Joint a is class used to connect two Mobile objects together. The Joint class itself is actually never instantiated--instead, one of the following joint subclasses should be used.

• PrismaticJoint for linear sliding joints between links

• RevoluteJoint for rotational joints between links

• FixedJoint for static joints between links

• BallJoint for ball joints between links

• UniversalJoint for ball joints between links

Although the class itself is never instantiated, the class methods described below are often used with the object's subclasses.

The joints supported in breve can be 1, 2 or 3 degrees of freedom (DOF), meaning that they allow motion in 1, 2 or 3 independent directions.