(1) Unidirectional Aggregation
(2) Unidirectional Composition
(3) Navigability Messages flow in direction of arrow (only)
(4) Associations (relationships between classes).
(5) Aggregation (comprises) relationship relationship.1 Destroying the "whole" does not destroy the parts.
(6 ) Composition (has) relationship.1 The parts are destroyed along with the "whole." Doesn't really exist in Java. In C++
check: http://www.holub.com/goodies/uml/index.html
转自：http://www.javaworld.com.tw/jute/post/view?bid=33&id=166020&sty=1&tpg=1&age=0