I have an Android app with multiple activities. The main activity communicates over a network and can launch or dismiss various other activities depending on commands it receives over the network. When an Activity is dismissed I don't want to finish() it, just move it down the stack so it's no longer the top activity. What I really need is a FLAG_ACTIVITY_REORDER_TO_BOTTOM but there is no such thing.
There's an intent flag called FLAG_ACTIVITY_PREVIOUS_IS_TOP and the name implies something like that but I don't understand the description:
"If set and this intent is being used to launch a new activity from an
existing one, the current activity will not be counted as the top
activity for deciding whether the new intent should be delivered to
the top instead of starting a new one. The previous activity will be
used as the top, with the assumption being that the current activity
will finish itself immediately"
Could someone please decode that for me, and if it's not what I want IS there some way to tell an activity to submerge itself below the previous one?
This isn't possible. The activities are stacked and you cant put one back under the other. It sounds like you may want to create a class that extends Android’s android.app.Application.
I found this tutorial online and it looks good. Good luck.
Extending Android's android.app.Application tutorial
You cannot move an activity below a certain activity into the android back Stack. The only way to move a activity in back stack is to open another activity on top of it. You can move an activity on top by creating a single instance of activity using FLAG 'singleTop' in this way your activity will be moved to the top of another activity and only a single instance of activity will be there in stack.
More information about activity back stack and Flags is available here.
Go through this information and all your doubts will get cleared about back stack.
Related
What are Some application examples, or use-cases where (singleInstance, singleTask, singleTop) serves a necessary purpose. i.e. why would one favor one launchMode over the other? so far my experience with them is strictly notes, so it would be helpful to understand where they're used. thank you!
I understand it is known that it means you cannot launch multiple instances of an activity.
In my example, I use singleInstance in my main launcher Activity, because it has Fragments, and it is being launched by notification intent.
If Activity was sent to background after user touched "home" button, I don't want it to be launched from background via notification intent, because it will show the last seen fragment. If I set singleInstance, it will always launch new instance of activity, and show the main fragment.
In my case I can't use singleTask because it holds other activities from my app in the stack, but puts the main activity on top. I don't need that history in the stack.
singleTop launches new instance on an activity only if it is not in top of the stack. if it is on top, it launches from background, that's what I don't need in my app.
Hope I was clear :)
As Android newbie I started to wonder about the Activity lifecycle. I'm having an Activity that loads a list of Persons and displays them. Upon the click of a Person I want to open another Activity showing the details of that Person. I'm currently doing this by creating an Intent on the "PersonDetailActivity" which I then start. So far so good. On the PersonDetail page I would like to have a menu action to go back to the Person list. I again applied the same technique, meaning an Intent that brings me back to the PersonListActivity.
Now I started to wonder what returning to the PersonListActivity means. Will a new instance get created and will I have to reload the persons that it displays in the list? Can you come back to the same instance, avoiding having to reload the list again? Do you then have to pass a pointer to yourself via the intent to the other Activity?
So when will and Activity be re-instantiated and when will it not. Any hints or suggestions are more than welcome. Maybe there are some patterns to be applied for these back and forth menu actions that I'm not yet aware of.
Thanks,
Vincent
Yes,,. Call finish() in second Activity instead of starting new Activity..
There is basically something called Activity stack which stores all Activities in the order they were started.. so if start new Actvity , that sits on top of the stack and preveous one gets below it.. when you call finish the Activity is poped out..
if you don't want to call finish() correct waht ever you were doing then add flag ACTIVITY_CLEAR_TOP in manifest for the 1st Activity..
Basically if you just call the finish() method on your PersonDetailActivity
PersonDetailActivity.this.finish();
it will activate the onResume() method from the Activity that is on the top of the finished one, which here would be your PersonsActivity. You can specify in your onResume() method what you want to perform when turning back there.
I am trying to close a whole stack of activities using the way described here:
How to kill an application with all its activities?
Namely, each activity starts the other one with startActivityForResult, and in onActivityResult calls finish() to close itself together with the activity it opened.
The problem is that the activities in the task still seem to repaint themselves at least once before they close, and this doesn't look good. After closing the topmost activity one sees all previously opened activities like in a very fast slideshow.
How can one avoid this graphical issue?
EDIT: I need that if the user presses HOME button and then presses the app's icon in launcher, he returns to the current state of the stack, not to the very first activity again. So, from what I understand, with such a requirement I can't finish() activities before starting next ones.
That's native behaviour, intended to aid in user Experience. When an Activity is started with startActivityForResult and then finishes, it will (on devices that allow fancy animations) automatically slide away. That helps people not get surprised by the screen suddenly changing.
You could try starting the Activities without startActivityForResult and handling the passing of data to and from Activities manually, then handle how/when Activities finish() and which Activity they pass back to. You might find you implement something where Activities actually pass forward to the appropriate Activity all the time, rather than back to an Activity on the stack.
Intent intent = new Intent();
intent.setClass(getApplicationContext(),
PhoneListCheckboxAES.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
finish();
If u give like this when u are starting the next activity then the graphical problems won't occur
In an app I have very reused Activity, that shows a list of stuff happening on a specific day. The day is specified using Intent Extras.
My problem is, that if the user starts at day=1, then chooses day=2 and then day=1, from the menu, then I would like the back button to go to day=2 and then home. That is, I want to do REORDER_TO_FRONT, but not just based on the name of the activity, but also its extras.
There doesn't seam to be any intent flags suitable for this purpose. I've considered implementing my own 'sub activity stack' using onNewIntent, but it probably wouldn't work very well.
Have you tackled similar problems in your apps? Is there perhaps a way to programmatically access the activity stack, and choose which one is suitable to return to?
Manage your own Activity stack! If I'm not mistaken, you use the same Activity to display each day. Make it single top (FLAG_ACTIVITY_SINGLE_TOP). In the launching intent, pass on the current stack, in your example "121".
Respond to the back button event by launching your Activity with a smaller stack: "12" - or if stack is already "", then just let the Activity handle Back event. Then as you mentioned, use the onNewIntent function to update your Activity.
My Application have 20 activities. Here i want to implement the how to exit from the application when you click on the button(like Logout). it means if you click on the menu button any where of our application then it shows the one button. if click on that then directly comes out from the application. how to implement it.
thanks
Well naresh you can do something like that
first finish the activity from which you are closing application this.finish(); secondly and most impotantly always set a flag i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
this clear top when you switch from one activity to another activity and as you know every activity is kept in stack to so this flag remove old activity from top and push new activity in top so around your whole application only one activity is kept in stack
and if this does not work put the whole application in background by avtivityname.moveTaskToBack(); this will move your whole app in back ground but only one drawback when you start your activity it will show your that activity from which you have moved back
System.exit(0);
should work, don't forget Java common functions work on android, there isn't only the android library!
As for the button being in the menu in every activity, you could create a class derived from Activity which creates and handles the menu properly, and make every other activity inherit that derived activity.
First finish the activity from which you are closing application: this.finish();. Secondly and most impotantly always set a flag i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); This clears top when you switch from one activity to another activity. As you know every activity is kept in a stack to so this flag removes old activity from the top and pushes new activity to the top so around your whole application only one activity is kept in the stack.
If this does not work, put the whole application in background with avtivityname.moveTaskToBack();. This will move your whole app to the background. One drawback: when you start your activity it will show your that activity from which you have moved back.