish()

The answer is simple: You really do not need to 'close' an Android application. If no activity is shown any more, the system will kill the process after some time. The users can close activities by pressing the 'back' button. Reto Meier explains it pretty well here:
http://blog.radioactiveyak.com/2010/05/when-to-include-exit-button-in-android.html

You might also want to read this thread; it is very helpful to say the least: Quitting an Android application - Is it frowned upon?

Well, you shouldn't close your applications, as the system manages that. Refer to the posts/topics in the other answers for more information.
However, if you really, really want to, you can still call System.exit (0); like in any other Java application.
EDIT
ActivityManager actmgr = (ActivityManager) this.getSystemService (Context.ACTIVITY_SERVICE);
actmgr.restartPackage ("com.android.your.package.name");
I remembered something. I was trying to use this code to restart my application, but it only managed to kill my app. You can try it and see if it works for you.

I asked a similar question a couple of weeks back. Do go through the answers and comments for more perspective and possible solutions.
IMO quitting an application depends on what your application does and the user expectations. While I understand the rationale on not having a quit button I also do believe that it's a choice that the application designer has to make based on the situation.

Once your last Activity looses focus, Android will unload your process according to the current system needs / free resources.
You shouldn't really care about that - just use the lifecycle onStart, OnStop etc... to manage your state.

If you want to exit from one Android activity, this will bring you back to the previous activity or another activity from a specific place in current activity.
finish();
System.exit(0);

Sending a running application to background programmatically

Is it possible to send a activity into background programmatically in android?
I am creating a prank application that plays funny sounds after a specified time (input by the user). And I don't want the application to be visible when playing that sound and also the display should be dark.

Yes.
You can use either:
boolean sentAppToBackground = moveTaskToBack(true);
if(!sentAppToBackground){
Intent i = new Intent();
i.setAction(Intent.ACTION_MAIN);
i.addCategory(Intent.CATEGORY_HOME);
this.startActivity(i);
}
More information here: http://developer.android.com/reference/android/app/Activity.html#moveTaskToBack(boolean)
Or simply:
Intent i = new Intent();
i.setAction(Intent.ACTION_MAIN);
i.addCategory(Intent.CATEGORY_HOME);
this.startActivity(i);
According to Romain Guy a Android Framework Engineer, "You cannot simulate a press on the Home key.". So beware...
Check: http://osdir.com/ml/Android-Developers/2010-03/msg01887.html
Updated this answer according to: moveTaskToBack(true) returns false always

This function ultimately works for you
moveTaskToBack(true)
Or download source code . Android minimize app programmatically

Maybe play the sound from a service instead?

To expand on the answer by #ns476, the reason you should play it from a service is that any Activity that is no longer in the foreground can be killed at any time by the OS. Please review the activity lifecycle.

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.

Opening browser activity, but prevent it from being in the activity history

I'm working on an app that launches the browser activity to perform a Twitter OAuth authorization. This process uses a callback url which will re-launch the activity that started the browser activity in the first place.
My problem is that the browser pages remain in the history stack and when the user then clicks back from the preferences activity that launched the browser in the first place, they don't go back to the app's main activity, but instead are brought back to the browser. I've tried adding flags to the launching intent to prevent history and reset on clear, but it doesn't seem to work when running on my phone, only on the emulators.
Here is the code I'm using to launch the browser activity:
Intent webIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(authUrl));
webIntent.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
webIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
webIntent.addFlags(Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);
ctx.startActivity(webIntent);
Anyone have any idea what might be wrong?

Set the activity flag to Intent.FLAG_ACTIVITY_CLEAR_TOP after starting it. This way, the task will be deleted form the app stack so your main activity remains the top one on every new launch:
ctx.startActivity(webIntent);
browserIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

call
finish();
after
ctx.startActivity(webIntent);

Hi i have the same problem at the moment. I think the solution is to start the activity you want to return to with a special flag:
Intent intent = new Intent(this, acticityToReturnTo.getClass());
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
startActivity(intent);
The problem is that is does not work (on 1.6 at least).. But maybe someone finds a solution for this. I think FLAG_ACTIVITY_CLEAR_TOP is exactly what we.

I found that Intent.FLAG_ACTIVITY_NO_HISTORY works only if the browser was not running before. If I restart Android and run my app which call browser everything work well. But when I start browser before my app, browser will stay in history.
Here is related question also, but with no really working solution
How can I do that in Android. Activity -> WebBrowser -> Acrivity, but Press Back not see the WebBrowser