JRPiCam is a very simple Java API that uses the ProcessBuilder class to invoke the raspistill software on your Pi. As long as raspistill is configured to work, so will JRPiCam. JRPiCam provides all the relevant functionality of raspistill to a Java app running on the RPi. I whipped up some examples and a javadoc and posted the project along with a .jar library to GitHub, https://github.com/Hopding/JRPiCam.
I hope you guys find it to be helpful. It's simple, but is quicker and easier to use rather than making your own ProcessBuilder based class. Thanks for reading!
It is now possible to read an image directly into a java application, without saving it to memory at all (although the buffered image can be saved after it is in the Java buffer if desired). This allows an image to be accessed far faster than if it is saved to memory and then loaded into the Java app. Images can still be saved and read from memory just like before, if desired. Currently, buffered images are stored in a java.awt.image.BufferedImage object for easy manipulation (e.g. using in JavaCV, or converting with SwingFXUtils for use in a JavaFX application). I am working on a way to get an integer array of the image's RGB values as well, and should be ready to commit it soon.