繼承

In this class diagram, the role name for "Collection_Book_Association" in its association with "Book" is "Collection_Book," indicating the role of the book in this association .

5. 繼續（Inheritance）

Conclusion

Composition is a stronger form of aggregation, representing a whole-part relationship where the lifecycle of the parts is tied to the whole. It is depicted using a filled diamond connecting the whole to its parts.

在這張類圖中，沒有顯著的束縛前提，但假如有，例如可以標註「{獨一}」來透露表現某個屬性必須是唯一的 .

1. Class

組合是一種更強的聚合關係，示意整體和部分的生命周期是溝通的。組合關係用實心菱形默示，連接整體和部分。

約束條件用於描述種別或關聯的額外限制前提。束縛前提凡是用花括號「{}」透露表現，標註在種別或聯系關系線旁邊。

UML class diagrams are essential tools in software engineering, helping developers understand and design system structures. Through this specific class diagram example, we can see how concepts such as classes, associations, aggregations, compositions, inheritance, multiplicity, role names, and constraints are applied in practice. Understanding these concepts is crucial for better system design and implementation .

• Class Name: Located at the top of the class box, usually in bold.
• Attributes: Located below the class name, describing the properties or data of the class.
• Methods: Located below the attributes, describing the behaviors or operations of the class.

In this class diagram, the classes "Borrow" and "Reserve" inherit from the class "Operation," indicating that they are types of operations and inherit the basic attributes and methods of the "Operation" class .

這條聯系關系線上標註了「0..12」，表示一本書最多可以有12個館藏記實 .

在這張類圖中，「書籍」和「館藏_書籍聯系關系」之間的聯系關系示意一本書可以有多個館藏記實。

7. Role Name

Key Concepts of UML Class Diagrams

Inheritance represents an "is-a" relationship, where a subclass inherits the attributes and methods of a superclass. It is depicted using a hollow arrow pointing from the subclass to the superclass.

Multiplicity describes the number of instances of a class that can be associated with a single instance of another class. It is usually annotated at both ends of the association line.

種別是UML類圖中的根基單元，代表系統中的一個實體或對象。每一個種別凡是包括以下幾個部門：

在這張類圖中，「借閱」和「預約」種別繼續自「操作」種別，表示它們都是操作的一種，並繼承了操作的根基屬性和方式 .

類圖（Class Diagram）是同一建模說話（UML）中的一種靜態構造圖，用於描寫系統的佈局。類圖是面向對象建模中的焦點東西，普遍運用於軟體工程中。

它經由過程展現系統中的種別、這些種別的屬性、方式和類別之間的關係，來扶助開辟者理解和設計系統的架構。

結論

2. 聯系關系（Association）

6. 多重性（Multiplicity）

擔當關係用空心箭頭默示，從子種別指向父種別。

擔當暗示種別之間的是否關係，子種別擔當父種別的屬性和方式。

Constraints describe additional rules or limitations on classes or associations. They are usually enclosed in curly braces "{}" and annotated near the class or association line.

聚合關係用空心菱形表示，毗連整體和部分。

聚合是一種特殊的關聯，暗示整體和部分的關係。

In this class diagram, the aggregation between "Collection" and "Collection_Book_Association" indicates that a collection record can contain multiple book association records .

A class is the basic unit in a UML class diagram, representing an entity or object within a system. Each class typically includes the following parts:

5. Inheritance

在這張類圖中，「館藏_書本聯系關系」種別在與「冊本」聯系關系時的腳色名稱為「館藏_書籍」，表示這個聯系關系中的冊本腳色 .

In this class diagram, we see classes such as "Book," "Collection," and "Collection_Book_Association." For example, the "Book" class includes attributes like ISBN, title, and author, along with methods like borrow and return .

8. Constraints

In this class diagram, the multiplicity between "Book" and "Collection_Book_Association" is "0..12," indicating that a book can have between 0 and 12 collection records .

2. Association

In this class diagram, the association between "Book" and "Collection_Book_Association" indicates that a book can have multiple collection records. The line is annotated with "0..12," meaning a book can have between 0 and 12 collection records .

1. 種別（Class）

7. 腳色名稱（Role Name）

UML (Unified Modeling Language) class diagrams are a graphical representation used to describe the classes in a system and their relationships. They are a crucial tool in software engineering, helping developers understand and design system structures. This article will use the following class diagram as a case study to explain the key concepts of UML class diagrams.

它是軟體工程中極度主要的工具，匡助開辟者理解和設計系統的結構。本文將以一張具體的類圖為案例，詳細解釋UML類圖的樞紐概念。

UML（統一建模說話，Unified Modeling Language）類圖是一種用於描述系統中各個種別及其關係的圖形表示方法。

聯系關系平常用實線毗連兩個種別，並可以在線上標註聯系關系的名稱和角色。

聯系關系描寫了類別之間的結構關係。

An association describes the structural relationship between classes. It is usually represented by a solid line connecting two classes and can include the name and roles of the association.

In this class diagram, there are no explicit constraints. However, if there were, for example, a constraint could be "{unique}" to indicate that a certain attribute must be unique .

A role name describes the role of a class in an association. It is usually annotated at the end of the association line near the class name.

3. Aggregation

8. 約束前提（Constraints）

In this class diagram, there is no explicit composition relationship. However, if there were one, for example, between "Library" and "Collection," it would indicate that when the library closes, all collection records would be deleted .

4. Composition

在這張類圖中，我們可以看到「書籍」、「館藏」、「館藏_書本聯系關系」等種別。例如，「書籍」種別包括ISBN、書名、作者等屬性，和借閱、歸還等方式 .

在這張類圖中，「館藏」和「館藏_書籍關聯」之間的聚合關係暗示一個館藏記錄可以包括多個書籍關聯紀錄 .

它是軟體工程中十分主要的對象，扶助開發者理解和設計系統的構造。

UML（統一建模語言，Unified Modeling Language）類圖是一種用於描寫系統中各個類別及其關係的圖形暗示方法。本文將以一張具體的類圖為案例，具體解釋UML類圖的關頭概念。

多重性描寫了種別之間關聯的數量關係。多重性通常標註在聯系關系線的兩頭，示意一個種別實例可以與若幹個另外一類別實例聯系關系。

Aggregation is a special type of association that represents a whole-part relationship. It is depicted using a hollow diamond connecting the whole to its parts.

角色名稱用於描寫聯系關系中的種別在聯系關系中的腳色。

角色名稱通常標註在聯系關系線的末端，接近種別名稱。

在這張類圖中，沒有明顯的組合關係，但如果有，例如「藏書樓」和「館藏」之間的關係可所以組合關係，表示圖書館封閉時，所有館藏紀錄也將被刪除 .

4. 組合（Composition）

• 種別名稱：位於種別框的最上方，平日以粗體顯示。
• 方式（Methods）：位於屬性下方，描寫種別的行為或操作。