How to implement the builder pattern in Java 8?

Question

Implement the builder pattern prior to Java 8 has lots of tedious, nearly duplicated code; the builder itself is typically boilerplate code. Some duplicate code detectors co

Answer 1

We can use Consumer functional interface of Java 8 to avoid multiple getter/setter methods.

Refer the below-updated code with Consumer interface.

import java.util.function.Consumer;

public class Person {

    private String name;

    private int age;

    public Person(Builder Builder) {
        this.name = Builder.name;
        this.age = Builder.age;
    }

    @Override
    public String toString() {
        final StringBuilder sb = new StringBuilder("Person{");
        sb.append("name='").append(name).append('\'');
        sb.append(", age=").append(age);
        sb.append('}');
        return sb.toString();
    }

    public static class Builder {

        public String name;
        public int age;

        public Builder with(Consumer function) {
            function.accept(this);
            return this;
        }

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

    public static void main(String[] args) {
        Person user = new Person.Builder().with(userData -> {
            userData.name = "test";
            userData.age = 77;
        }).build();
        System.out.println(user);
    }
}

Refer the below link to know the detailed information with the different examples.

https://medium.com/beingprofessional/think-functional-advanced-builder-pattern-using-lambda-284714b85ed5

https://dkbalachandar.wordpress.com/2017/08/31/java-8-builder-pattern-with-consumer-interface/