The navX-Device Java Library for Android is based upon the Java FTC "RobotCore" Library, and provides an interface to the navX-MXP and navX-Micro "Attitude/Heading Reference System" (AHRS) functionality.
To get started w/the navX-Device Java Library for FTC, please see the Getting Started online documentation.
The AHRS Class is the primary class used to access navX-Device AHRS functionality. To use the AHRS class, instantiate the class using one of the constructors.
For source code which demonstrates using the AHRS class in Java, please see the navX-Device FTC Examples.