Builder Design Pattern

The Builder Design Pattern is a creational design pattern used to construct complex objects step-by-step. It separates the construction of a complex object from its representation, allowing the same construction process to create different representations.

🔧 Definition

Builder Pattern allows you to create different types and representations of an object using the same construction code.

🧱 When to Use It

Use the Builder Pattern when:

1. You want to construct a complex object step by step.

2. You want to create different representations of an object using the same building process.

3. The construction process must allow different representations or configurations.

🏗️ Structure

1. Product

• The complex object under construction.

2. Builder (Abstract)

• Specifies an abstract interface for creating parts of a object.

3. ConcreteBuilder

• Implements the interface.

• Keeps track of the product being built.

• Provides an interface to retrieve the final product.

4. Director

• Constructs an object using the interface.

• Orchestrates the building steps.

5. Client

• Configures the builder and director and retrieves the final product.

🔁 UML Diagram

🧑‍💻 Code Example (Java-like Pseudocode)

Step 1: Product

Step 2: Builder

Step 3: Concrete Builder

Step 4: Director

Step 5: Client

✅ Benefits

• Constructs complex objects step-by-step.

• Code is more readable and flexible.

• Different representations of a product can be created.

❌ Drawbacks

• Requires creating many classes.

• Might be overkill for simple objects.

🧩 Real-World Examples

• StringBuilder in Java/C#

• Builder in Lombok (Java) for constructing POJOs.

• Document builders like HTML/XML builders.

• UI builders in game engines and mobile apps.

🆚 Builder vs Factory

For more info https://www.geeksforgeeks.org/system-design/builder-design-pattern/