Builder Pattern

The Builder Pattern is a creational design pattern that provides a flexible solution for constructing complex objects. It allows you to create different representations of an object using the same construction code.

• Encapsulation of object creation logic.
• Separation of construction and representation.
• Ability to create complex objects step-by-step.

Use the Builder Pattern when:

• Object construction involves multiple steps.
• The object needs to be created with different representations.
• You want to avoid constructor telescoping (many parameters).

4.1 Step-by-Step Implementation

class Product {
    private String partA;
    private String partB;

    public void setPartA(String partA) {
        this.partA = partA;
    }

    public void setPartB(String partB) {
        this.partB = partB;
    }
}

class Builder {
    private Product product;

    public Builder() {
        this.product = new Product();
    }

    public Builder buildPartA(String partA) {
        product.setPartA(partA);
        return this;
    }

    public Builder buildPartB(String partB) {
        product.setPartB(partB);
        return this;
    }

    public Product build() {
        return product;
    }
}
            

In this example, the Builder class is used to construct a Product step-by-step.

When implementing the Builder Pattern, consider the following:

• Keep builder methods fluent by returning the builder itself.
• Ensure the build method returns the final product.
• Use a static inner class for the builder to encapsulate the logic.