• Jun 22, 2016
• in Development
• 5 min read

The builder pattern

The builder software design pattern is an object creation one. It's a great building block for classes with optional fields. It provides a maintainable and readable way to instantiate immutable classes with more than 3 or 4 fields. It greatly reduces the time developers needs to understand how to instantiate the class properly.

You have surely faced one day or another a code similar to the one below.

public class Person {
  private final String firstname;
  private final String lastname;
  private final String address;
  private final String zipCode;

  public Person(final String firstname, final String lastname) {
    this(firstname, lastname, "");
  }

  public Person(final String firstname, final String lastname, final String address) {
    this(firstname, lastname, address, "");
  }

  public Person(final String firstname, final String lastname, final String address, final String zipCode) {
    this.firstname = Preconditions.nonNull(firstname);
    this.lastname = Preconditions.nonNull(lastname);
    this.address = Preconditions.nonNull(address);
    this.zipCode = Preconditions.nonNull(zipCode);
  }
}