Builder - Creational Design Pattern - Hello, world! I'm Anvay

👷 Builder

Allows you to create different flavors of an object while avoiding constructor pollution. Useful when there could be several flavors of an object. Or when there are a lot of steps involved in creation of an object. This is useful to create fluent API’s Example:

class Burger {
    protected int size;
    protected boolean cheese = false;
    protected boolean pepperoni = false;
    protected boolean lettuce = false;
    protected boolean tomato = false;
    public Burger(BurgerBuilder builder) {
        this.size = builder.size;
        this.cheese = builder.cheese;
        this.pepperoni = builder.pepperoni;
        this.lettuce = builder.lettuce;
        this.tomato = builder.tomato;
    }
}
class BurgerBuilder {
    public int size;
    public boolean cheese = false;
    public boolean pepperoni = false;
    public boolean lettuce = false;
    public boolean tomato = false;
    public BurgerBuilder(int size) {
        this.size = size;
    }
    public boolean addPepperoni() {
        this.pepperoni = true;
        return this;
    }
    public boolean addLettuce() {
        this.lettuce = true;
        return this;
    }
    public boolean addCheese() {
        this.cheese = true;
        return this;
    }
    public boolean addTomato() {
        this.tomato = true;
        return this;
    }
    public Burger build() {
        return new Burger(this);
    }
}
// usage:
Burger burger = (new BurgerBuilder(14))
                    .addPepperoni()
                    .addLettuce()
                    .addTomato()
                    .build();

When to use? When there could be several flavors of an object and to avoid the constructor telescoping. The key difference from the factory pattern is that; factory pattern is to be used when the creation is a one step process while builder pattern is to be used when the creation is a multi step process.