Develop Reference

How is TabItem used when placed in the layout XML?

The TabLayout documentation gives an example of nesting TabItem directly inside TabLayout like so:
<android.support.design.widget.TabLayout
android:layout_height="wrap_content"
android:layout_width="match_parent">
<android.support.design.widget.TabItem
android:text="#string/tab_text"/>
<android.support.design.widget.TabItem
android:icon="#drawable/ic_android"/>
</android.support.design.widget.TabLayout>
But it gives no example of how this could be used in practice, and the documentation for TabItem says:
This view is not actually added to TabLayout, it is just a dummy which allows setting of a tab items's text, icon and custom layout.
So what is TabItem for? After extensive Googling, I cannot find a single example of anyone defining TabItems in XML. Is there any way to set up a tabbed activity using TabItem in the resource file as shown above?

This appears to be a relatively recent addition to the design library, apparently added in version 23.2.0, though it's not mentioned in the revision history. It's functionality is pretty basic, and the only attributes it seems to use are the three given in its docs: text, icon, and layout.
From testing, it seems it's basically an XML shortcut for creating a new Tab, and setting its text, icon, and custom View, as one would usually do in code. When it says "This view is not actually added to TabLayout", I believe it's meant to suggest that it's not a View in the regular sense, in that you can't set any kind of standard layout attribute on it, like layout_width or background. It simply serves to cause the TabLayout to create a new Tab for each TabItem, and call setText(), setIcon(), and setCustomView() accordingly.
For example, to add a Tab in code, we would usually do something like this:
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
// Add Tab
TabLayout.Tab tab = tabLayout.newTab();
tab.setCustomView(R.layout.tab);
tab.setText("Tab 1");
tab.setIcon(R.drawable.ic_launcher);
tabLayout.addTab(tab);
Whereas now we can replace everything after the comment above by adding a TabItem in the layout.
<android.support.design.widget.TabLayout
android:id="#+id/tab_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.design.widget.TabItem
android:layout="#layout/tab"
android:text="Tab 1"
android:icon="#drawable/ic_launcher" />
</android.support.design.widget.TabLayout>
Do note that the same requirements for the custom View layout still apply. That is, the TextView for the text must have the system Resource ID #android:id/text1, and the ImageView for the icon must have the ID #android:id/icon. As an example, the R.layout.tab from above:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center_vertical">
<ImageView android:id="#android:id/icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<TextView android:id="#android:id/text1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>

Quick addition to #Mikes very helpful answer:
Android Studio now has a Template on how to use a TabLayout with TabItem setup in an XML layout. Create all needed files with "New > Activity > Tabbed Activity" and choose "Action Bar Tabs(with ViewPager)" as shown in the screenshot:
If you want to adjust the look of the TabItem without a custom view: use white vector assets as tab android:icon and tint them with a selector (providing different colors based on android:state_selected)
The color of the line under the currently selected tab is set as app:tabIndicatorColor on tag TabLayout.
It took me a while to get it to work, so the complete steps turned into such a long answer that I don't want to copy them here. You can find my more detailed answer with full code at:
https://stackoverflow.com/a/49603559/414581

please see com.google.android.material.tabs.TabItem class it accepts icon text from attributes, but seems like you will need to add Tags on runtime.

TabLayout scrollable tabs padding is calculated badly

We have this TabLayout in xml:
<android.support.design.widget.TabLayout
android:id="#+id/sliding_tabs"
app:tabGravity="fill"
app:tabContentStart="#dimen/tab_content_start"
app:tabIndicatorColor="#color/MaterialDividerColor"
app:tabSelectedTextColor="#color/DarkRed"
app:tabTextColor="#color/Black"
android:layout_width="match_parent"
android:layout_height="wrap_content"
The problem is, when displaying on a tablet it looks really weird, all the tabs have the same width and therefor have each wildly different padding:
Surprisingly, on a phone it works as expected, or at least the problem is not visible:
I am using the 23.2.0 support library, which frankly looks full of bugs.

When you have TabLaout which app:tabMode="scrollable", You need to give some value to tabMinWidth, such as app:tabMinWidth="40dp". Otherwise, tab paddings wouldn't work.

Android TabLayout with active tab always at center, just like in Play Newsstand app

In android.support.design.widget.TabLayout, how to make the active tab always appear at the center, just like in Play Newsstand app, as shown below.
The first and last tab should also appear at the center.
I tried using padding on the TabLayout. It is not working. This is the code that I wrote:
<android.support.design.widget.TabLayout
android:id="#+id/tabs"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:tabIndicatorColor="#color/yellow"
app:tabSelectedTextColor="#android:color/white"
app:tabTextColor="#EEE"
app:tabMode="scrollable"
android:gravity="bottom"
android:clipToPadding="false"
android:paddingLeft="90dp"
android:paddingRight="90dp"
/>
In this case, the tabIndicator will also shift 90dp from left. It should remain at the center independent of the padding.

Checkout this solution: https://stackoverflow.com/a/36886331/651770
Could be solved by tabContentStart, but if you want to center both sides of Tablayout, you need to extend this class and set the padding by hand.

Maybe a little late, but you can try using this library :
https://github.com/jpardogo/PagerSlidingTabStrip
This can be done as they said :
Include the following dependency in your build.gradle file.
compile 'com.jpardogo.materialtabstrip:library:1.1.1'
Or add the library as a project. I tried to send a pull request, but looks like the original developer doesn't maintain it anymore.
Include the PagerSlidingTabStrip widget in your layout. This should usually be placed above the ViewPager it represents.
<com.astuetz.PagerSlidingTabStrip
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary" />
In your onCreate method (or onCreateView for a fragment), bind the widget to the ViewPager:
// Initialize the ViewPager and set an adapter
ViewPager pager = (ViewPager) findViewById(R.id.pager);
pager.setAdapter(new TestAdapter(getSupportFragmentManager()));
// Bind the tabs to the ViewPager
PagerSlidingTabStrip tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
tabs.setViewPager(pager);
Hope this help.

How to split the tab view at equal space in the Action Bar in android?

I have added two tab view in the action bar which is looking fine in the portrait mode but is not good in Landscape mode and also in tablet devices. now i need to display two tab view that is to be split up with equal space in landscape mode and large devices like being in portrait mode (you can refer from youtube app which has two tabs that equally split up in both portrait and landscape mode). How can i achieve this? please let me know if know somebody.
output of Portrait Mode.

You should try this in onCreate slidingTabLayout.setDistributeEvenly(true);
I also linked you to a slidenerd video where he would explain more about it

You can use app:tabMode as FIXED as shown below.
<android.support.design.widget.TabLayout
android:id="#+id/pager_header"
android:layout_width="match_parent"
android:background="#color/white"
app:tabTextColor="#color/placeHolder"
android:elevation="1dp"
app:tabMode="fixed"
app:tabTextAppearance="#style/collection_tab"
app:tabSelectedTextColor="#color/blueBG"
android:layout_height="wrap_content"
app:tabGravity="fill" />
<android.support.v4.view.ViewPager
android:id="#+id/vpPager"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</android.support.v4.view.ViewPager>

Swipe part of the page using pager view

I have ViewPager with PagerTabStrip , when swiping from page to another, both the pager and the tab will be moving together. (like google paly)
It's working fine. now all the pages have common data, and one part is going to change when swiping, so i don't want to swipe the whole page, just the area that going to change.
As you can see in the following image just the red area will be effected when swipe pages, the green area will not move.
I've searched a lot, but i can't find anything useful, any help would be appreciated.
viewpager code:
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.view.PagerTabStrip
android:id="#+id/pager_title_strip"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="top"
android:background="#FFFFFF"
android:textColor="#003366"
android:paddingTop="4dp"
android:paddingBottom="4dp"/>
</android.support.v4.view.ViewPager>

Using swipeyTabs is the answer.
The problem when using PagerTabStrip is that the PagerTabStrip will be inside the ViewPager tag see the following code:
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.view.PagerTabStrip
android:id="#+id/pager_title_strip"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="top"
android:background="#FFFFFF"
android:textColor="#003366"
android:paddingTop="4dp"
android:paddingBottom="4dp"/>
</android.support.v4.view.ViewPager>
so you cant separate them form each other.
but when using the SwipeyTabs, each tag will be as a separate part, see the following code:
<net.peterkuterna.android.apps.swipeytabs.SwipeyTabs
android:id="#+id/swipeytabs"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
swipeytabs:bottomBarColor="#ff96aa39"
swipeytabs:bottomBarHeight="2dip"
swipeytabs:tabIndicatorHeight="3dip"
android:background="#ff3b3b3b"/>
<android.support.v4.view.ViewPager
android:id="#+id/viewpager"
android:layout_width="fill_parent"
android:layout_height="0px"
android:layout_weight="1" />
In this case, you can customize your layout as you want by dealing with ViewPager and SwipeyTabs as two parts.
In your case, I guess you can put the SwipeyTabs and ViewPager in red position like in the image, and in the green areas, you have to just adjust them as your needs.
I found these links which may help you. Good luck with that.
Swipey tabs sample
ViewPager meets Swipey Tabs

Disclaimer: I misread your post. Separating the ViewPager from the PagerTabStrip may not work or may need another approach. I'll leave the answer here in case it may help anyway.
You can achieve that by embedding the ViewPager in a separate fragment and placing another independent fragment beneath, which is not controlled by the ViewPager.
Basically, your main activity consists of two fragments: one that contains the ViewPager (which contains more fragments), another one that contains your fixed view.
To do it properly, this needs support for nested fragments, which is only available on Android 4.2 or otherwise in the latest support library (revision 11).
Be aware when instantiating your adapter for the ViewPager, you need to use the FragmentManager returned by getChildFragmentManager().