Java Lombok: Omitting one field in @AllArgsConstructor?

Question

If I specify @AllArgsConstructor using Lombok, it will generate a constructor for setting all the declared (not final, not static) fields. Is it possible to omit some field and this leave generated constructor for all other fields?

Answer 1

No that is not possible. There is a feature request to create a @SomeArgsConstructor where you can specify a list of involved fields.

Full disclosure: I am one of the core Project Lombok developers.

Answer 2

Alternatively, you could use @RequiredArgsConstructor. This adds a constructor for all fields that are either @NonNull or final.

See the documentation

Answer 3

Just in case it helps, initialized final fields are excluded.

@AllArgsConstructor
class SomeClass {
    final String s;
    final int i;
    final List<String> list = new ArrayList<>(); // excluded in constructor
}

var x = new SomeClass("hello", 1);

It makes sense especially for collections, or other mutable classes.

This solution can be used together with the other solution here, about using @RequiredArgsConstructor:

@RequiredArgsConstructor
class SomeClass2 {
    final String s;
    int i; // excluded because it's not final
    final List<String> list = new ArrayList<>(); // excluded because it's initialized
}

var x = new SomeClass2("hello");

Answer 4

A good way to go around it in some cases would be to use the @Builder

Answer 5

This can be done using two annotations from Lombok:

• @RequiredArgsConstructor
• @NonNull

Please find the example as follows:

package com.ss.model;

import lombok.*;

@Getter
@Setter
@RequiredArgsConstructor
@ToString
public class Employee {

    private int id;

    @NonNull
    private String firstName;

    @NonNull
    private String lastName;

    @NonNull
    private int age;

    @NonNull
    private String address;
}

And then you can create an object as shown below:

Employee employee = new Employee("FirstName", "LastName", 27, "Address");

Answer 6

Lombok is meant to take care of the boilerplate code for your POJOs. Customized constructors/setters/getters/toString/copy etc are not on the boilerplate side of code. For these cases, every Java IDE provide easy to use code generators to help you do things in no time. In your case a

public MyClass(String firstName, String lastName) {....}

is much more readable and makes more sense than a hypothetic:

@AllArgsConstructor(exclude = "id", exclude = "phone")

Have fun!

Answer 7

When you needs a constructor with just some attributes, you can use

@RequiredArgsConstructor at class level and declare the choosed attributes as final. Then, if you need an empty constructor, you can use something like

@NoArgsConstructor(access=AccessLevel.PRIVATE, force=true)

This annotation will create an empty JPA's constructor and the attributes will be initialized with default values (0 for int, null for String and so on).

Example:

@Data
@Entity
@Table(name = "VetFiles")
@RequiredArgsConstructor
@NoArgsConstructor(access=AccessLevel.PRIVATE, force=true)
public class FileInfo implements Serializable {

    private static final long serialVersionUID = 6719621520531075147L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    private final String name;
    private final String url;

    @ManyToOne
    private Thing thing;