Description
I have a Fragment which has a ViewPager and BottomAppBar. ViewPager is showing 3 fragments, each fragment has it's own FloatingActionButton (as I am using Navigation Component, in my case each fragment is a container of navigation graph).
The Problem
Each time the user is swiping the ViewPager I want to show the fragment and also I want to attach the FloatingActionButton to the BottomAppBar. The problem is that Fragments does not know anything about BottomAppBar as they are in separate modules. What is the best way to do this?
This answer is in 2 parts and there are a number of ways of doing it.
First you need to know when each Fragment is shown to then trigger the Fab to change.
This can be done via 2 method, either use the changes in the Fragment's lifecycle to trigger this change or with a PageChangeListener.
With the current version of Viewpager you can use BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT https://developer.android.com/reference/androidx/fragment/app/FragmentStatePagerAdapter#FragmentStatePagerAdapter(androidx.fragment.app.FragmentManager,%20int)
The onResume method of the Fragment is called when it becomes the primary item (the one shown on screen), this can then be used to trigger the Fab change.
The alternate is to add a PageChangeListener and onPageSelected(int) method https://developer.android.com/reference/androidx/viewpager/widget/ViewPager#addOnPageChangeListener(androidx.viewpager.widget.ViewPager.OnPageChangeListener)
The second part, depending which option chosen and the structure of the project you will probably need to communicate that change between components/fragments.
This can be done a number of ways, most common are interfaces or shared viewmodel.
More details of inter Fragment(component) at https://androidwave.com/passing-data-between-fragments/
e.g.
The activity or possibly the BottomAppBar implements an interface the each Fragment can call to say it is the primary Fragment
Or the BottomAppBar observes the shared viewmodel value that defines which Fragment in on screen and each Fragment updates the share viewmodel value with it's number when it is the primary Fragment,
Related
I have a very simple app that consists of three Fragments and a Bottom Navigation bar, created by using "New Project -> Bottom Navigation Activity" in Android Studio. The first Fragment holds a button, which should take me to the second Fragment, like if the middle button of the Bottom Navigation bar was clicked.
Is there a "standard" way to do this?
I have tried:
using launch(...) of the Navigation component, which seems to launch the Fragment with its own back stack and breaks the bottom navigation.
using setSelectedItemId(...) in different ways, which either results in an exception or breaks bottom navigation in different ways.
In this post, someone asks the exact same question, but it is marked as a duplicate. I fail to find the answer, especially concerning Navigation component.
Clicking the Button should have the same effect as if the user taps the corresponding item in the bottom navigation. So you need to call setSelectedItemId() on the BottomNavigationView. This can only be done in the Activity displaying the BottomNavigationView.
One option is to introduce a shared ViewModel with
a LiveData to be observed by the Activity
a function onButtonClicked() to be called by the OnClickListener of your Button which will update the LiveData
Once the LiveData observer fires, your Activity can call
binding.navView.selectedItemId = R.id.navigation_dashboard
Please note that for passing information about events like this one should choose some data type which can be invalidated after use. See for example LiveData with SnackBar, Navigation and other events (the SingleLiveEvent case)
Paste this code from where you want to go to the second fragment
Fragment fragment = new DashboardFragment();
FragmentManager fm = getActivity().getSupportFragmentManager();
fm.beginTransaction().replace(R.id.frame_layout, fragment).commit();
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i'm quite new to drawer material and i have trouble understanding some things:
I need to create an Activity with a Fragment on it. Different selections on the Drawer must replace the current Fragment with another one, but is the Drawer something in the fragment or it is one for the activity itself. More specifically is the Drawer living in the Fragment and if not is it possible to create it in the Fragment. I am asking this cause i see that when initiating the Drawer you need to fill parent activity. Also when i tried to use the Navigation Drawer template in Android Studio i didn't had the Use a Fragment checkbox.
There are many ways to achieve what you want. But I think the simplest way is:
1) DrawerLayout view should reside in the activity (probably as the base layout).
2) When you click on an item in the draw 2 things happen:
The fragment is replaced (you have one layout to contain the fragment and you just replace the fragment in it).
The items inside the drawer update (if you are making a list you would simply set the data and call notifyDataSetChanged().
Don't forget to save your state so it can recover in case the Activity is recreated.
I am currently using a ViewPager with a TabLayout, the ViewPager as of now consists of three separate fragments.
I would like to be able to switch to a fourth fragment using a button on one of the already present fragments.
However, I do not want the fourth fragment to be accessible through the usual ways (aka scrolling) without using the button to reach the fourth fragment. Similarly, I would like scrolling to be disabled when I am currently displaying my fourth fragment.
What would be the best way to do so?
The current hack that I can think of would be to create a hidden fragment within my main layout. I can then display it when the button is pressed while hiding the ViewPager at the same time.
Are there any better ways to do this?
Include your ViewPager in fragment and onClick make replace for the next fragment, and you can return to ViewPager`s fragment onBackPress.
I am writing an android app that will have a number of different screens that I would like to swipe between, each screen will be a full page except for action bar header. On each screen there is the ability to open up another screen which will also be multiple screens that I would like swipeable. What is the best way to handle this. Do I have one fragment manager that holds all the screens and handle the onPageScrollStateChanged to only allow swipes between the current accessable screens or would I be best off nesting the fragments. I hope the above makes sense.
Thanks in advance
Sounds like you want to use a ViewPager to to swipe between views (Fragment extends View)
You could either:
In a single activity use a FragmentManager that switches between the parent and child Fragments, each with their own ViewPager and nested Fragments
Start a new activity to hold each ViewPager
Both are valid, if the Fragments need to communicate with each other or the Activity option one might suit the project needs better.
For the swiping between views you indeed need a ViewPager
For the nested fragments I would use a wrapper. I struggled a lot with fragments and found that this is the best way. A wrapper is very simple. This is just a fragment that holds other fragments. In the onCreate() of this fragment you get the childFragmentManager and add the fragment you originionally wanted to add. If you want to go to a new fragment you simply get the childFragmentManager again and replace the current item. This way you have nested fragment. You can add this to the backstack in order to get back navigation, but you need to override onBackPressed() inside your activity and call the method popBackStack() from the fragmentManager in order to get the first fragment back.
If you have any questions, comment below.
In my application I am making use of navigation drawer which is in the MainActivity and this navigation drawer has say 5 fragments. I am not maintaining any backstack of these fragments.
Now, the first fragment has one button which when clicked pushes a fragment (which I call an inner fragment). Here, I am maintaining a backstack because I want to get back to the first fragment from the inner fragment.
Now, I have a requirement in which I want to navigate from an activityA to the inner fragment.
Is this possible?
One way that I have thought of is to have the push code inside the first fragments create method (and make this conditional).
But I don't think its an appropriate way. Any suggestions would be helpful.