Three relationships:

1) a combination of the relationship (such as car tires and, computer cpu)

2) dependence (keys and doors)

3) association (students and courses and books)

 

Coupling: when an object is modified, the degree of influence on another object.

Low coupling: when an object is modified when an additional influence on the object compared to no effect.

High cohesion: one related to an object only to do their own thing. Single Responsibility Principle. (Such as creating a human being, just doing things people do)

 

to sum up:

Usage is the same combination of relations and relationships, that is a target as a member variable of another object

Combination: Overall - Local

Association: there is no causal relationship

Dependence: a target object as the other method parameters

 

 The relationship between objects and object

 1. Combination relationship

 1 by the target computer: hard disk object, memory object, the CPU objects, objects motherboard, display objects, etc.

 Car and tire - Combined 

 Reflect: Overall --- Local

 

 2. dependencies

 Girl with a cell phone, the girl is dependent on the phone.

 As a further object of a method of the object parameter.

 

 3. relationship

 An object as a member variable of another object, not a group relationship between them. That is not part of the overall relationship and.