jOOU is filling up the gap with one of Java's most wanted features: The unsigned number types.

Incredibly, there seems no simple implementation available for just the four basic unsigned integer types as wrappers:

UByte, UShort, UInteger, ULong

See also this stack overflow question here: http://stackoverflow.com/questions/8193031/is-there-a-java-library-for-unsigned-number-type-wrappers

So I have implemented these four classes, extending java.lang.Number and implementing java.lang.Comparable<?>. Besides, there is a utility class called org.joou.Unsigned with factory methods allowing for creating unsigned wrappers like this:

import static org.joou.Unsigned.*;

// and then...
UByte    b = ubyte(1);
UShort   s = ushort(1);
UInteger i = uint(1);
ULong    l = ulong(1);

This was created for http://www.jooq.org, to provide better support for MySQL, Postgres, and other databases' unsigned integer data types.