ActionBar tab badge

badge_background.xml

<?xml version="1.0" encoding="utf-8"?>
    
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval" >
    <solid android:color="@color/badge_background" />
</shape>

MainActivity.java

actionBar.addTab(actionBar.newTab()
    .setCustomView(TabUtils.renderTabView(NotificationsActivity.this, R.string.tab_invitations, R.drawable.tab_orange, numberOfNotifications))
    .setTabListener(tabListener));

tab_badge.xml

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/tab_text"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"
        android:textAppearance="@style/Widget.AppCompat.Light.ActionBar.TabText"/>
    
    <TextView
        android:id="@+id/tab_badge"
        android:layout_width="@dimen/badgeSizeHome"
        android:layout_height="@dimen/badgeSizeHome"
        android:background="@drawable/badge_background"
        android:layout_marginRight="4dp"
        android:layout_marginTop="4dp"
        android:layout_gravity="top|right"
        android:gravity="center"
        android:textColor="@color/white"
        android:textSize="8dp"/>

</FrameLayout>

tab_orange.xml

<?xml version="1.0" encoding="utf-8"?>

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_focused="false" android:state_selected="false" android:state_pressed="false" android:drawable="@android:color/transparent"/>
    <item android:state_focused="false" android:state_selected="true" android:state_pressed="false" android:drawable="@drawable/tab_orange_background"/>
    <item android:state_pressed="true" android:drawable="@drawable/tab_orange_background_pressed"/>
    <item android:state_selected="true" android:drawable="@drawable/tab_orange_background_pressed"/>
</selector>

TabUtils.java

public static View renderTabView(Context context, int titleResource, int backgroundResource, int badgeNumber) {
    FrameLayout view = (FrameLayout) LayoutInflater.from(context).inflate(R.layout.tab_badge, null);
    // We need to manually set the LayoutParams here because we don't have a view root
    view.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
    ((TextView) view.findViewById(R.id.tab_text)).setText(titleResource);
    view.findViewById(R.id.tab_text).setBackgroundResource(backgroundResource);
    updateTabBadge((TextView) view.findViewById(R.id.tab_badge), badgeNumber);
    return view;
}

public static void updateTabBadge(ActionBar.Tab tab, int badgeNumber) {
    updateTabBadge((TextView) tab.getCustomView().findViewById(R.id.tab_badge), badgeNumber);
}

private static void updateTabBadge(TextView view, int badgeNumber) {
    if (badgeNumber > 0) {
        view.setVisibility(View.VISIBLE);
        view.setText(Integer.toString(badgeNumber));
    }
    else {
        view.setVisibility(View.GONE);
    }
}