uml-class.md

title
UML / Class Diagram

UML / Class Diagram

• Allen Holub: Training/Consulting/Programming: Agile, Architecture, Swift, Java http://www.holub.com/goodies/uml/#composition 各種案例的圖形 #ril

• 在何在 class diagram 表示 interface?? => 用 stereotype? 若圖表中沒有 realization/implementation，看不出誰是 interface。

• Class diagram - Wikipedia, the free encyclopedia 說明 class 的表示法 (切成三塊)、如何表示 visibility 與 scope。解釋了一些 relationship，最常用的是 dependency、generalization/inheritance、realization/implementation，至於 association、aggregation、composition 則還沒有搞懂?? #ril

• 某個 dependency 由 constructor 注入時，肯定會在內部保留 reference，這樣要用 dependency 或 association 來表示?

  • 按 https://en.wikipedia.org/wiki/Class_diagram 的說法，dependency 同時出現在 instance-level relationship 與 general relationship 裡，前者用在 dependency 由 constructor 注入時，內部會持有 dependency 的 refenece，也就是一種 association (實線)，通常會標上 <<use>>；後者 dependency 由 method parameter 傳入，只是短暫用到，就是單純的 dependency (虛線)。
  • DependencyAndAssociation - Martin Fowler https://martinfowler.com/bliki/DependencyAndAssociation.html 提到 association 隱含有 dependency 的意思 - if there is an association between two classes, there is also a dependency。事實上，UML 線條的畫法完全一樣，只差 dependency 可以加上 <<use>> 而已 (雖然大部份時候都不必要)

• Association、aggregation、composition 的差別??

  • uml - Difference between association, aggregation and composition - Stack Overflow http://stackoverflow.com/questions/885937/ 有用到就算一種 association，如果概念上有 "has" 的味道，就是 aggregration 或 composition，兩者的差異在於 composition 裡 owned object 無法獨立於 owing object 存在，但 aggregation 可以。
  • design - What is the difference between aggregation, composition and dependency? - Stack Overflow http://stackoverflow.com/questions/1644273/ #ril
  • Java Concepts & Interview Questions with Answers: Difference between Association, Aggregation & Composition for Java / UML (2011-08-22) http://www.javabench.in/2011/08/difference-between-association.html #ril
  • Understanding Association, Aggregation, and Composition - CodeProject (2012-03-15) https://www.codeproject.com/Articles/330447/Understanding-Association-Aggregation-and-Composit #ril
  • What is the difference between Association, Aggregation, and Composition? - Introduction to Object Oriented Programming Concepts (OOP) and More - CodeProject https://www.codeproject.com/articles/22769/introduction-to-object-oriented-programming-concep#Composition #ril

• UML basics: The class diagram (2004-09-15) #ril

• BallAndSocket - Martin Fowler (2005-02-03) https://martinfowler.com/bliki/BallAndSocket.html UML 2 開始支援用一個小圓 (o) 來表示 interface #ril

參考資料 {: #reference }

• UML Class Diagrams Reference