Develop Reference

TextView inside fragment with layout_gravity set to center hides behind tabs in tabbed activity

I am trying to implement a scrolling fragment in the Tabbed activity. There's only a single TextView inside the fragment and it works fine as far as layout_gravity is not changed. But as soon as layout_gravity is set to center the content of the TextView hides behind the tabs.
Here's the code:
Fragment
<androidx.core.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".Fragment_1">
<TextView
android:id="#+id/frag1_tv"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="#dimen/text_margin"
android:textSize="#dimen/text_medium"
android:textAlignment="center"
android:textColor="#color/black"
android:text="#string/buddha_vandana_mar" />
</androidx.core.widget.NestedScrollView>
And ViewPager:
<androidx.coordinatorlayout.widget.CoordinatorLayout 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"
tools:context=".PrayerActivity">
<androidx.viewpager.widget.ViewPager
android:id="#+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:liftOnScroll="true"
android:theme="#style/Theme.BuddhaPoojapathMarathi.AppBarOverlay">
<com.google.android.material.tabs.TabLayout
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
app:layout_scrollFlags="scroll|enterAlways"/>
</com.google.android.material.appbar.AppBarLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
Without layout_gravity:center looks like following:
With layout_gravity:center set looks like following:

Add android:fitsSystemWindows="true" in your root layout.
<androidx.core.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".Fragment_1"
android:fitsSystemWindows="true"
>

Android Tabs and CoordinatorLayout, need to add a row of textViews

Android Studio 3.5.1. Working with the Tabbed Activity template. I really don't understand the CoordinatorLayout stuff.
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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"
tools:context=".ChecklistActivity">
<androidx.viewpager.widget.ViewPager
android:id="#+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<com.google.android.material.tabs.TabLayout
android:id="#+id/tabs"
app:tabMode="scrollable"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary" />
</com.google.android.material.appbar.AppBarLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
This works great. Using Tabs with ListView on each tab, etc.
But, at the bottom of the screen, I want to add a row of TextViews that contain different status info. (e.g. Time since start, Counts, etc.) So I put a LinearLayout at the bottom of the XML. And added a few TextViews. It shows in Design View in Studio. But at the TOP. But when I launch the App on my phone, I don't see it anywhere.
So in short, how do I work with this XML (CoordinatorLayout) to add such a 'status bar' to my view at the bottom of the screen?

Use a RelativeLayout as the first child inside the CoordinatorLayout. Have the property android:layout_height="wrap_content" and android:layout_alignParentBottom="true" to the TextViews. The rest, i.e. ViewPager and TabLayout can remain as they are.
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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"
tools:context=".ChecklistActivity">
<!-- You could even use a ScrollView -->
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<com.google.android.material.tabs.TabLayout
android:id="#+id/tabs"
app:tabMode="scrollable"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary" />
</com.google.android.material.appbar.AppBarLayout>
<androidx.viewpager.widget.ViewPager
android:id="#+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="#id/lilayTextViews"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
<LinearLayout
android:id="#+id/lilayTextViews"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:orientation="horizontal">
<!-- TextViews go here -->
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Text 1"/>
</LinearLayout>
</RelativeLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

Collapsing Linear Layout

I'm working on android application just for learning purposes an in the app I have a Relative layout who has another linear layout in it and a RecyclerView. The RecyclerView is there to show a list of friends for the particular user and the Linear layout is to give an option to the user to click on it and to be redirected to another activity where he can add new friends. This is the .xml file.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/addFriendLayout">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/add_new_friend"
android:gravity="center"
android:textSize="24sp"
android:textStyle="bold"
android:layout_margin="16dp"
android:textColor="#color/addNewFriendTextColor"/>
</LinearLayout>
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/friendsRecyclerView"
android:layout_below="#+id/addFriendLayout"/>
</RelativeLayout>
What I want to do?
-When the user scroll up I want that Linear layout to hide behind the toolbar and then when user scroll down to collapse and become visible.
This is one similar case like mine but I didn't understand how to do it.
Stack Overflow link

check this code.. I hope this may help you
<android.support.design.widget.CoordinatorLayout
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"
android:fitsSystemWindows="true">
<android.support.design.widget.AppBarLayout
android:id="#+id/app_bar_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fitsSystemWindows="true">
<android.support.design.widget.CollapsingToolbarLayout
android:id="#+id/collapsing_toolbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_scrollFlags="scroll|exitUntilCollapsed"
android:fitsSystemWindows="true"
app:contentScrim="?attr/colorPrimary"
app:expandedTitleMarginEnd="44dp"
app:expandedTitleMarginStart="10dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#color/colorAccent"
android:orientation="vertical"
android:padding="20dp">
<!--your design here-->
</LinearLayout>
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light"
app:layout_collapseMode="pin" />
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v7.widget.RecyclerView
android:id="#+id/recycler"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical"
app:layout_behavior="#string/appbar_scrolling_view_behavior"/>
</android.support.design.widget.CoordinatorLayout>

ViewPager extends over the bottom of the screen

I'm new to Android development and I'm facing the following issue.
This is the layout of my main activity:
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
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">
<android.support.design.widget.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar_main"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:elevation="4dp"
app:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light"
app:layout_scrollFlags="scroll|enterAlways">
<android.support.design.widget.TabLayout
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:tabIndicatorColor="#color/white"
app:tabTextColor="#color/selected_text"
app:tabSelectedTextColor="#color/white"/>
</android.support.v7.widget.Toolbar>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="#+id/main_pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"/>
</android.support.design.widget.CoordinatorLayout>
For each tab in the ViewPager I have a fragment, and this is the layout of one of them
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#color/colorPrimary"
android:id="#+id/linear_layout"
tools:context=".fragments.Reviews">
<RatingBar
android:id="#+id/review_totalRating"
style="?android:attr/ratingBarStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:numStars="5"
android:stepSize=".5"
android:isIndicator="true"
android:progressTint="#color/golden"
android:layout_gravity="center"
android:paddingTop="10dp"
android:paddingBottom="5dp" />
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:divider="#android:color/transparent"
android:dividerHeight="8dp"
android:paddingLeft="8dp"
android:paddingRight="8dp"
android:id="#+id/listView_reviews" />
</LinearLayout>
Then I populate my ListView with items whose layout is defined in another xml file. My problem is with the ViewPager layout_height: it is now set to match_parent, but the element extends over the bottom of the screen, with the result that the last element of the ListView is covered by the navigation buttons.
This is what I see in the design editor
ViewPager overflow
How can I make the element stop before the navigation buttons?

I faced this issue too. It's because of AppBarLayout behavior in CoordinatorLayout. By default when you create a project from a template it will set up layout with hiding Toolbar. You can run your example and check it - just swipe toolbar up and it will hide and ViewPager will move up and then correctly sticks to the bottom of the screen.
It's not a solution for some cases so you can disable this behavior by removing app:layout_scrollFlags attribute from your Toolbar. After this, the toolbar will become unhideable and the ViewPager will calculate own height correctly.

I solved using a LinearLayout as the only child of the CoordinatorLayout, so everything else becomes a children of the LinearLayout. It seems to me to be just a simple workaround, not a final solution, but now it works. This is now the layout of my main activity:
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
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">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.design.widget.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar_main"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:elevation="4dp"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light"
app:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.design.widget.TabLayout
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:tabIndicatorColor="#color/orange_050"
app:tabSelectedTextColor="#color/orange_050"
app:tabTextColor="#color/orange_050"/>
</android.support.v7.widget.Toolbar>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="#+id/main_pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"/>
</LinearLayout>

Fragment from View Pager hiding behind Tab Bar

I am having an issue with a Tab bar and ViewPager in my android project. What the app does it has an activity which hosts a tab layout and then has 2 fragment which represents each of the tabs.
When the activity is opened it posts to an API to get some data and puts the data into a data adapter for a Recycler View and Card layout in each of the fragments.
The recycler view will contain 3 items but only 2 are being shown as the first is being hidden under the toolbar and/or the tab bar as shown in the screenshot below.
Below is the layout file of my activity
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context="com.BoardiesITSolution.CritiMonApp.AppsActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
<include layout="#layout/toolbar" />
<android.support.design.widget.TabLayout
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabMode="fixed"
app:tabGravity="fill" />
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="#+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<!--app:layout_behaviour="#string/appbar_scrolling_view_behaviour" />-->
</android.support.design.widget.CoordinatorLayout>
Below is the layout of the fragment
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<view
android:id="#+id/recycler_view"
class="android.support.v7.widget.RecyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true" />
</LinearLayout>
Below is the layout for card layout
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:cardview="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="80dp"
android:layout_margin="8dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="80dp"
android:elevation="5dp">
<TextView
android:id="#+id/txtApplicationName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:maxLines="3"
android:padding="8dp"
android:textColor="#222"
android:textSize="15dp"
android:layout_centerInParent="true"/>
</RelativeLayout>
</android.support.v7.widget.CardView>
Below is the screenshot as mentioned above which shows the problem. I've pixelated some of the text but it should you what I mean, there should be 3 items but the first item is hiding underneath the tab bar.

Edit: As suggested below by #smeet and #hardik, adding the scroll behavior app:layout_behavior="#string/appbar_scrolling_view_behavior" should fix the problem while preserving the scroll behavior. Scroll behaviors only work if the view is a direct child of the coordinator layout.
Old Answer
Just Wrap your appbar layout and viewpager in a vertical LinearLayout
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context="com.BoardiesITSolution.CritiMonApp.AppsActivity">
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
//appbar layout
//viewpager
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>
From the docs, CoordinatorLayout is a super-powered FrameLayout. So you can expect the typical "lay views on top of other views" FrameLayout behavior.

Adding :
app:layout_behavior="#string/appbar_scrolling_view_behavior"
in ViewPager resolved issue in my case.

if we will wrap app bar layout with linear layout than toolbar will not hide when you scroll so accepted answer might not help you if you want to hide toolbar when you scroll.
Smeet did it right way but not explained! here is full example with explanation.
add app namspace to CoordinatorLayout
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:app="http://schemas.android.com/apk/res-auto"
......
>
and just add below line in your ViewPager
app:layout_behavior="#string/appbar_scrolling_view_behavior"
complete xml will be as below
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="#style/AppTheme.PopupOverlay" />
<android.support.design.widget.TabLayout
android:id="#+id/tabLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="#+id/viewPager"
android:layout_width="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
android:layout_height="match_parent" />
</android.support.design.widget.CoordinatorLayout>