# @Builder Lombok annotation

Paul Tomoiu

●

Lombok,

Spring Boot,

Examples

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Published 2022-12-03

The project Lombok is a popular Java library that is used to minimize/remove the boilerplate code.

For using Lombok, we need to add the Lombok dependency. My example is using Maven, so the dependency is the following:

<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
   <groupId>org.projectlombok</groupId>
   <artifactId>lombok</artifactId>
   <version>1.18.26</version>
   <scope>provided</scope>
</dependency>

Also, my example is using Spring Boot, and it is created by using Spring Initializr.

The @Builder annotation is used when we need to implement a builder of a class with less code.

Here are some examples of using the @Builder annotation.

I will create 2 "Employee" classes and for each I will define a specific builder.

Employee.class
package com.example.builder.employee;

import lombok.Builder;
import lombok.ToString;

@ToString
@Builder(toBuilder = true)
public class Employee {
    private String id;
    private String name;
    private String department;
    private int age;
}

Employee2.class
package com.example.builder.employee;

import lombok.Builder;
import lombok.ToString;

@Builder(builderMethodName = "myBuilder")
@ToString
public class Employee2 {
    private String id;
    private String name;
    private String department;
    private int age;
}

And here we can see how these builders can be used:

BuilderApplication.class
package com.example.builder;

import com.example.builder.employee.Employee;
import com.example.builder.employee.Employee2;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class BuilderApplication {

	public static void main(String[] args) {
		SpringApplication.run(BuilderApplication.class, args);
		System.out.println("Here starts Spring application !");

		Employee emp1 = Employee.builder()
				.id("ID-1212")
				.name("John")
				.age(23)
				.department("Finance")
				.build();

		Employee.EmployeeBuilder emp1Builder = emp1.toBuilder();

		Employee emp11 = emp1Builder
				.id("ID-1213")
				.name("Anna")
				.build();

		System.out.println("emp1/name="+emp1.toString());
		System.out.println("emp11/name="+emp11.toString());

		Employee2 emp2 = Employee2.myBuilder()
				.id("ID-1000")
				.name("Dan")
				.age(23)
				.department("Marketing")
				.build();

		System.out.println("emp2/name="+emp2.toString());

		System.out.println("------    END   ------");
	}
}

When we run the code we can see:

Here starts Spring application !
emp1/name=Employee(id=ID-1212, name=John, department=Finance, age=23)
emp11/name=Employee(id=ID-1213, name=Anna, department=Finance, age=23)
emp2/name=Employee2(id=ID-1000, name=Dan, department=Marketing, age=23)
------    END   ------

Process finished with exit code 0

Info

The builder name can be renamed, using builderMethodName. This feature is useful when you want to use "builder" method for adding more functionalities to the new "builderMethodName" method.
The @Builder annotation can be used at the method level as well, by adding @Builder(builderMethodName = "builder") annotation to a method.