I'm trying out Android's new Navigation Editor for the first time and I'm not sure if this is a missing feature, intentional omission, or if I'm missing something. I have two fragments and I want the first fragment to be able to navigate to the second one, but I want the activity to finish if back is pressed from either fragment.
With my current setup, I can navigate from mainFragment to newFragment. If I press back from the mainFragment, the activity finishes. The only piece I can't figure out is how to finish the activity when back is pressed from newFragment. I've tried every combination of Pop Behavior settings, but haven't achieved what I'm looking for.
Just set clearTask to "true" on your action.
But your use case is going against the concept of the navigation.
https://developer.android.com/topic/libraries/architecture/navigation/navigation-principles#the_app_should_have_a_fixed_starting_destination
Apps have a fixed destination which is the screen the user sees when they launch your app from the launcher. This destination should also be the last screen the user sees when they return to the launcher after pressing the back button.
See the screenshot and look for Pop Behavior. This option can be used to finish activity.
Please note: Finish activity = pop the Activity off the stack.
Select the action from the Activity to be finished, in navigation graph.
Look for drop down for Pop To.
Select the fragment(i.e. the navHostFragment of the activity to be finished).
Check Inclusive option. (i.e. From current destination point- in ur case, it's an action - to and including this fragment - in ur case navHostFragment of Activity- in the stack will be popped off the stack. And that's what we need!).
Related
I am using the UI Navigation Graph. I have fragment A and B. My application starts on Fragment B to show some information. Then the user can press back and end up in A. Then from A the user usually picks something and ends up in B.
Normally I can pop B from the stack and show A. However, when the app just launches there is no A in the back stack. I guess I could add A to the backstack manually but I wonder if the Navigation UI Graph has something that lets me do this.
I cannot change the order of my application fragments. That means that I still need to show B first.
As per the Principles of Navigation, the start destination of your app should always be the last screen the user sees before they exit your app. That means that your Fragment A should be the start destination of your graph.
As per the Conditional Navigation documentation, if you have important information that the user should see (such as a first time user experience), you should have your Fragment A navigate to your Fragment B. This ensures that when you're on Fragment B, Fragment A is on the back stack already.
I am having an issue creating a back stack with the new android navigation component. I have a main graph with a splash fragment, a loginregister root fragment that has it's own graph, an onboard step 1 fragment with corresponding step 1 graph, step2 fragment with step 2 graph, and a home fragment. When the user logs in, they can go to either step1, step2, or the home. If they go to step2, I want them to be able to hit back and end up at step1, and even better, the last fragment of the step1 graph. I've tried setting global actions and setting popTo, but I often get an error saying that it's ignoring the popTo because step1 isn't part of the back stack. Having a button on the screen to go back so I can call navigate with global action works, but when using the hard back button it will go from step2 to login/register.
Even just a simple case of one graph, fragments A, B, C, D. The user can enter the app at any fragment. If I just try to navigate to fragment C with the BtoC action, then there is an error of this action is unknown to this controller. Currently I have to essentially make a couple navigate calls, one after another.
In on of the navigation training docs it says "And in both cases, you should make the Back button more predictable by inserting into the task's back stack the complete upward navigation path to the app's topmost screen. " But I can't find anywhere that really shows how to do this with the NavController and single activity apps.
Any insight would be appreciated.
I am calling Activity2 from Activity1 through intent and on pressing back button I want my activity2 not to get destroyed and go back to Activity1 and again from activity1 want to start activity2.
I have tried to override the back button but then by using moveTaskToBack(true)
is taking me back to my phones home screen but i want to come back to previous activity.
Activities (and Fragments) are designed to destroy when onBackPressed is called. Since the user has no intention to proceed interaction with the screen anymore.
I think the best approach of your navigation should be use of Fragments with manually handled navigation. When Activity starts initialize both Fragments. When you'll need to open second screen, just replace current fragment with Fragment2. When onBackPressed is called - replace Fragment2 with Fragment1. In this case both fragments are always available to be shown.
One thing to be aware of - state saving, since the system can destroy your app in the background anyway. In this case, save state manually when Activity is being destroyed.
On my app I am using a Main Activity, which has a Navigation Drawer, and as the user go to an options from the drawer, it will change the fragment beging displayed accordingly to the option selected.
If the user hit's "Back button" several times, it will go back to a point in which it will reach my Main Activity, which is a blank and empty layout.
When I reach this point (my main activit, empty), I would like to exit the app, or, open the Navigation Drawer.
The problem is, I don't know any event that shows me that I am back to the Main Activity. I checked the onResume, but it's never called, which makes sense, since the main activity has never been stopped.
I thought perhaps there would be an event from the fragment manager that would be called on the Main Activity when a fragment was detached, and from there I could check if there was no fragment at all attached?
When you push your first fragment, add a tag to it. Something like
transaction.replace( R.id.rootContainer, firstFragment, "rootFragment");
Whenever user presses back button, you can get your rootFragment from FragmentManager
FirstFragment myFragment = (FirstFragment) getSupportFragmentManager().findFragmentByTag("rootFragment");
And check if this fragment is visible or not, by myFragment.isVisible(), if not, then keep popping the stack, if it is visible, it means user is on the first fragment. Now you can either quit the app, or show your menu drawer.
Good night good sir. Thank you for your tip.
I used a different approach, based on your repply, that gave me quite a few insights.
On main activity, I Overrided the onKeyDown and check if it was pressed the Back Button. If yes, then I check the size of my Back Stack.
Uppon that, I decide if I want to finish my application.
Also, thanks for the tip of "labeling" the fragments on the back stack, didn't know I could do that.
Suppose I have 5 drawer items in Activity B. If I select 2, then 3, then 1, What's the proper UX when I press back 1 time? Go back to fragment 3, or go back to Activity A? I see SO posts where people add to the fragment backstack, so it looks like the proper UX is going back to fragment 3. But what if I kept clicking different nav drawer items? It would take a long time for me to return to Activity A.
Try building out the solutions and testing the solutions on a friend. I would also try a solution where a user has a "home button" to return to Activity A. The back button could be set to returning to the last fragment.
If the user is losing any information while navigating back to Activity A and skipping the last fragments then I would consider that poor UX.
I see the overall trend is not adding the fragments to the backstack but going to the previous activity or exiting the app. The responses here have been helpful; thank you.