This is just a brief and rough introduction for how to use SNAP API in your own Java application. It should be extended in the future.
Include SNAP dependencies
If you use maven to setup your project you can add the dependencies to SNAP in your pom.xml file. Which maven dependencies are available are best viewed by checking out the SNAP project from senbox-org on GitHub. You can also build the project by building the projects following the How to build SNAP from sources guide.
Example usage of SNAP API
The GitHub repository SNAP Examples provides useful examples. Especially the snap-engine-examples sub-project.