Tabs are now best implemented by leveraging the ViewPager with a custom "tab indicator" on top. In this guide, we will be using Google's new TabLayout included in the support design library release for Android "M".
Prior to Android "M", the easiest way to setup tabs with Fragments was to use ActionBar Tabs as described in ActionBar Tabs with Fragments guide. However, all methods related to navigation modes in the ActionBar class (such as setNavigationMode(), addTab(), selectTab(), etc.) are now deprecated.
To implement Google Play style sliding tabs, make sure to add the Material Design Components Library. In your root build.gradle, make sure the google() entry is listed:
allprojects {
repositories {
google()
jcenter()
}
}Add this dependency to your app/build.gradle list:
dependencies {
implementation 'com.google.android.material:material:1.1.0'
}Simply add com.google.android.material.tabs.TabLayout, which will be used for rendering the different tab options. The androidx.viewpager.widget.ViewPager component will be used to page between the various fragments we will create.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical">
<com.google.android.material.tabs.TabLayout
android:id="@+id/sliding_tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabMode="fixed" />
<androidx.viewpager.widget.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:background="@android:color/white" />
</LinearLayout>Now that we have the ViewPager and our tabs in our layout, we should start defining the content of each of the tabs. Since each tab is just a fragment being displayed, we need to create and define the Fragment to be shown. You may have one or more fragments in your application depending on your requirements.
In res/layout/fragment_page.xml define the XML layout for the fragment which will be displayed on screen when a particular tab is selected:
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center" />In PageFragment.java define the inflation logic for the fragment of tab content:
// In this case, the fragment displays simple text based on the page
public class PageFragment extends Fragment {
public static final String ARG_PAGE = "ARG_PAGE";
private int mPage;
public static PageFragment newInstance(int page) {
Bundle args = new Bundle();
args.putInt(ARG_PAGE, page);
PageFragment fragment = new PageFragment();
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mPage = getArguments().getInt(ARG_PAGE);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_page, container, false);
TextView textView = (TextView) view;
textView.setText("Fragment #" + mPage);
return view;
}
}The next thing to do is to implement the adapter for your ViewPager which controls the order of the tabs, the titles and their associated content. The most important methods to implement here are getPageTitle(int position) which is used to get the title for each tab and getItem(int position) which determines the fragment for each tab.
public class SampleFragmentPagerAdapter extends FragmentPagerAdapter {
final int PAGE_COUNT = 3;
private String tabTitles[] = new String[] { "Tab1", "Tab2", "Tab3" };
private Context context;
public SampleFragmentPagerAdapter(FragmentManager fm, Context context) {
super(fm);
this.context = context;
}
@Override
public int getCount() {
return PAGE_COUNT;
}
@Override
public Fragment getItem(int position) {
return PageFragment.newInstance(position + 1);
}
@Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles[position];
}
}Finally, we need to attach our ViewPager to the SampleFragmentPagerAdapter and then configure the sliding tabs with a two step process:
onCreate() method of your activity, find the ViewPager and connect the adapter.ViewPager on the TabLayout to connect the pager with the tabs.public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Get the ViewPager and set it's PagerAdapter so that it can display items
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
viewPager.setAdapter(new SampleFragmentPagerAdapter(getSupportFragmentManager(),
MainActivity.this));
// Give the TabLayout the ViewPager
TabLayout tabLayout = (TabLayout) findViewById(R.id.sliding_tabs);
tabLayout.setupWithViewPager(viewPager);
}
}Heres the output:
There are many attributes you can use to customize the behavior of your TabLayout as shown below:
<com.google.android.material.tabs.TabLayout
android:id="@+id/sliding_tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabMaxWidth="0dp"
app:tabGravity="fill"
app:tabMode="fixed" />The most important properties available are listed below:
| Name | Options | Description |
|---|---|---|
tabBackground |
@drawable/image |
Background applied to the tabs |
tabGravity |
center, fill
|
Gravity of the tabs |
tabIndicatorColor |
@color/blue |
Color of the tab indicator line |
tabIndicatorHeight |
@dimen/tabh |
Height of the tab indicator line |
tabMaxWidth |
@dimen/tabmaxw |
Maximum width of the tab |
tabMode |
fixed, scrollable
|
Small number of fixed tabs or scrolling list |
tabTextColor |
@color/blue |
Color of the text on the tab |
You can see all the properties available here.
Normally, the tab indicator color chosen is the accent color defined for your Material Design theme. We can override this color by defining a custom style in styles.xml and then applying the style to your TabLayout:
<style name="MyCustomTabLayout" parent="Widget.Design.TabLayout">
<item name="tabIndicatorColor">#0000FF</item>
</style>You can then override this style for your TabLayout:
<com.google.android.material.tabs.TabLayout
android:id="@+id/tabs"
style="@style/MyCustomTabLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</com.google.android.material.tabs.TabLayout>There are several other styles that can be configured for the TabLayout:
<style name="MyCustomTabLayout" parent="Widget.Design.TabLayout">
<item name="tabMaxWidth">@dimen/tab_max_width</item>
<item name="tabIndicatorColor">?attr/colorAccent</item>
<item name="tabIndicatorHeight">2dp</item>
<item name="tabPaddingStart">12dp</item>
<item name="tabPaddingEnd">12dp</item>
<item name="tabBackground">?attr/selectableItemBackground</item>
<item name="tabTextAppearance">@style/MyCustomTabTextAppearance</item>
<item name="tabSelectedTextColor">?android:textColorPrimary</item>
</style>
<style name="MyCustomTabTextAppearance" parent="TextAppearance.Design.Tab">
<item name="android:textSize">14sp</item>
<item name="android:textColor">?android:textColorSecondary</item>
<item name="textAllCaps">true</item>
</style>Currently, the TabLayout class does not provide a clean abstraction model that allows for icons in your tab. However, you can manually add the icons after you have setup your TabLayout.
Inside your FragmentPagerAdapter, you can delete the getPageTitle() line or simply return null:
// ...
@Override
public CharSequence getPageTitle(int position) {
return null;
}After you setup your TabLayout, you can use the getTabAt() function to set the icon:
// setup TabLayout first
// configure icons
private int[] imageResId = {
R.drawable.ic_one,
R.drawable.ic_two,
R.drawable.ic_three };
for (int i = 0; i < imageResId.length; i++) {
tabLayout.getTabAt(i).setIcon(imageResId[i]);
}Sliding tabs with images:
We can also apply color tinting to the tabs by following this guide.
Another approach is to use SpannableString to add icons and text to TabLayout:
@Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
Drawable image = context.getResources().getDrawable(imageResId[position]);
image.setBounds(0, 0, image.getIntrinsicWidth(), image.getIntrinsicHeight());
// Replace blank spaces with image icon
SpannableString sb = new SpannableString(" " + tabTitles[position]);
ImageSpan imageSpan = new ImageSpan(image, ImageSpan.ALIGN_BOTTOM);
sb.setSpan(imageSpan, 0, 1, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
return sb;
}By default, the tab created by TabLayout sets the textAllCaps property to be true, which prevents ImageSpans from being rendered. You can override this behavior by changing the tabTextAppearance property.
<style name="MyCustomTabLayout" parent="Widget.Design.TabLayout">
<item name="tabTextAppearance">@style/MyCustomTextAppearance</item>
</style>
<style name="MyCustomTextAppearance" parent="TextAppearance.Design.Tab">
<item name="textAllCaps">false</item>
</style>Note the additional spaces that are added before the tab title while instantiating SpannableString class. The blank spaces are used to place the image icon so that the actual title is displayed completely. Depending on where you want to position your icon, you can specify the range start…end of the span in setSpan() method.
In certain cases, instead of the default tab view we may want to apply a custom XML layout for each tab. To achieve this, iterate over all the TabLayout.Tabs after attaching the sliding tabs to the pager:
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Get the ViewPager and set it's PagerAdapter so that it can display items
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
SampleFragmentPagerAdapter pagerAdapter =
new SampleFragmentPagerAdapter(getSupportFragmentManager(), MainActivity.this);
viewPager.setAdapter(pagerAdapter);
// Give the TabLayout the ViewPager
TabLayout tabLayout = (TabLayout) findViewById(R.id.sliding_tabs);
tabLayout.setupWithViewPager(viewPager);
// Iterate over all tabs and set the custom view
for (int i = 0; i < tabLayout.getTabCount(); i++) {
TabLayout.Tab tab = tabLayout.getTabAt(i);
tab.setCustomView(pagerAdapter.getTabView(i));
}
}
//...
}Next, we add the getTabView(position) method to the SampleFragmentPagerAdapter class:
public class SampleFragmentPagerAdapter extends FragmentPagerAdapter {
private String tabTitles[] = new String[] { "Tab1", "Tab2" };
private int[] imageResId = { R.drawable.ic_one, R.drawable.ic_two };
public View getTabView(int position) {
// Given you have a custom layout in `res/layout/custom_tab.xml` with a TextView and ImageView
View v = LayoutInflater.from(context).inflate(R.layout.custom_tab, null);
TextView tv = (TextView) v.findViewById(R.id.textView);
tv.setText(tabTitles[position]);
ImageView img = (ImageView) v.findViewById(R.id.imgView);
img.setImageResource(imageResId[position]);
return v;
}
}With this you can setup any custom tab content for each page in the adapter.
With the recent updates to the design support library, you can also get the selected tab position by calling getSelectedTabPosition(). If you need to save or restore the selected tab position during screen rotation or other configuration changes, this method is helpful for restoring the original tab position.
First, move your tabLayout and viewPager as member variables of your main activity:
public class MainActivity extends AppCompatActivity {
TabLayout tabLayout;
ViewPager viewPager;Next, we can save and restore the last known tab position by implementing methods on onSaveInstanceState() and onRestoreInstanceState() to persist this data. When the view is recreated, we can use this data and set the current tab to the last selected tab value.
public static String POSITION = "POSITION";
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt(POSITION, tabLayout.getSelectedTabPosition());
}
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
viewPager.setCurrentItem(savedInstanceState.getInt(POSITION));
}