Chapter 2
1. How do I express multiple features?
A: At one end of the correlated line, you can specify how many remote objects can be associated with the number of objects in the near end.
2. How to discover the inheritance relationships between classes?
A: In the class list of the initial model, find two or more classes with the same attributes and operations. One of these classes may be the father of another class, or
You can create a parent class for these classes.
3. What is an abstract class?
A: the abstract class is used as the base class in the inheritance level, but it does not generate instance objects.
4. What are the functions of a qualifier?
A: The qualifier is used to unassociate one-to-multiple pairs into one-to-one pairs.
Chapter 2
1. What is the difference between clustering and composition?
A: Composition and clustering are the whole-part association between the whole class and the part. In clustering, some may belong to multiple components. In composition, some functions belong to one whole.
2. What is implementation? What are the similarities between implementation and inheritance? What are the differences between the two?
A: The implementation is the relationship between the class and its interfaces. It can be said that the class implements its interface. Implementation and inheritance are similar in that the class can use the operations in its interface or operate or
Inherit the operation from the parent class. The difference between the two is that the class cannot use the attributes in its interface but can inherit the attributes of the parent class. (?)
3. Write the names of the three visibility levels and describe the meaning of each visibility level?
If the attribute or operation of a class has public visibility, you can use the attribute or operation of this class in another class.
If the attributes or operations of a class have the protected visibility, the subclass or other descendants of the class can use the attributes or operations in the class.
If a class's attributes or operations have private visibility, only the classes with its attributes and operations can use them.
All operations in the interface have public visibility.
Chapter 2
1. What is the external entity that initiates a case called?
A: The external entity that initiates the use case is called the participant actor.
2. What is the meaning of the included use case?
A: "include a use case" means that some steps in a use case are the same as those in another use case.
Therefore, you only need to specify the use cases included in the use case, instead of listing all scenarios of the use case.
3. What is the meaning of the extended use case?
A: an extended use case refers to adding steps to the use case. In this way, a new use case can be generated.
4. Are use cases and scenarios the same concept?
A: No. Use cases are a set of scenarios.
Chapter 2
1. List the two advantages of visualized use cases.
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