1. A computer-executed method of automatically generating a sequence diagram from Class-Responsibility-Collaborator (CRC) information, the CRC information identifying objects, responsibility information for each object, and collaborator information for each object, and the CRC information corresponding with each activity in an activity diagram, the method comprising: storing, in a storage device, the objects and corresponding class types of the objects according to the CRC information; associating, by a processor, each of the objects with one or more other objects according to the collaborator information of the CRC information; determining, by the processor, messages from each of the objects to associated objects according to the responsibility information; and the processor automatically generating the sequence diagram including the objects and the messages among the objects.