Java with Lombok – Avoid Boilerplate or Generated Code (like GET, SET, CONSTRUCT, COMPARE)

In this tutorial, you will compare the code between a “vanilla” approach (without library) and Lombok. With three classic use-cases: DTO (get, set, toString), Builder, Implementation (arg validation).

Steps

Examples
1. DTO
2. Implementation
3. Builder
Configure
1. Project (Maven)
2. IDE (Eclipse)

DTO Example

Avoid code like get(), set(), toString(), public() by using @Data, @RequiredArgsConstructor, @ToString.

DTO_Lombock.java

import java.util.Calendar;
import lombok.*;

@Data
@ToString(exclude =  {"id"})
@RequiredArgsConstructor
public class DTO_Lombock {
  @NonNull private Long id;
  @NonNull private String firstName;
  @NonNull private String lastName;
           private Calendar birthdate;
}

DTO_Vanilla.java

import java.util.Calendar;

public class DTO_Vanilla {
  private Long id;
  private String firstName;
  private String lastName;
  private Calendar birthdate;

  public DTO_Vanilla(Long id, String firstName, String lastName) {
    super();
    this.id = id;
    this.firstName = firstName;
    this.lastName = lastName;
  }

  @Override
  public String toString() {
    return "DTO_Vanilla(firstName=" + firstName + ", lastName=" + lastName + ", birthdate=" + birthdate + ")";
  }

  public Long getId() {
    return id;
  }

  public void setId(Long id) {
    this.id = id;
  }

  public String getFirstName() {
    return firstName;
  }

  public void setFirstName(String firstName) {
    this.firstName = firstName;
  }

  public String getLastName() {
    return lastName;
  }

  public void setLastName(String lastName) {
    this.lastName = lastName;
  }

  public Calendar getBirthdate() {
    return birthdate;
  }

  public void setBirthdate(Calendar birthdate) {
    this.birthdate = birthdate;
  }
}

DTOTest.java

import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;

public class DTOTest {

  @Test
  public void test_Vanilla() {
    DTO_Vanilla obj = new DTO_Vanilla(1492L, "Damien", "FREMONT");

    assertThat(obj.getId()).isEqualTo(1492L);
    assertThat(obj.getFirstName()).isEqualTo("Damien");
    assertThat(obj.getLastName()).isEqualTo("FREMONT");

    assertThat(obj.toString()).isEqualTo("DTO_Vanilla(firstName=Damien, lastName=FREMONT, birthdate=null)");
  }

  @Test
  public void test_Lombock() {
    DTO_Lombock obj = new DTO_Lombock(1492L, "Damien", "FREMONT");

    assertThat(obj.getId()).isEqualTo(1492L);
    assertThat(obj.getFirstName()).isEqualTo("Damien");
    assertThat(obj.getLastName()).isEqualTo("FREMONT");

    assertThat(obj.toString()).isEqualTo("DTO_Lombock(firstName=Damien, lastName=FREMONT, birthdate=null)");
  }

}

Implementation Example

Avoid code like Logger log = …, if(null==…),) by using @Log, @NonNull.

Implem_Lombock.java

import lombok.*;
import lombok.extern.java.Log;

@Log
@RequiredArgsConstructor
public class Implem_Lombock {
  @NonNull private String status;

  public String execute(@NonNull String arg) {
    log.info("Execute for arg=" + arg);
    return arg + " " + status;
  }
}

Implem_Vanilla.java

import java.util.logging.Logger;

public class Implem_Vanilla {
  private String status;

  private final static Logger log = Logger.getLogger(Implem_Vanilla.class.getName());

  public Implem_Vanilla(String status) {
    super();
    this.status = status;
  }

  public String execute(String arg) {
    if (arg == null)
      throw new NullPointerException("arg");
    log.info("Execute for arg=" + arg);
    return arg + " " + status;
  }
}

ImplemTest.java

import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;

public class ImplemTest {

  @Test
  public void test_Vanilla() {
    Implem_Vanilla obj = new Implem_Vanilla("suffix");

    String res = obj.execute("arg");
    assertThat(res).isEqualTo("arg suffix");

    try {
      obj.execute(null);
    } catch (NullPointerException e) {
      assertThat(e.getMessage()).contains("arg");
    }
  }

  @Test
  public void test_Lombock() {
    Implem_Lombock obj = new Implem_Lombock("suffix");

    String res = obj.execute("arg");
    assertThat(res).isEqualTo("arg suffix");

    try {
      obj.execute(null);
    } catch (NullPointerException e) {
      assertThat(e.getMessage()).contains("arg");
    }
  }
}

Buidler Example

The builder pattern implementation.

Builder_Lombock.java

import java.util.Calendar;
import lombok.*;

@Builder
@Getter
public class Builder_Lombok {
  private Long id;
  private String firstName;
  private String lastName;
  private Calendar birthdate;
}

Builder_Vanilla.java

public class Builder_Vanilla {
  private Long id;
  private String firstName;
  private String lastName;

  public Long getId() {
    return id;
  }

  public void setId(Long id) {
    this.id = id;
  }

  public String getFirstName() {
    return firstName;
  }

  public void setFirstName(String firstName) {
    this.firstName = firstName;
  }

  public String getLastName() {
    return lastName;
  }

  public void setLastName(String lastName) {
    this.lastName = lastName;
  }

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

  public static class Builder {
    private Builder_Vanilla obj;

    public Builder() {
      obj = new Builder_Vanilla();
    }

    public Builder id(Long arg) {
      obj.id = arg;
      return this;
    }

    public Builder firstName(String arg) {
      obj.firstName = arg;
      return this;
    }

    public Builder lastName(String arg) {
      obj.lastName = arg;
      return this;
    }

    public Builder_Vanilla build() {
      return obj;
    }
  }

}

BuilderTest.java

import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;

public class BuilderTest {

  @Test
  public void test_Vanilla() {
    Builder_Vanilla obj = Builder_Vanilla.builder() //
        .id(1492L) //
        .firstName("Damien") //
        .lastName("FREMONT") //
        .build();

      assertThat(obj.getId()).isEqualTo(1492L);
      assertThat(obj.getFirstName()).isEqualTo("Damien");
      assertThat(obj.getLastName()).isEqualTo("FREMONT");
  }

  @Test
  public void test_Lombock() {
    Builder_Lombok obj = Builder_Lombok.builder() //
        .id(1492L) //
        .firstName("Damien") //
        .lastName("FREMONT") //
        .build();

      assertThat(obj.getId()).isEqualTo(1492L);
      assertThat(obj.getFirstName()).isEqualTo("Damien");
      assertThat(obj.getLastName()).isEqualTo("FREMONT");
  }

}

Configure Project (Maven)

Add Lombok dependency to you Maven project config.

pom.xml

<project ...>
...
  <dependencies>
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.16.16</version>
    </dependency>
...

Configure IDE (Eclipse)

You need to add a plugin to your IDE, because the compilation-validator and autocomplete won’t work (Lombok generate code during compilation time, too soon for your IDE).

Go to official website, choose your IDE, then follow instructions.