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.

scrollable tabs custom user Interface

I am working on a Scrollable tabs and came to observe a custom scrollable tabe in a mediaplayer app but don't know what is used in this as per my knowledge it is like scrollable tabs.Any hint how to achieve this while changing from one fragment to another .I want to show a gape in the fragment while scrolling as in this app?THIS is what I created
this is what i want a gape between two fragment
I tried to give padding in the view pager but it is not working at all.
my layout content main .xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/pager"
android:background="#drawable/gradient2"
>
<android.support.v4.view.PagerTitleStrip
android:id="#+id/title"
style="#style/viewPagerTitleStrip"
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_gravity="top"
android:paddingTop="4dp"
android:paddingBottom="4dp"
android:background="#drawable/gradient1">
</android.support.v4.view.PagerTitleStrip>
</android.support.v4.view.ViewPager>
I tried both padding and margine in the ViewPager but it is not working

Here is the similar property used try this https://github.com/astuetz/PagerSlidingTabStrip
Since I am using ViewPager, the easiest way to achieve some space is to use the setPageMargin() method of Viewpager, which in my case will be
ViewPager pager = (ViewPager) findViewById(R.id.pager);
pager.setPageMargin(200);
//200 is value in pixel
There is also a method setPageMarginDrawable() sets a drawable that will be used to fill the margin between pages (Android documentation).

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.

Is there any way to have embedded scrollable tabs?

I have a layout in my head that should look like that: http://i.imgur.com/H1nTRvd.png
Only part that will be dynamic is the blue one. I don't know the number of tabs that will be created before I load the activity, hence the number is acquired from server (could be either 5 or 24 for all I know).
The bottom buttons should not move when I swipe and the blue area changed.
Currently I have this implemented w/o tabs list using embedded fragment in my activity and gesture listener. There's no good looking transaction animation between fragments.

#Nick Pakhomov: You can use PagerTabStrip
PagerTabStrip
is intended to be used as a child view of a ViewPager widget in your XML layout. PagerTabStrip is most often used with fragment, which is a convenient way to supply and manage the Lifecycle of each fragment.
So here’s how a ViewPager with a PagerTabStrip in it would look like in the layout file:
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.view.PagerTabStrip
android:id="#+id/pager_tab_strip"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="top"
android:background="#33b5e5"
android:textColor="#fff"
/>
</android.support.v4.view.ViewPager>
Please check this PagerSlidingTabStrip demo . I hope it will helps you .

How to achieve a custom layout with next page title shown half, indicating the user of next page as shown in android

FIRST PAGE
[/IMG]
SECOND PAGE
[/IMG]
I want show my two pages like this, When loading first page the second page title should be shown indicating the user about a second page. How can I achieve this?, I can put two tabs or viewpager with view pager indicator, i want that functionality but actually what I ask here is the view that is marked the image, the next tab to display half of its title indicating the user of next page.
Thanks in advance..

You can directly use ViewPager with PagerTabStrip provided in android support-v4 library.
Download android Support-V4 library here
Then extract the android Support-V4 jar and paste into your project libs Folder.
Right click and Add to build path.
Now use View pager with PagerTabStrip in your Main layout as:
main.xml
<?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" >
<android.support.v4.view.ViewPager
android:id="#+id/viewpage"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#+id/pagetab"
>
<android.support.v4.view.PagerTabStrip
android:id="#+id/pagetab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#333333"
android:background="#ffffff"
android:layout_gravity="top"/>
</android.support.v4.view.ViewPager>
</RelativeLayout>
Now populate the ViewPager using Adapter in Main Class .see here
Now you can Achieve What you want.

I strongly advise you to use a library, instead creating the widget yourself.
That said, this library suit your requirements. It’s really easy to implement it:
PagerSlidingTabStrip tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
tabs.setViewPager(yourViewPager);
You can found a complete implementation here