The relationships between classes

The relationships between classes and classes are:

1. Related relations;

2, the combination of relations;

3, the aggregation relationship;

4, the dependence relationship;

5, inheritance relations;

6, the realization of the relationship;

Among them, the combination relation and the aggregation relation are the special correlation relations.

Association relationship:

A->b a association B is a one-way association, if b->a, it forms two-way association;

Semantics: a knows a B

Code form:

Class a{

B *m_b;

}

The combination relationship and the aggregation relationship are the same in the code form and the correlation, but the semantics are different:

The semantics of combinatorial relationships: A contains a B, A is dead, B is not alive;

The semantics of the aggregation relationship: A contains a B, A is dead, B can live;

Inheritance Relationship:

Semantics: B is a kind of a

Code form:

Class B:a

{

}

In the realization relation, the implementation is often an interface (interface), the code form is the same as the inheritance relation;

Dependency Relationship:

Semantics: A uses a B

Code form:

Class a{

Method (B &b);

}

The relationships between classes