Design Patterns in Java (Creational) - Builder Pattern

Builder Pattern

• Handle complex constructors
• Large number of parameters
• Immutability

• Ex

• LaunchBuilder is the static inner class
• Each method from LaunchBuilder is the equivalent to the setters
• In this way the result class "LauchOrder" cannot be modified, only have getters

public class LaunchOrder {

    

    public static class LaunchBuilder {

        private String bread;

        private String meat;

        private String dressing;

        private String condiments;

        public LaunchBuilder(){

        

        }

        

        public LaunchOrder build(){

            return new LaunchOrder(this);

        }

        

        public LaunchBuilder bread(String bread){

            this.bread = bread;

            return this;

        }

        public LaunchBuilder meat(String meat){

            this.meat = meat;

            return this;

        }

        public LaunchBuilder dressing(String dressing){

            this.dressing = dressing;

            return this;

        }

        public LaunchBuilder condiments(String condiments){

            this.condiments = condiments;

            return this;

        }

        

    }

    

   

    private final String bread;

    private final String meat;

    private final String dressing;

    private final String condiments;

     public LaunchOrder(LaunchBuilder lb){

         this.bread = lb.bread;

         this.meat = lb.meat;

         this.dressing = lb.dressing;

         this.condiments = lb.condiments;

     }

     

    public String getBread() {

        return bread;

    }

    public String getMeat() {

        return meat;

    }

    public String getDressing() {

        return dressing;

    }

    public String getCondiments() {

        return condiments;

    }

}

------------------ Main ----------------

public static void main(String[] args) {

        LaunchOrder.LaunchBuilder lb = new LaunchOrder.LaunchBuilder();

        

        lb.bread("pan de ajo").condiments("cebolla").meat("jamon");

        

        LaunchOrder lo = lb.build();

        

        System.out.println(lo.getBread());

    }