Android font family matching

fonts.xml

From android 4.1 / 4.2, the following Roboto font families are available:

android:fontFamily="sans-serif"           // roboto regular  
android:fontFamily="sans-serif-light"     // roboto light  
android:fontFamily="sans-serif-condensed" // roboto condensed  
android:fontFamily="sans-serif-thin"      // roboto thin (android 4.2)  
android:fontFamily="sans-serif-medium"    // roboto medium (android 5.0)
in combination with this

android:textStyle="normal|bold|italic" 
12 variants are possible:

Regular
Italic
Bold
Bold-italic
Light
Light-italic
Thin
Thin-italic
Condensed regular
Condensed italic
Condensed bold
Condensed bold-italic

Added in Android Jelly Bean (4.1) - API 16 :

Regular (default):

<item name="android:fontFamily">sans-serif</item>
<item name="android:textStyle">normal</item> 
Italic:

<item name="android:fontFamily">sans-serif</item>
<item name="android:textStyle">italic</item>
Bold:

<item name="android:fontFamily">sans-serif</item>
<item name="android:textStyle">bold</item>
Bold-italic:

<item name="android:fontFamily">sans-serif</item>
<item name="android:textStyle">bold|italic</item>
Light:

<item name="android:fontFamily">sans-serif-light</item>
<item name="android:textStyle">normal</item>
Light-italic:

<item name="android:fontFamily">sans-serif-light</item>
<item name="android:textStyle">italic</item>
Thin :

<item name="android:fontFamily">sans-serif-thin</item>
<item name="android:textStyle">normal</item>
Thin-italic :

<item name="android:fontFamily">sans-serif-thin</item>
<item name="android:textStyle">italic</item>
Condensed regular:

<item name="android:fontFamily">sans-serif-condensed</item>
<item name="android:textStyle">normal</item>
Condensed italic:

<item name="android:fontFamily">sans-serif-condensed</item>
<item name="android:textStyle">italic</item>
Condensed bold:

<item name="android:fontFamily">sans-serif-condensed</item>
<item name="android:textStyle">bold</item>
Condensed bold-italic:

<item name="android:fontFamily">sans-serif-condensed</item>
<item name="android:textStyle">bold|italic</item>
Added in Android Lollipop (v5.0) - API 21 :

Medium:

<item name="android:fontFamily">sans-serif-medium</item>
<item name="android:textStyle">normal</item>
Medium-italic:

<item name="android:fontFamily">sans-serif-medium</item>
<item name="android:textStyle">italic</item>
Black:

<item name="android:fontFamily">sans-serif-black</item>
<item name="android:textStyle">italic</item>
For quick reference, this is how they all look like:

<img src = "http://developer.android.com/design/media/typography_variants@2x.png" />