How to Build Objects with Any Number of Fields Using SpringBoot, Lombok, and @Builder

When a class has many attributes and different business scenarios require setting only a subset of those attributes, traditional constructors quickly become unwieldy because each combination would need its own overload.

Using Lombok's @Builder annotation generates a builder class that lets developers set any combination of fields in a readable, chainable way, eliminating the need for numerous constructors.

First, add Lombok to the project’s Maven dependencies:

<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.0</version>
</dependency>

Then define the domain class with the relevant Lombok annotations:

package com.ruoyi.demo.domain;

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class Student {
    private String name;
    private int age;
    private String sex;
    private String grade;
}

The annotations have the following effects:

@Data : generates getters, setters, toString, equals, and hashCode.

@AllArgsConstructor : creates a constructor with all fields.

@NoArgsConstructor : creates a no‑argument constructor.

@Builder : produces a builder API that implements the Builder pattern for the class.

Object creation now becomes concise:

Student student = Student.builder()
        .name("霸道的程序猿")
        .age(3)
        .sex("男")
        .build();

Student student1 = Student.builder()
        .name("霸道的程序猿")
        .age(3)
        .build();

System.out.println(student);
System.out.println(student1);

Each call to builder() can set only the fields needed for the specific scenario, and the resulting objects are printed via the generated toString method.