How to Implement an Association Class in UML using Java

How do I implement an Association Class in UML using Java?

// Example of a UML Association Class implementation in Java
class Order {
    private Product product;
    private int quantity;
    // constructor, getters, setters
}

class Product {
    private String name;
    private double price;
    // constructor, getters, setters
}

class OrderDetail extends Order {
    private String orderDate;
    // additional fields and methods related to order details
}

In UML (Unified Modeling Language), an Association Class is used to define a relationship between two classes that also requires its own properties and behavior. This is beneficial in object-oriented programming as it encapsulates the relationship alongside any related attributes or methods.

// Implementation of an Association Class in UML in Java
class Order {
    private Product product;
    private int quantity;
    private OrderDetail orderDetail;
    // constructor, getters and setters
}

class Product {
    private String name;
    private double price;
    // constructors, getters and setters
}

class OrderDetail {
    private Order order;
    private String orderDate;
    // constructor, getters and setters
}

Causes

• Association classes are used when a relationship between classes has attributes or methods of its own.
• They help in creating a more organized design by grouping related data together.

Solutions

• Define a class that acts as the Association Class which will hold references to the associated classes.
• Add attributes specific to the relationship.
• Extend or specialize the association class when needed for further functionality.

Mistake: Misunderstanding the purpose of an association class, thinking it is just another type of class.

Solution: Remember that an association class represents a relationship that also has its own independent attributes and methods.

Mistake: Not implementing proper access modifiers, leading to poor encapsulation.

Solution: Use private fields with public getter and setter methods to ensure encapsulation and data integrity.