What is the equivalent operation within an activity to navigating away from the screen. Like when you press the back button, the activity goes out of view. How can this be called from inside an activity so that it closes itself.
What about the Activity.finish() method (quoting) :
Call this when your activity is done
and should be closed.
you can use this.finish() if you want to close current activity.
this.finish()
you can use finishAffinity(); to close all the activity..
finish() method is used to finish the activity and remove it from back stack. You can call it in any method in activity. But make sure you close all the Database connections, all reference variables null to prevent any memory leaks.
You Can use just finish(); everywhere after Activity Start for clear that Activity from Stack.
Related
I launch main activity, change some settings in UI, press back button and then reopen the activity. onCreate() is called again and activity is back to default state. Why is this?
I would expect only onResume() to be called since I have this in Manifest:
android:launchMode="singleInstance"
Try using moveTaskToBack(true); in onBackPressed() to make your current activity hide instead of destroying, so you can reopen it again
#Override
public void onBackPresses(){
moveTaskToBack(true);
}
I launch main activity, change some settings in UI, press back button and then reopen the activity. onCreate() is called again and activity is back to default state. Why is this?
This is expected behavior of activity life cycle. When you press back button then activity get destroyed, it will start from onCreate method.
This is because when you press back, it destroyes the activity.
I think that what you want is to keep the state when you come back to this activity, not really to have one instance of it. So you should save the information you need and then restore them in onCreate.
Single instance only means (if I remember it well) that if you launch multiple activities without finishing them, the ones that have singleInstance will go back to front when you will call startActivity() and will not call onCreate. But this means you can't have this behavior by pressing back.
Maybe you can override onBackPressed and start another activity (the one you should go back to) instead of calling super.onBackPressed(). this should do what you want but if think it will be kind of difficult to manage.
By the way remember that Activities might be killed by the system itself, so you should not rely on the fact that your activity as not been killed
I have 2 activities with fragments inside of them. Whenever I press the back button, the fragment gets destroyed (Used FragmentTransaction's replace method for adding them into the activity) instead of going back to the first activity immediately.
How can I achieve the behavior I want to have?
You can override onBackPressed method in your activity and check if the fragmentManager.getBackStackEntryCount()==0. If yes finish() the activity.
Hope it helps.
My project has 4 activities and users from activity A go to B after that to C and D. I need to create a button in activity D to close program directly because if user has to close all activities ( D ->C -> B -> A-> close) it would be unfriendly.
Register a broadcast receiver in each of the activities, listening for the "close all action", when the button in the last activity is pressed, send that broadcast, so all the activities register will execute their "onReceive" method on the broadcastreceiver, and there all them will be finished as long as they are registered.
This will definitely do the trick, although to be honest is quiet a poor implementation, chances that you are doing something wrong in the navigation are high, maybe fragments or a tab would be better suited for what you are trying, in stead of creating such a stack of activities...
Hope this helps...
Regards!
I think onActivityResult could be the better option.You could finish the activity if required task is being completed otherwise just backtrack on previous activity
You should override onBackPressed() from each Activity and call finish().
Assume the first activity in your application is named ActivityMain. Presumably it will be the oldest one on the stack.
Create an intent to start ActivityMain using the flag FLAG_ACTIVITY_CLEAR_TOP. Set an extra in that intent to indicate this is an application exit, and call startActivity() with that intent. This will clear the stack and get you back to Activity main.
In ActivityMain call getIntent() then check for the exiting application Extra value. If it is set, call finish().
A not so elegant solution:
Instead of calling startActivity, call startActivityForResult, from A to D.
On Activity D, when your button is pressed, set any result (let's say Activity.RESULT_OK) and call finish().
On each Activity (from A to C), override the method onActivityResult to check for the result. If the result is Activity.RESULT_OK, then you set the same result and call finish() again.
If you want, instead of just setting the result, add an Intent with some flag to tell the previous Activities to finish themselves.
Simply do one thing . In your activities add an overriden method onPause
onPause(){
finish();
}
This will close all your activities once you press back from any activity.
I'd like to destroy an Activity when the user clicks on a button (not the back button, a different button). I've decided to just call super.onBackPressed. Is that okay? What's a better way to close the current Activity without closing the whole app?
for closing an Activity you can use finish() , but you have to aware of back stack, if you finish your last activity in the stack so there will be no activity in your stack and you must restart your app .
see more information on : Task and BackStack
The default implementation of super.onBackPressed finishes the activity.
Instead of using super.onBackPressed , Better way to close the current activity will be to call finish() method.
Also, When you press the back button, the onResume method is called.
Use onResume Method and refresh your stuff there.
Also, if it is listView refresh the data -> https://stackoverflow.com/a/12662994/2006412
In Android, from Activity A, if I start new Activity B, Android will automatically save all the state of Activity A. So when I click back or call finish() from Activity B, Activity A will be restored to the state when I start Activity B (for example: position of a ScrollView in Activity A, or the value of ProgressBar). In Activity A I have a ProgressBar showing progress of some task, then if I come back from Activity B, the ProgressBar is restored and keep running.
Now what I want is, from Activity A, I will call finish(). How can I save all the state of Activity A just like Android did (include the ProgressBar as I describe above), so when I start Activity A again, I can restore everything like before calling finish(), and my ProgressBar keep running?
Can I push Activity A to something like stack in Android and then pop it out? Anyone know how to achieve this?
Do not call finish on clicking the back button.
Instead call the method "moveTaskToBack(false)". This will 'minimize' your application.
Next time you open the application the application opens with the previous state.
The whole point of finish() is to say that your Activity is "done and should be closed". If you aren't done, just don't call finish().
When you go from Activity A to Activity B, Android does not kill Activity A. Activity A still lives in the background. It can however be killed at any moment if Android needs the memory.
To save the state of an activity you have to do it manually.
Here's a similar question with a good answer: Saving Android Activity state using Save Instance State
If you want to finish your activity and then start it again just to load some new configurations, You can call activity's recreate() method instead of calling finish(). Calling recreate() will call onSaveInstanceState() and onRestoreInstanceState(), helping you to restore your previous configurations..
You can look at this answer for more detail : How do I restart an Android Activity