import ua_parser.Parser;
import ua_parser.Client;

...

  String uaString = "Mozilla/5.0 (iPhone; CPU iPhone OS 5_1_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9B206 Safari/7534.48.3";

  Parser uaParser = new Parser();
  Client c = uaParser.parse(uaString);

  System.out.println(c.userAgent.family); // => "Mobile Safari"
  System.out.println(c.userAgent.major);  // => "5"
  System.out.println(c.userAgent.minor);  // => "1"

  System.out.println(c.os.family);        // => "iOS"
  System.out.println(c.os.major);         // => "5"
  System.out.println(c.os.minor);         // => "1"

  System.out.println(c.device.family);    // => "iPhone"