Bridge Design pattern - Class Diagram

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Understanding the Bridge Pattern Structure

The Bridge Design Pattern decouples an abstraction from its implementation so that both can vary independently. In object-oriented modeling, understanding how these two hierarchies connect via UML class diagrams is crucial for building maintainable, loosely coupled architectures.

Rather than compounding dimensions into a single inheritance tree, the Bridge pattern splits the architecture into two parallel hierarchies connected by an aggregation/composition reference—the "Bridge".

Key Class Diagram Components

• Abstraction: Defines the high-level control interface and maintains a reference to an object of type Implementor.
• Refined Abstraction: Extends the base Abstraction to provide variant business logic while delegating core primitive work to the Implementor.
• Implementor (Interface): Declares the low-level, primitive operations common to all concrete implementations.
• Concrete Implementor: Implements the Implementor interface with platform- or vendor-specific execution logic.

UML Representation & Code Relationship

Here is a clean Java representation reflecting the exact structural relationship shown in the UML class diagram:

// Implementor Interface
interface Implementor {
    void implementationOperation();
}

// Concrete Implementors
class ConcreteImplementorA implements Implementor {
    @Override
    public void implementationOperation() {
        System.out.println("Executing ConcreteImplementorA operation.");
    }
}

class ConcreteImplementorB implements Implementor {
    @Override
    public void implementationOperation() {
        System.out.println("Executing ConcreteImplementorB operation.");
    }
}

// Abstraction (Bridge Connection)
abstract class Abstraction {
    protected Implementor implementor; // Composition bridge

    public Abstraction(Implementor implementor) {
        this.implementor = implementor;
    }

    public abstract void operation();
}

// Refined Abstraction
class RefinedAbstraction extends Abstraction {
    public RefinedAbstraction(Implementor implementor) {
        super(implementor);
    }

    @Override
    public void operation() {
        System.out.print("RefinedAbstraction delegating: ");
        implementor.implementationOperation();
    }
}

// Client Code
public class BridgeClassDiagramDemo {
    public static void main(String[] args) {
        Abstraction itemA = new RefinedAbstraction(new ConcreteImplementorA());
        itemA.operation();

        Abstraction itemB = new RefinedAbstraction(new ConcreteImplementorB());
        itemB.operation();
    }
}

Watch More Related Design Pattern Tutorials

• Bridge Design Pattern in Action: Real-Time Example with Shapes
• Bridge Design Pattern Implementation: LED TV Example
• Bridge Design Pattern Explained: Real-Time Message Publishing Use Case

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Bridge Design pattern - Class Diagram