Add new item count to icon on button – Android

Make your badge a TextView, allowing you to set the numeric value to anything you like by calling setText(). Set the background of the TextView as an XML <shape> drawable, with which you can create a solid or gradient circle with a border. An XML drawable will scale to fit the view as it resizes with more or less text.

res/drawable/badge_circle.xml:

<shape xmlns:android="http://schemas.android.com/apk/res/android"
  android:shape="oval">
  <solid
    android:color="#F00" />
  <stroke
    android:width="2dip"
    android:color="#FFF" />
  <padding
    android:left="5dip"
    android:right="5dip"
    android:top="5dip"
    android:bottom="5dip" />
</shape>

You’ll have to take a look at how the oval/circle scales with large 3-4 digit numbers, though. If this effect is undesirable, try a rounded rectangle approach like below. With small numbers, the rectangle will still look like a circle as the radii converge together.

res/drawable/badge_circle.xml:

<shape xmlns:android="http://schemas.android.com/apk/res/android"
  android:shape="rectangle">
  <corners
    android:radius="10dip"/>
  <solid
    android:color="#F00" />
  <stroke
    android:width="2dip"
    android:color="#FFF" />
  <padding
    android:left="5dip"
    android:right="5dip"
    android:top="5dip"
    android:bottom="5dip" />
</shape>

With the scalable background created, you simply add it to the background of a TextView, like so:

<TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content" 
  android:text="10"
  android:textColor="#FFF"
  android:textSize="16sp"
  android:textStyle="bold"
  android:background="@drawable/badge_circle"/>

Finally, these TextView badges can be placed in your layout on top of the appropriate buttons/tabs. I would probably do this by grouping each button with its badge in a RelativeLayout container, like so:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content">
  <Button
    android:id="@+id/myButton"
    android:layout_width="65dip"
    android:layout_height="65dip"/>
  <TextView
    android:id="@+id/textOne"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@id/myButton"
    android:layout_alignRight="@id/myButton" 
    android:text="10"
    android:textColor="#FFF"
    android:textSize="16sp"
    android:textStyle="bold"
    android:background="@drawable/badge_circle"/>
</RelativeLayout>

Hopefully that’s enough information to at least get you pointed in the right direction!