Link and association in JAVA

• Link and Association are the means for establishing relationship among objects and classes.

• Link and Association often appears as verbs in problem statement.

• Link is physical / conceptual connection among objects most links relate two objects, but some links relate three or more object. It is am instance of association as shown in figure below.

• Association is a description of a group of links with common structure and common semantics as in the class diagram shown in figure below.

• Association are indirectly bidirectional.

• Both the direction of traversal is equally meaningful.

• It is the only name of the association that established the direction.

• Developers often implements association in programming language as a references from one object to another.

• Associations are important, precisely because they break encapsulation.

• Association cannot be private to a class, because they go beyond classes.