Builder.md

YouTube

Car.java

public class Car {
    private String name;
    private Integer year;
    private String color;

    @Override
    public String toString() {
        return "Car{" +
                "name='" + name + '\'' +
                ", year=" + year +
                ", color='" + color + '\'' +
                '}';
    }

    public Car(CarBuilder cb){
        this.name = cb.name;
        this.year = cb.year;
        this.color = cb.color;
    }

    public static class CarBuilder{
        private String name;
        private Integer year;
        private String color;

        public CarBuilder(String name) {
            this.name = name;
        }

        public CarBuilder setYear(Integer year){
            this.year = year;
            return this;
        }

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

        public Car build(){
            return new Car(this);
        }
    }
}

Main.java

public class Main {
    public static void main(String[] args) {
        Car.CarBuilder cb = new Car.CarBuilder("car1");

        Car car1 = cb.build();
        System.out.println(car1);

        Car car2 = cb.setColor("red").build();
        System.out.println(car2);

        Car car3 = cb.setYear(2024).build();
        System.out.println(car3);
    }
}

// Car{name='car1', year=null, color='null'}
// Car{name='car1', year=null, color='red'}
// Car{name='car1', year=2024, color='red'}