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

Look out for these patterns in code:

• You see chained calls like:
  Product p = new ProductBuilder().setX().setY().build();
• Construction logic is encapsulated in a builder class.
• The main class has many optional fields.
• A Director may manage the building process in some implementations.

• When an object has many optional parameters.
• To avoid telescoping constructors.
• When object construction is complex or conditional.
• To create immutable objects cleanly.
• To improve code readability and maintainability.

Define the class to be built with required fields.

public class Car {
    private String make, model, color;
    private boolean hasSunroof;

    public Car(String make, String model, String color, boolean hasSunroof) {
        this.make = make;
        this.model = model;
        this.color = color;
        this.hasSunroof = hasSunroof;
    }
}

public class CarBuilder {
    private String make, model, color;
    private boolean hasSunroof;

    public CarBuilder setMake(String make) {
        this.make = make;
        return this;
    }

    public CarBuilder setModel(String model) {
        this.model = model;
        return this;
    }

    public CarBuilder setColor(String color) {
        this.color = color;
        return this;
    }

    public CarBuilder setSunroof(boolean hasSunroof) {
        this.hasSunroof = hasSunroof;
        return this;
    }

    public Car build() {
        return new Car(make, model, color, hasSunroof);
    }
}

Car car = new CarBuilder()
              .setMake("Toyota")
              .setModel("Camry")
              .setColor("Blue")
              .setSunroof(true)
              .build();

Start from how you want to use it:

Entity e = new EntityBuilder().setX().setY().build();

Then build your Entity class and EntityBuilder around it.

• Readable and intuitive object creation.
• Keeps objects immutable post-construction.
• Helps build different versions of the same object.
• Avoids constructor overload hell.

• Builder class: ClassNameBuilder
• Methods: setX(), withX(), addX()
• Finalizer method: build()

Builder Pattern helps you construct complex objects in a clean, step-by-step manner — no need to juggle dozens of constructor arguments.

Made with ❤️ by syedyshiraz