java-pojobuilder's Introduction

Java - POJO Builder

A Java code generator for the builder pattern using annotation processing

Usage

Just annotate your POJOs with the @Builder annotation, like so:

@Builder
public class User {
  String name;
  int age;
  Address address;
}

@Builder
public class Address {
  String street;
  String postcode;
  String city;
}

When you compile your project, a new Builder class will be generated for each annotated POJO, like so:

public final class UserBuilder {

  private String name;
  private int age;
  private Address address;

  public static UserBuilder user() {
    return new UserBuilder();
  }

  public static UserBuilder user(User from) {
    UserBuilder builder = new UserBuilder();
    builder.name = from.name;
    builder.age = from.age;
    builder.address = from.address;
    return builder;
  }

  public UserBuilder name(String name) {
    this.name = name;
    return this;
  }

  public UserBuilder age(int age) {
    this.age = age;
    return this;
  }

  public UserBuilder address(Address address) {
    this.address = address;
    return this;
  }

  public UserBuilder address(AddressBuilder addressBuilder) {
    this.address = addressBuilder.build();
    return this;
  }

  public User build() {
    User user = new User();
    user.name = name;
    user.age = age;
    user.address = address;
    return user;
  }
}

Using static imports, you can then create those objects as simple as:

User user = user()
  .name("Bob The Builder")
  .age(25)
  .address(
      address()
      .street("10 Hight Street")
      .postcode("WC2")
      .city("London"))
  .build();

Fields annotated with @Ignore will be ignored.

Example

Check out the sample project for an example implementation.

The sample project is currently an Android module, but it should work with a pure Java project just as well. If somebody knows how to setup an annotation processor for a Java module using Gradle, please let me know. The apt plugin currently supports only Android modules.

Download

Grab it via Gradle:

compile 'com.jenzz.pojobuilder:api:1.0'
apt 'com.jenzz.pojobuilder:processor:1.0'

You only need to include the api module (contains just the annotations) as a real dependency.

The annotation processor module can be a compile time only dependency. To do that I highly recommend using Hugo Visser's great apt plugin.

License

This project is licensed under the MIT License.

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