Class: is classified objects and abstract result, the properties and methods of a class included in the class.
Object: are instances of classes.
Relationships between classes: association, dependency, generalization, and interfaces implemented.
Association:
He embodies the two categories, one semantic level or between classes and interfaces strong dependencies, such as me and my friends;
This relationship is stronger than dependence, there is no chance of dependency relationship is not temporary, usually long-term, but also the general relationship between the two are equal;
Association can be unidirectional, bidirectional; code performance level, appear to be associated with the associated class A, class B as a class attribute, it may be associated with a class A type references are associated to class B global variables;
rely:
Can be simply understood, the use of A class is a class B to another, and this relationship is contingent use, the temporary, very weak, but the change will affect the type of A B; such a person to cross the river , need to borrow a boat, this time the relationship between the man and the boat is dependent;
Generalization:
It refers to a class (called a subclass, sub-interface) inherit another class (called the parent, the parent Interface) functions, and can increase the capacity of its own new features, inheritance is a class with a class or interface the most common relationship between the interfaces;
Interface and implementation:
Mainly for interfaces and abstract classes, the class that implements an interface and an abstract class must implement their approach;
By establishing an association between the class and the class, the class shown in FIG.
By class diagram may better understand and standardize the system is a model system, it has a great effect.