BodyTrack is a project mainly written in Java, it's free.
Android application for the Bodytrack project
The BodyTrack Android application
This application is part of the BodyTrack project (bodytrack.org), which aims to provide the layperson a means to track variables that correspond to her health via various sensor apparati.
This application tracks the data an Android phone's built-in sensors are well-suited to track: -barcodes of food products -photos of meals -locations