Software designer afternoon question

The first question is

Investigate ： Data flow diagram
First question ： How to answer questions , Watch the analysis 1-2 Graph , Combined with text , Get the missing entity
Second questions ： How to answer questions , Watch the analysis 1-2 Graph , Combined with the text description, the data storage name , Choose to add （ surface ） and （ file ） Equisuffix
Third questions ： How to answer questions ,

1. First step ： Parent graph and child graph balance （ Compare the difference between parent graph and child graph ）
2. The second step ： Processing has both input data and output data
3. Data conservation , Read the combination of text description and legend , See if there is any missing
   matters needing attention ：（ One end of the data flow must be processing ）

The second question is

Investigate ：ER Diagrams and relational patterns
First question ： How to answer questions （ There are several connections between reading and analysis ） Can I use a crude “ Contact number ” Instead of contact , Analyze what the connection is and the relationship 1:1 still 1：n perhaps n:m
Second questions ：
（1:1 when Situation 1 ： Contact independent ： Contact your own attributes and the primary keys of both parties . Situation two ： Merge the attributes of the connection to either party and the primary key of the other party ）
（1:n when Situation 1 : Contact independent ： Contact your own attributes and the primary keys of both parties . Situation two ： Merge the connection to multiple parties of the associated entity and add the primary key of the other party ）
（n:m when It can only be converted into an independent connection ： Contact your own attributes and the primary keys of both parties ,） Be careful ： Combined primary key
（ The transformation between superclass and subclass ： Add the primary key of the superclass to the subclass ）

1. Step one ： Read the description and properties given , See if there is any lack of explanation
2. Step two ： Analyze the relationship between entities to see if the other party's primary key is missing
   matters needing attention ： Primary key solid line , Foreign key dotted line , The independent connection is the combined primary key , Continuous solid line

Third question

Basic knowledge of ：
UML:UML There is 4 Kind of relationship : rely on 、 relation 、 Generalization and Implementation .
(1) rely on (Dependency). Dependency is the semantic relationship between two things , One of the things ( Independent things ) Hair
Change will affect another thing ( Depend on things ) The semantics of the . On the graph , Draw a dependency as a possible direction
Dotted line , Pictured 7-6 Shown .()

(2) relation (Association). Association is a kind of structural relationship , It describes the - - Group chain , A chain is a connection between objects .
Gather (Aggregation) Is a special type of Association , It describes the structural relationship between the whole and parts . Association and aggregation
The graphical representation of is shown in the figure 7-7 Sum graph 7-8 Shown . The degree of repetition can be marked on the Association (Multiplicity) And the character (Role).

Aggregation is a hollow diamond , And the combination is a solid diamond

(3) generalization (Generalization). Generalization is a special / General relationship , Special elements ( Subelement ) The object of can replace
Generation of general elements ( Parent element ) The object of . by this means , Child elements share the structure and behavior of the parent element . On the graph ,
Draw a generalized relationship as - A solid line with a hollow arrow , It points to the parent element , Pictured 7-9 Shown .

The parent class generalizes the child class （ Subclass inherits parent , Alternative inheritance ）

(4) Realization (Realization). Implementation is the semantic relationship between class elements , One class element is specified by another class element
A contract guaranteeing execution . Implementation relationships are used in both cases : A kind of Between interfaces and the classes or components that implement them ;
The other is between use cases and the collaboration that implements them . On the graph , Draw an implementation relationship as - - With a hollow arrow
Dotted line , Pictured 7-10 Shown .（ Less examination ）

Class diagram

Use case diagram

Inclusion relation

When triggering the included use case, it must touch the included use case

Extended relationship
When executing basic use cases , Trigger extended use cases （ Example ： Points will be deducted because of being late , Late arrival and points deduction ）

Question 6

// Access modifier 
private  Private   Code can only be accessed in this class 
protected  The protected   Code can be accessed in the same package and subclass .

// Non access modifier 
final  Immutable   This class cannot be inherited by other classes 
abstract  abstract   This class cannot be used to create objects ( To access abstract classes , Subclasses of abstract classes must be used )

interface  Interface