Java source codes for different purposes. Note that these are not stand-alone programs but purely just Java source code that you have to compile yourself. You can freely use these codes as they are, or modify them for your own purposes.
BitArray - For storing huge boolean arrays, using just one bit per each boolean
ImageToBmp - Turn image or pixels to bmp file bytes
IntegerPrimality - Super fast (pre-calculated) primality test of numbers in Java Integer range
RetroPixel - Turn image to Commodore 64, PC CGA/EGA and Amiga EHB graphics