Develop Reference

Switch between multiple views in Android Studio design

I have an activity that presents a list and some icons. My activity design contains a ConstraintLayout at the top level with the list and the icons as children.
Now there can be a situation where we don't have any data. In that case I would like the activity to show neither list nor icons but instead show an image and some error text.
How would I go about implementing this in a way that I can still edit the layout in the Android Studio design view? In other words, not just add the image and the error text overlapping my normal activity elements and toggle their visibility programmatically. Are there layers or something? Or switchable fragments?
Or like this: How can I group view elements in a way that I can show and hide the whole group in the designer?

Yes, in android are Fragments (Android docs) and You can create two fragments, one for a situation when data is loaded successfully and second if data isn't loaded. You can start with the first fragment and when You get information about failed loading data You can switch fragments to second with information about fail.
But I think You can do this in one ConstraintLayout layout. In Your main layout add on top image as You would like to display it and set visibility parameter android:visibility="gone". Now You see everything and can create UI in design mode. And when You get information about failed with loading data just change image parameter to visible.
To do it programmatically:
ImageView imageView = findViewById(R.id.imageDataFailed);
imageView.setVisibility(View.VISIBLE);
How it looks with two containers:
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- Here is container for success data load. When You failed load data set visibility="gone"-->
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="visible">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Button Success"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
<!-- Here is container for failed data load. If You want to change design just set `visible`-->
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="gone">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Button Failed"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

Fragment Button is found by Activity's findViewById instead of Fragment's inflated view.findViewById

I'm seeing this strange behavior and couldn't find anything similar to this.
So I have a parent Activity and inside is a Fragment, which I'm including in parent via include element and then in parent's onCreate, create Fragment and replace it with this include layout (Tell me if this is a right way? I was using FrameLayout but then switched to include and defined an id to it).
Activity
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.sourcey.materiallogindemo.CustomerDetailActivity"
tools:ignore="MergeRootFrame">
<com.google.android.material.appbar.AppBarLayout>
<com.google.android.material.appbar.MaterialToolbar />
</com.google.android.material.appbar.AppBarLayout>
<include
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintTop_toBottomOf="#id/app_bar"
app:layout_constraintBottom_toTopOf="#id/layout_bottom_bar"
layout="#layout/fragment_customer_detail" />
<androidx.coordinatorlayout.widget.CoordinatorLayout>
<com.google.android.material.bottomappbar.BottomAppBar>
</com.google.android.material.bottomappbar.BottomAppBar>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
Fragment
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context="com.sourcey.materiallogindemo.CustomerDetailFragment"
android:layout_height="match_parent"
android:layout_width="match_parent">
<!-- THIS IS THE CULPRIT -->
<com.google.android.material.button.MaterialButton
android:id="#+id/btn_update_position"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<com.google.android.material.button.MaterialButton />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/sku_list"
app:layoutManager="LinearLayoutManager"
tools:context="com.sourcey.materiallogindemo.CustomerDetailFragment"
tools:listitem="#layout/fragment_s_k_u_item" />
</androidx.constraintlayout.widget.ConstraintLayout>
Fragment is inflated correctly but when I do this inside onCreateView
rootView.btn_update_position.setOnClickListener {
// ... log something
}
and press the Button, it doesn't do anything? Even though most findings were led to this suggestion that I should inflate the view and then set onClickListener.
I also tried doing these
rootView.findViewById<MaterialButton>(R.id.btn_update_position).setOnClickListener {
// ... log something
}
and
val button = rootView.findViewById<MaterialButton>(R.id.btn_update_position)
button.setOnClickListener {
// ... log something
}
but none of them works.
I also tried above approaches in onViewCreated to see if maybe I was not getting the reference but no errors were thrown and no reaction was coming.
Only thing that works is this
activity?.findViewById<MaterialButton>(R.id.btn_update_position)
?.setOnClickListener {
// ... log something
}
I'm trying to understand why this happens? Could this be the issue of using include the Fragment?
NOTE I'm not a pro in android just do hobby work in it so don't know very deeply about it.
EDIT As you can see I have a RecyclerView in Fragment layout, I'm inflating the layout and then setting its adapter items which seems to work fine opposed to button.
rootView.sku_list.adapter = Adapter()

I'm bit confused about what you want to do here
First,<include> doesn't create new view, it just include the xml into the parent xml file so basically it still on activity and you need activity to findViewById
Second, about your question what different between FrameLayout and <include>.
With <include> like i said above, it just add xml file to the parent file, the main usage is for re-use layout (you can include it anywhere) .
With FrameLayout, from official doc : "FrameLayout is designed to block out an area on the screen to display a single item". E.g : you want your layout have a header and footer for all screen, only the middle part change so place a frame layout at middle then load different view for each screen, because that flexibility frame layout usually use for display fragment (you can google how to use frame layout for more details)

SlidingUpPanelLayout problem with visibility

I have a problem with SlidingUpPanelLayout. My view is build like that:
<com.sothree.slidinguppanel.SlidingUpPanelLayout xmlns:sothree="http://schemas.android.com/apk/res-auto"
android:id="#+id/list_sliding_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="top"
sothree:umanoDragView="#+id/dragView"
sothree:umanoOverlay="true"
sothree:umanoPanelHeight="#dimen/filtering_list_closed_height"
sothree:umanoShadowHeight="#dimen/app_bar_elevation">
<androidx.coordinatorlayout.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
// some views
</androidx.coordinatorlayout.widget.CoordinatorLayout>
<FrameLayout
android:id="#+id/list_filtering_fragment_container"
android:name="com.example.test.scenes.list.filtering.FilteringFragment"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</com.sothree.slidinguppanel.SlidingUpPanelLayout>
and it was working until I've added new feature where I have to set list_filtering_fragment_container visibility to GONE. Everything works fine when I switch visibility status but it's not working when I move to another fragment and come back to previous one.
EDIT
It looks like:
Normal state that I want to achieve after set visibility to VISIBLE
State that I have after set visibility to VISIBLE (after changing fragments)
also I can see in layout inspector that location on Screen and height of this element is different for both cases.
I tried to use slidingUpPanel.setPanelState(PanelState.HIDDEN) but it for some reason doesn't work in 100% cases. It look like view goes outside screen and doesn't come back to it's proper position. And question is why it behaves like that?

Android JetPack navigation with multiple stack

I'm using Jetpack Navigation version 1.0.0-alpha04 with bottom navigation. It works but the navigation doesn't happen correctly. For example, if I have tab A and tab B and from tab A I go to Page C and from there I go to tab B and come back to tab A again, I will see root fragment in the tab A and not page C which does not what I expect.
I'm looking for a solution to have a different stack for each tab, so the state of each tab is reserved when I come back to it, Also I don't like to keep all this fragment in the memory since it has a bad effect on performance, Before jetpack navigation, I used this library https://github.com/ncapdevi/FragNav, That does exactly what, Now I'm looking for the same thing with jetpack navigation.

EDIT 2: Though still no first class support (as of writing this), Google has now updated their samples with an example of how they think this should be solved for now: https://github.com/googlesamples/android-architecture-components/tree/master/NavigationAdvancedSample
The major reason is you only use one NavHostFragment to hold the whole back stack of the app.
The solution is that each tab should hold its own back stack.
In your main layout, wrap each tab fragment with a FrameLayout.
Each tab fragment is a NavHostFragment and contains its own navigation graph in order to make each tab fragment having its own back stack.
Add a BottomNavigationView.OnNavigationItemSelectedListener to BottomNavigtionView to handle the visibility of each FrameLayout.
This also takes care of your "...I don't like to keep all this fragment in memory...", because a Navigation with NavHostFragment by default uses fragmentTransaction.replace(), i.e. you will always only have as many fragments as you have NavHostFragments. The rest is just in the back stack of your navigation graph.
Edit: Google is working on a native implementation https://issuetracker.google.com/issues/80029773#comment25
More in detail
Let's say you have a BottomNavigationView with 2 menu choices, Dogs and Cats.
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="#+id/dogMenu"
.../>
<item android:id="#+id/catMenu"
.../>
</menu>
Then you need 2 navigation graphs, say dog_navigation_graph.xml and cat_navigation_graph.xml.
The dog_navigation_graph might look like
<navigation
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/dog_navigation_graph"
app:startDestination="#id/dogMenu">
</navigation>
and the corresponding for cat_navigation_graph.
In your activity_main.xml, add 2 NavHostFragments
<FrameLayout
android:id="#+id/frame_dog"
...>
<fragment
android:id="#+id/dog_navigation_host_fragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:name="androidx.navigation.fragment.NavHostFragment"
app:navGraph="#navigation/dog_navigation_graph"
app:defaultNavHost="true"/>
</FrameLayout>
and underneath add the corresponding for your cat NavHostFragment. On your cat frame layout, set android:visibility="invisible"
Now, in your MainActivity's onCreateView you can
bottom_navigation_view.setOnNavigationItemSelectedListener { item ->
when (item.itemId) {
R.id.dogMenu -> showHostView(host = 0)
R.id.catMenu -> showHostView(host = 1)
}
return#setOnNavigationItemSelectedListener true
}
All that showHostView() is doing is toggling the visibility of your FrameLayouts that are wrapping the NavHostFragments. So make sure to save them in some way, e.g. in onCreateView
val hostViews = arrayListOf<FrameLayout>() // Member variable of MainActivity
hostViews.apply {
add(findViewById(R.id.frame_dog))
add(findViewById(R.id.frame_cat))
}
Now it's easy to toggle which hostViews should be visible and invisible.

The issue has been resolved by the Android team in the latest version 2.4.0-alpha01 multiple backstacks along with bottom navigation support is now possible without any workaround.
https://developer.android.com/jetpack/androidx/releases/navigation

First, I want to make an edit to #Algar's answer. The frame that you want to hide should have android:visibility="gone" instead of invisible. The reason for that in your main layout you would have something like this:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".ui.activity.MainActivity">
<include
android:id="#+id/toolbar"
layout="#layout/toolbar_base" />
<FrameLayout
android:id="#+id/frame_home"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="2"
>
<fragment
android:id="#+id/home_navigation_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:navGraph="#navigation/home_nav" />
</FrameLayout>
<FrameLayout
android:id="#+id/frame_find"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="2"
android:visibility="gone">
<fragment
android:id="#+id/find_navigation_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:navGraph="#navigation/find_nav" />
</FrameLayout>
...
</LinearLayout>
If you wrap your main in a LinearLayout, setting the frame to invisible still make that frame counts, so the BottomNavigation wont appear.
Second, you should create a NavHostFragment instance (ie: curNavHostFragment) to keep track of which NavHostFragment is being visible when a tab in BottomNavigation is clicked. Note: you may want to restore this curNavHostFragment when the activity is destroyed by configuration's changes. This is an example:
#Override
protected void onRestoreInstanceState(#NonNull Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
//if this activity is restored from previous state,
//we will have the ItemId of botnav the has been selected
//so that we can set up nav controller accordingly
switch (bottomNav.getSelectedItemId()) {
case R.id.home_fragment:
curNavHostFragment = homeNavHostFragment;
...
break;
case R.id.find_products_fragment:
curNavHostFragment = findNavHostFragment;
...
break;
}
curNavController = curNavHostFragment.getNavController();

How to create sliding layout like in Google Drive tablet app or Google+ notifications?

I'd like to create an extra-information view similar to that of the Google Drive app (below) on a tablet. When the info button is clicked, this view slides in from the rightcontaining a layout. Another example would be the Google+ app with its notifications slide-out panel:. The SlidingLayer by 6Wunderkinder almost works, but doesn't fade a semi-black background over the views behind the "drawer" and I haven't found another library that does this.
If anybody has any suggestions/solutions please let me know!
Also, I've already looked at this question and none of the answers suggested there are correct either.

For posterity, here's the answer to this question. As Steve Benett's suggestion led me to discover, the correct way to do this is to use two DrawerLayouts, nested within each other like so:
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/drawer_navigation_bar"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.widget.DrawerLayout
android:id="#+id/drawer_sidebar"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
android:id="#+id/fragment_main_content"
android:name="MainContentFragment"
android:layout_height="match_parent"
android:layout_width="match_parent" />
<fragment
android:id="#+id/fragment_sidebar"
android:name="SidebarFragment"
android:layout_width="300dp"
android:layout_height="match_parent"
android:layout_gravity="end" />
</android.support.v4.widget.DrawerLayout>
<fragment
android:id="#+id/fragment_navigation_bar"
android:name="NavigationFragment"
android:layout_height="match_parent"
android:layout_width="300dp"
android:layout_gravity="start" />
</android.support.v4.widget.DrawerLayout>
The innermost DrawerLayout contains the main content of the Activity, whether it be a fragment or some other layout components. fragment_sidebar is the fragment that will be swiped out from the right. Then, on the top-level DrawerLayout you have the fragment_nagivation_bar which houses the left Drawer's ListView or whatever.
Then, in the Activity Java code you have:
mDrawerLayoutLeft= (DrawerLayout) findViewById(R.id.drawer_navigation_bar);
mDrawerLayoutRight = (DrawerLayout) findViewById(R.id.drawer_sidebar);
mDrawerLayoutLeft.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
mDrawerLayoutRight.setDrawerShadow(R.drawable.sidebar_shadow, GravityCompat.END);
An optional addition (but recommended, for consistency of UX) is to hide the other Drawer when one is opened, so your screen doesn't consist solely of Drawers.
I hope this has helped somebody!

This is the DrawerLayout. Have a look at the design guide, which illustrates the behavior well.
If you want to use / customize the "semi-black background" use DrawerLayout.setDrawerShadow() with a drawable. Google hands out a set of drawables here. Download the ActionBar Icon Pack and look for the drawable_shadow.9.png.
If you want that the menu appears from the right, set android:layout_gravity="end" as a property in the second child of the layout.