Class Diagrams

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Figure 4.1. An association between a player and a team.
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real meaning of association?
• What is the real meaning of class A associate with class B?
– Answer: class A has a attribute of class B.
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Figure 4.13. In a reflexive association, you draw the line from the class to itroles, association name, direction of the association, and multiplicity.
The class of Player has an attribute of class of Team The class of Team has an attribute of the class Player
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Figure 4.4. Several classes can associate with a particular class.
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Example: A Table • The Legs & TableTop belong to just the specific table. • Only if the table is consisted of components, but is not consisted in whole.
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2.4 Aggregations, Composites,
• Actually it is also a kind of association. • It can use association to depict Aggregations.
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2.4.1 Aggregations 聚合
• Sometimes a class consists of a number of component classes. This is a special type of relationship called an aggregation. • The components and the class they constitute are in a part-whole association. • 聚合的属性和方法啥样？？Component和 composite类的属性和方法。
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Constraints on Associations
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Constraints on Associations
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Association Classes
• An association can have attributes and operations, just like a class. In fact, when this is the case, you have an association class.
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Constraints on Aggregations
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2.4.2 Composites
• A composite is a strong type of aggregation. • Each component in a composite can not belong to some other composite. • Sometimes a component in a composite doesn't last as long as (shorter than) the composite. • If the composite object is gone, so does the component.
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It is in an association
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Figure 4.10. Possible multiplicities and how to represent them in the UML.
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Reflexive Associations
• Sometimes, a class is in an association with itself.
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2.3 Dependencies 依赖
• In a different kind of relationship, one class uses another. This is called a dependency. • The most common usage of a dependency is to show that the signature of one class's operation uses another class.
– Associations
• Multiplicity • Aggregations, • Composites
– Dependency
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2.1 Associations 关联
• When classes are connected together conceptually, the connection is called an association. • When class A associate with class B, we call it association.
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1. Sum up the classes
relationships
• Horizontal (no derivative) class relationships — not from the perspective of physical layout • Vertical (derivative) class relationships — not from the perspective of physical layout
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Figure 5.3. In a composite, each component belongs to exactly one whole. A closed diamond represents this relationship.
• derivative relationship
– Inheritance and Generalization – Interfaces and Realizations
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2. Horizontal class relationships
• not a derivative relationship
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Figure 2.12. In a composition, a component can sometimes die out before the composite does. //UML diagram
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Example: Attacking Rover
• Red_Side object and Blue_Side object each have 5 Rovers. • If the Red_Side’s object is gone, so is the Rovers which Red_Side possess. • The individual Rover will die before the Red_Side object die. • That is why we say that sometimes a component doesn't last as long as the composite (it is gone earlier).
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Links used in the object diagram
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2.2 Multiplicity
//it is to refine an association
• the number of objects from one class that relate with a single object in an associated class( in an association). • It is to tell number of objects from one class associate objects from another class.
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Example: A Tree • The leaf can not belong to some other tree. • The leaves on a tree can die out before the tree does. • If the tree dies, so does the leaves from it. • Diagram: the tree is composite of trunk, leaf, branches???
Class Diagrams
By He, Suoju
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Overview
1. 2. 3. 4. 5. 6. Sum up the classes relationships Horizontal class relationships 横向 Vertical class relationships 纵向 Visibility When to use Class Diagrams Demo the class relationships with Rational Rose
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Association Classes
(is it possible to model it using modeling tools? Not yet)
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Links
• Link is an instance of association. Just as an object is an instance of a class, an association has instances as well. • If you imagine a specific player who plays for a specific team, the Plays on relationship is called a link, and you represent it as a line connecting two objects. Just as you would underline the name of an object, you underline the name of a link, as in Figure 4.8.