I wonder if it is good practice to use nested fragments. Consider, there is Activity. I need to place viewpager at the top of it and list view above viewpager.
It would be better to use two containers one for ViewPager, another for ListView, it is clear.
But the question is is good practice to use antoher fragment as container for two nested. I mean that this fragment will have to layouts for two nested fragments, it will have similiar layout file as activity if there are two fragments without parent one.
So I wonder is it good practice to use one main fragment in each activity which plays container role and store all other components inside this container fragment or it is better just use several fragments inside activity without container fragment.
I would be grateful for any help. Thanks in advance.
The "container" Fragment is not a good idea, simply because it will mean two layers of nested Fragments: the outermost "container" Fragment, inside it the Fragment which holds the ViewPager, and the ViewPager itself which holds a set of Fragments.
It would be better to not have the "container" Fragment at all. Keep the rest same.
Related
Recently delve into fragments and from what I understand to create a fragment you need a java class and the fragments layout. This makes sense. However what I cant seem to wrap my head around is what "container", or layout do I use to store/insert the fragment? In android studio you can use this to insert fragments, or you can use any other of the layouts. But which one is ideal to use?
Also I saw in a reddit post that I shouldn't be using fragments at all and that its preferred to instead use Frame layouts and play around with your views visibility for the desired effects. Is this true?
You're slightly over-complicating the concept of Fragments.
Fragments, like Activities, don't actually need a dedicated fragments layout xml file. If you choose to do so, you can create the entire layout through Java code, not that I will understand why you'll choose to do so.
So for Fragments, you don't need a Java class and a fragment's layout file. The only requirement is the Java class, and the layouts file is just the preferred approach to inflating a layout, similar to how it is for Activities.
As for your question about the container of the fragments, it's really a matter of your app's design.
You can add a Fragment to your Activity or other Fragments, through the FragmentManager in code or through the <fragment> tag in your layout.xml files.
Neither of those are the best way or the preferred way, since it really depends on what your app needs.
Using the <fragment> tag will cause that fragment to always be added whenever the layout is inflated. This is actually VERY bad if your Activity requires dynamically switching Fragments due to your use of things like ViewPagers, Tabs, Drawer Navigation, or etc. However, it's GREAT if there's no need to dynamically switch fragments and for that specific Activity or parent Fragment, this fragment is a fragment that's always loaded.
For example, let's say you designed a flexible AddNew Fragment that's used in a Dialog and an AddNewActivity. Due to reusing the same screen and code, you decide to make this part of your code a fragment so you can insert it inside a DialogFragment or into another Activity. But, for those DialogFragments and Activities, the only Fragment it'll have is the AddNewFragment, so it'll make sense to just insert that fragment into the Dialog layout and Activity layout through the <fragment> tag.
As for the option with Java code, the preferred approach is to use a FrameLayout. But there's no need to play around with any View visibilities!
The common approach is to just use:
<FrameLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
A FrameLayout is used because it's going to be the container of the Fragment. In other words, the Fragment will be stored inside of this layout.
So in Java code, you can simply use this code to replace the Fragment inside the container with your new one:
getSupportFragmentManager().beginTransaction().replace(R.id.container, AddNewFragment.newInstance()).commit();
Optionally, you can use add() instead of replace() if you want the fragment to be placed ontop of another fragment within the FrameLayout container.
So yes, to give a decisive answer to your question, there's no ideal way to add a Fragment to an Activity or another Fragment. Each option has it's benefits and drawbacks, with some working better for certain situations and others working better for others.
In the end, it really depends on what your App needs. If you need your Fragments to be flexible, so you can switch Fragments, then this must be done through Java code, because fragments added through the <fragment> tag can't be removed at runtime. However, if you don't need your Fragment to be replaced and it's definitely always going to be showing the same Fragment, then using the <fragment> tag removes the need to write extra Java code to load the dedicated Fragment.
One thing I really do need to point out is... that reddit page you read about is wrong. The 'preferred' way to use Fragments is not to use FrameLayouts and play around with View visibilities. I actually have no idea why there's even a need to change View visibilities.
You can use the new androidx.fragment.app.FragmentContainerView to get a better performance than FrameLayout.
Here more information.
You could use the Fragment layout, but this isn't very flexible. If you're just showing one Fragment, it should work, but using a FrameLayout and inserting your Fragment into it works better as this allows you to change them on the fly.
You may see a FrameLayout with the id R.id.container or something similar, and what this is used for is the Transaction.
For example, if you want to insert FragmentOne into your layout, you can just do this and it'll put it into R.id.container.
Fragment fragment = new FragmentOne();
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.container, fragment);
transaction.commit();
I need to use part of my activity layout in fragmnent, but I dont know how.
If I use overlaying FrameLayout, I will not have access to the elements behind it. And duplicate part of activity_main_layout in several fragments also is not good idea.
A fragment can't host an activity. Instead you can use nested fragments for this purpose. Fragment Inside Fragment
It looks like i need to use fragments with transparent container in the middle
Right now I've Fragments A with Recyclerview - where I've categories (Image+text).
I want to make Fragment B with Recyclerview - where I've types (Image+text). Same layout, same everything except text/image.
Like this:
https://img.exs.lv/e/z/ezeliitis/frags.png
For instance, I click on Fragments A - first picture (Cars) and it opens Fragments B - in same layout as fragment A, which contains (AUDI, BMW, OPEL ect...). Should I just make copies of fragment A (adapters/viewholders ect.) changing db names/pictures or is there some way to "DRY" the code? Also, isn't it bad having two recyclerviews (performance) ?
Also, movement from one fragment to another is called fragments "..."(what exactly?)
Same layout, same everything except text/image
You must need to replace the RecyclerView adapter, then. No need to start another Fragment, but you're more than welcome to.
isn't it bad having two recyclerviews (performance) ?
Not that I know of. You'd only have one at a time, from what I understand anyways.
movement from one fragment to another is called fragments "..."(what exactly?)
If you do need to switch Fragments, then you want the FragmentTransaction class of the host Activity. That's how you switch. Documentation is pretty good with its example.
https://developer.android.com/training/basics/fragments/communicating.html
In my requirements i need to add multiple nested fragments as am using navigation drawer as a main navigation so am using nested fragments like lets say Fragment a->b->c->d-> like that i have created is that a right way to do with using multiple fragments like would cost anything for application ? As beginner am very confused what to do with is it a bad practice i may be dumb question ! any solution you people are here to help beginner like us thanks in advance!
This is not a bad practice, but mostly we should keep fragments in Activity, instead nesting them which is complex but sometimes, it also depends on design of apps, which we must have to follow either by nested fragments or whatever.
In case of Navigation Drawer, you can be enough by adding fragment to navigation list items click and then start activity on fragment click.
Fragments are very useful.
An Activty can have multiple fragments ,and fragments cannot have fragments inside them.
In Android 4.2 there was support for Nested Fragments Where you can use fragment inside other fragment. But your fragment must be dynamic.
Thanks
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.