/**
 * Example of an immutable pojo with a built-in builder. (getters left out for brevity)
 * Admittedly most of the ugliness comes from the syntactic cruft of Java's way of doing closures
 * and the lack of method aliases. Scala translation is here: http://pastebin.com/TASbJC5y
 * I think this kind of builder could be automatically generated by a compile-time tool - for
 * my next trick I'll write one.
 * @author twitter.com/benhardy
 */
public final class PersonFeatures {
    public final int userId;
    public final int age;
    public final int children;
    public final int dogs;

    private PersonFeatures(int userId, int age, int children, int dogs) {
        this.userId = userId;
        this.age = age;
        this.children = children;
        this.dogs = dogs;
    }

    // give each stage of the builder only one callable method,
    // which returns the next stage

    public interface BuilderUserIdSpec {
        public BuilderAgeSpec userId(int v);
    }
    public interface BuilderAgeSpec {
        public BuilderChildrenSpec age(int v);
    }
    public interface BuilderChildrenSpec {
        public BuilderDogsSpec children(int v);
    }
    public interface BuilderDogsSpec {
        public BuilderFinal dogs(int v);
    }
    public interface BuilderFinal {
        public PersonFeatures build();
    }

    /* the builder method returns its first stage which allows you to set userId, and so on */

    public static BuilderUserIdSpec builder() {
        return new BuilderUserIdSpec() {
            @Override public BuilderAgeSpec userId(final int _userId) {
                 return new BuilderAgeSpec() {
                     @Override public BuilderChildrenSpec age(final int _age) {
                         return new BuilderChildrenSpec() {
                             @Override public BuilderDogsSpec children(final int _children) {
                                 return new BuilderDogsSpec() {
                                     public BuilderFinal dogs(final int _dogs) {
                                         return new BuilderFinal() {
                                            @Override public PersonFeatures build() {
                                                return new PersonFeatures(_userId, _age, _children, _dogs);
                                            }
                                         };
                                     }
                                 };
                             }
                         };
                     }
                 };
            }
        };
    }

    /**
     * example usage. pretty obvious what is going on. only one way to do it. IDE will help.
     */
    public static void main(String[]args) {
        PersonFeatures person = PersonFeatures.builder().userId(4437).age(22).children(0).dogs(1).build();
    }
}