for my final year project I am developing an android app that can capture the image of a leaf and identify what type of tree it came from. I have a nearly completed PC version
You can convert a BufferedImage to a PNG or JPEG, then send it via HTTP to Android which can then convert the PNG or JPEG back to a Bitmap and use it.
When Android needs to send any image, send it as PNG or JPEG via network, and then convert the PNG to BufferedImage and use it in your program.