I have a security program, so i need to quit the application when the HOME button pressed. But I know the HOME button action cannot be implemented.
Then, I know that I can use
android:noHistory="true"
to do it. But I have used
startActivityForResult(intent, 0);
to call a new activity. When the activity called back by
this.setResult(RESULT_OK, intent);
this.finish();
The original activity has already quit.
How can I quit the application when the HOME button pressed, but the startActivityForResult will not quit the activity?
Don't quit the application - that's not how android works.
Instead, in a desired situation, perhaps onPause(), destroy the security credentials that let your app function. On the next run or resume, the user will have to re-authenticate.
Perhaps you can use onUserLeaveHint() as an indication that you should finish(). This is called when the user intentionally leaves your activity (ie: by pressing HOME key)
As a general rule, you shouldn't be quitting your app like this. It breaks the intuitive workflow most people expect when using an app. However, if you really want to do this, override onPause() and onStop() and implement the code to quit in those. Remember to call super() in your overridden method.
Related
How to complete the application when pressed buttons Home and Back? Provided that in my memory holds many pictures.
When pressed on the Back button - application restarts... When pressed on the Home button - quit application, but when it restart - does not start Splashstsreen.
Hard to see without code but it sounds like your activity is resuming rather then starting from scratch (as it should behave). It sounds like it's behaving correctly in that case. If you insist in wanting your application to truly quit after the back button is clicked perhaps you can override onBackPressed() then have your Activity call its finish() method.
I don't think it's good programming practice to fiddle and interfering with the activities lifecycle. It's the OS responsibility to manage the lifecycle, including pause and finish activities.
Instead you should use other methods to handle your problem with not showing splash screen, these methods are onResume and maybe also onStart(). Also you should get familiar with the activity lifecycle(link submitted by #ss1271).
Press Home will let the activity to enter onPause(). however, if you insist to quit the application when press HOME, which is obviously not a good practise, you can do like this:
Override onPause() and onBackPressed()
add finish(); to these methods.
I am sure by adding finish(); to onBackPressed() will quit the app when Back button pressed, but I haven't tried on Home.
Please refer to Activity Lifecycle for more info.
if a user tapped the home button and open the app after that, how to not allow back? eg don't allow users to go back to screens that they seen before tapping the home button. It should be treated as a new session
This sounds like a bad idea, as it blatantly goes against the Android task/navigation guidelines.
The user expects to be able to back out to the previous screen after resuming a task... and preventing it will potentially piss off a lot of users.
Please, please, please read these documents before you risk destroying the user experience.
App structure
Navigation
Tasks and back stack
The home button cannot be overridden nore should it, if you dont want the user to go back to the activity they left when the home button was clicked then on the on pause of the activity just pop the backstack to where you want to be.
see this answer
If you want to end your Activity once it is no longer visible then finish your activity in your Activities call to onStop().
#Override
protected void onStop() {
super.onStop();
this.finish();
}
This will finish your Activity with no chance of onRestart() being called. Be careful with this method because users expect to resume the app instead of having to start over, but there are cases where this would be the accepted protocol. See more on Navigation and the Activity LifeCycle.
Edit:
Also see the question Android-Quittings an application - is that frowned upon? specifically this answer.
When you press the home button, what does it do by default?
I want to keep what it does by default, but make sure it ends my music as well.
For example:
public void onBackPressed() {
return;
I disabled my back button.
I want to make it so the home button does what it does, but i want to call my
this.stopService(new Intent(this, Music.class));
in the method too.
It is not possible to override "Home" key press just like you did for Back button press. In fact you're not supposed to over ride home key press because user presses Home key to quickly come to the launcher.
Even if you try to override onKeyDown(), you'll see that Home key press will not invoke this function.
But pressing Home key will surely call onStop() of your activity and hence you can stop your music service in onStop(). Hope this helps.
When you press the home button, what does it do by default?
It brings the home screen activity to the foreground.
I want to keep what it does by default, but make sure it ends my music as well.
Stop the music in onPause() or onStop() of your foreground activity, as these will be called when it loses the foreground to the home screen activity.
If you are talking in coding sense -
The home button brings the default launcher to the foreground.
Call onPause() or onStop with super.onPause() or super.onStop() inside of the method.
If you are talking in literal terms with nothing to do with code then..
The home button launches the default launcher activity, this can be cleared if you installed the launcher on some devices by going settings > applications > manage find the application and then go clear defaults
When the music stops is decided by the developers code, you cant change how it works sorry.
I am really confused. I have read that the back button
calls onDestroy()
can close up your currently-running activity
calls onPause()
I think onPause() should be right. But this is an side effect, because the Activity gets into the background. I found nothing in the docs. But maybe I have overlooked something.
Can someone please explain to me what the back button is supposed to do programmatically? Some references would also be nice. :-)
I have read that the back button calls onDestroy(), can close up your currently-running activity, calls onPause()
All three are correct.
I found nothing in the docs.
Quoting the Android documentation:
When the user presses the BACK key, the current activity is popped from the top of the stack (the activity is destroyed) and the previous activity resumes (the previous state of its UI is restored).
To elaborate, if there is nothing else that will consume the BACK button press (e.g., an open options menu), your Activity will be called with onBackPressed(). The default implementation of this calls finish(). This will take your activity from the running to the destroyed states, calling onPause(), onStop(), and onDestroy() in sequence, as shown in the event flow diagram:
Just to add, browser application overrides onBackPressed() to go back to previously opened tabs (if available) and it not, closes the application.
Can anyone point me out or explain what is the difference between android Home key and Back key and their respective behavior related to an android app/activity.
Thank you.
Back Key :
If you press Back Key, onPause(), onStop() and onDestroy() callbacks will called.
Activity will created again by system calls onCreate() callback, then onStart() and onResume() callbacks will be followed.
Home Key :
If you press Home Key, onPause() and onStop() callbacks will called.
Here Activity will restart by system calls onRestart() callback, then onStart() and onResume() callbacks will be followed.
In addition to #Fosco's comments, using back will usually cause an app to exit, where home will leave it running. This is dependent on the application, but the general pattern is to exit the app when using back on the last activity.
Back key destroys the current Activity, home key doesn't. In the Activity lyfecycle, pressing back calls all the way to current activity's onDestroy() method. On the other hand, pressing home pauses the Activity, which stays alive in background.
The home key takes you to the home screen, the back key takes you back to the previous activity (or home if there's no activity to go back to.)
If you are at the home screen and launch Messaging, then hit back, it's the same as hitting the home key.
If you're in Email and get an alert for a text message, and you choose the notification which takes you to Messaging, then hit Back, you'll go back to Email.
edit: as mentioned by Tim Coker, when the back button takes you to the home screen, it usually terminates the activity. I think this is based on the app, whether it terminates or stays resident.