Android coding example to Set fontFamily

Android 4.1 adds several more variants of the Roboto font style for a total of 10 variants, and they're all usable by apps. Your apps now have access to the full set of both light and condensed variants. - http://developer.android.com/about/versions/android-4.1.html

Example:

MainActivity.java

package com.example.androidfront;

import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.EditText;
import android.widget.Spinner;
import android.graphics.Typeface;
import android.os.Bundle;

public class MainActivity extends ActionBarActivity {
 
 String typeFaceName[] = {
  "sans-serif",
  "sans-serif-light",
  "sans-serif-condensed",
  "sans-serif-thin",
  "sans-serif-medium"};

 CheckBox checkBold, checkItalic;
 Spinner selTypeFace;
 EditText editArea;
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  
  editArea = (EditText)findViewById(R.id.editarea);
  
  checkBold = (CheckBox)findViewById(R.id.boldsel);
  checkBold.setOnCheckedChangeListener(new OnCheckedChangeListener(){

   @Override
   public void onCheckedChanged(CompoundButton buttonView,
     boolean isChecked) {
    updateFonts();
   }});
  
  checkItalic = (CheckBox)findViewById(R.id.italicsel);
  checkItalic.setOnCheckedChangeListener(new OnCheckedChangeListener(){

   @Override
   public void onCheckedChanged(CompoundButton buttonView,
     boolean isChecked) {
    updateFonts();
   }});
  
  selTypeFace = (Spinner)findViewById(R.id.typefacesel);
  ArrayAdapter<String> adapter = 
   new ArrayAdapter<String>(this, 
    android.R.layout.simple_spinner_item, typeFaceName);
  adapter.setDropDownViewResource(
    android.R.layout.simple_spinner_dropdown_item);
  selTypeFace.setAdapter(adapter);
  selTypeFace.setOnItemSelectedListener(new OnItemSelectedListener(){

   @Override
   public void onItemSelected(AdapterView<?> parent, View view,
     int position, long id) {
    updateFonts();
   }

   @Override
   public void onNothingSelected(AdapterView<?> parent) {}});

 }
 
 private void updateFonts(){

  int tfSel = selTypeFace.getSelectedItemPosition();
  String selTypeFaceName = typeFaceName[tfSel];
  
  int style;
  
  if(!checkBold.isChecked() && !checkItalic.isChecked()){
   style = Typeface.NORMAL;
  }else if(checkBold.isChecked() && !checkItalic.isChecked()){
   style = Typeface.BOLD;
  }else if(!checkBold.isChecked() && checkItalic.isChecked()){
   style = Typeface.ITALIC;
  }else{
   style = Typeface.BOLD_ITALIC;
  }
  
  Typeface tf = Typeface.create(selTypeFaceName, style);
  editArea.setTypeface(tf);

 }

}

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.androidfront.MainActivity"
    android:orientation="vertical" >
    
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="android-coding.blogspot.com"
        android:textSize="24dp"
        android:textStyle="bold" />
    
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal" >
        
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:orientation="vertical" >
            
            <TextView
                android:fontFamily="sans-serif"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="@string/test"/>
            <TextView
                android:fontFamily="sans-serif-light"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="@string/test"/>
            <TextView
                android:fontFamily="sans-serif-condensed"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="@string/test"/>
            <TextView
                android:fontFamily="sans-serif-thin"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="@string/test"/>
            <TextView
                android:fontFamily="sans-serif-medium"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="@string/test"/>
            
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:orientation="vertical" >
            
            <Spinner
                android:id="@+id/typefacesel"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"/>
            <CheckBox 
                android:id="@+id/boldsel"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="BOLD"/>
            <CheckBox 
                android:id="@+id/italicsel"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="ITALIC"/>
            <EditText
                android:id="@+id/editarea"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:singleLine="false"
                android:gravity="top"
                android:background="#E0E0E0"/>
        </LinearLayout>
        
        
    </LinearLayout>
</LinearLayout>

string resources of "test" is needed, read HERE.