Subway.java

public class Subway {

    //Member Variables
    private String bread;
    private boolean toast;
    private boolean veg;
    private boolean nonVeg;
    private boolean onion;
    private boolean tomato;
    private boolean olives;
    private boolean chicken;
    private boolean mutton;
    private String cheese;


    //Constructor
    Subway(Builder builder) {
        this.bread = builder.bread;
        this.toast = builder.toast;
        this.veg = builder.veg;
        this.nonVeg = builder.nonVeg;
        this.onion = builder.onion;
        this.tomato = builder.tomato;
        this.olives = builder.olives;
        this.chicken = builder.chicken;
        this.mutton = builder.mutton;
        this.cheese = builder.cheese;
    }

    public String getBread() {
        return bread;
    }

    public boolean isToast() {
        return toast;
    }

    public boolean isVeg() {
        return veg;
    }

    public boolean isNonVeg() {
        return nonVeg;
    }

    public boolean isOnion() {
        return onion;
    }

    public boolean isTomato() {
        return tomato;
    }

    public boolean isOlives() {
        return olives;
    }

    public boolean isChicken() {
        return chicken;
    }

    public boolean isMutton() {
        return mutton;
    }

    public String getCheese() {
        return cheese;
    }

    public static Bread builder() {
        return new Builder();
    }


    //Builder class
    public static class Builder implements Bread, Toast, Type, Veg, NonVeg, Extra {

        private String bread;
        private boolean toast;
        private boolean veg;
        private boolean nonVeg;
        private boolean onion;
        private boolean tomato;
        private boolean olives;
        private boolean chicken;
        private boolean mutton;
        private String cheese;

        Builder() {
            this.bread = null;
            this.toast = false;
            this.veg = false;
            this.nonVeg = false;
            this.onion = false;
            this.tomato = false;
            this.olives = false;
            this.chicken = false;
            this.mutton = false;
            this.cheese = null;
        }

        public Toast bread(String bread) {
            this.bread = bread;
            return this;
        }

        public Type toast(boolean toast) {
            this.toast = toast;
            return this;
        }

        public Veg veg() {
            this.veg = true;
            return this;
        }

        public NonVeg nonVeg() {
            this.nonVeg = true;
            return this;
        }

        public Veg onion() {
            this.onion = true;
            return this;
        }

        public Veg tomato() {
            this.tomato = true;
            return this;
        }

        public Veg olives() {
            this.olives = true;
            return this;
        }

        public Extra prepare() {
            return this;
        }

        public Veg chicken() {
            this.chicken = true;
            return this;
        }

        public Veg mutton() {
            this.mutton = true;
            return this;
        }

        public Builder cheese(String cheese) {
            this.cheese = cheese;
            return this;
        }

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

    }


    interface Bread {

        Toast bread(String bread);
    }

    interface Toast {

        Type toast(boolean toast);
    }

    interface Type {

        Veg veg();

        NonVeg nonVeg();
    }

    interface Veg {

        Veg onion();

        Veg tomato();

        Veg olives();

        Extra prepare();
    }

    interface NonVeg {

        Veg chicken();

        Veg mutton();
    }

    //Any extra non mandatory items
    interface Extra {

        Extra cheese(String cheese);

        Subway build();
    }
}