Builder creational design pattern with Lombok

The basics of lombok annotations

package com.basic.example;

import lombok.*;

@Getter
@Setter
/*
Use @Data which Combines @Getter, @Setter, @ToString, @EqualsAndHashCode, and @NoArgsConstructor
for all fields in the class.
 */
// "runtime", "director" use comma separated list to exclude multiple values.
@EqualsAndHashCode(exclude = {"runtime"}) // Exclude the 'runtime' field from equality check.
@ToString
/*
@ToString annotation in Lombok hides the actual implementation of the toString() method.
You won't see the generated code in your Java source file.
@Override
public String toString() {
  return "com.basic.example.Movies(name=" + name + ", year=" + year + ", runtime=" + runtime + ")";

 */
public class Movies {

    String name;
    int year;
    double runtime;

    /*
    @NonNull
    Exception in thread "main" java.lang.NullPointerException: ID is marked non-null but is null
    This will throw above exception, if we set this value as null , movies2.setID(null);
     */
    @NonNull
    private String ID;


}

@NonNull:
Ensures that the field cannot be set to null.
If you try to instantiate ID with a null value, it will throw a NullPointerException at runtime.

We can preview the code that generated from Lombok by right click on Movies class Refactor > Delombok and select the method that wish to preview. Select All lombok annotation value to see for all.

In main class

package com.basic.example;

public class Home {

    public static void main(String[] args) {
        Movies movies1 = new Movies();
        movies1.setName("Titanic");
        movies1.setYear(1996);
        movies1.setRuntime(195.5); // Runtime in minutes theatrical version
        movies1.setID("PARA-01");

        Movies movies2 = new Movies();
        movies2.setName("Titanic");
        movies2.setYear(1996);
        movies2.setRuntime(345.12); // Runtime in minutes Director cuts version
        movies1.setID("PARA-02");


        System.out.println(movies1.equals(movies2)); // Output: true

        // Using the generated toString() method
       System.out.println(movies1.toString());


    }
}

Output-

false
Movies(name=Titanic, year=1996, runtime=195.5, ID=PARA-02)

Builder creational design pattern with Lombok

package com.builder.example;

import lombok.Builder;
import lombok.Data;
import lombok.NonNull;

@Data
@Builder
public class Person {
    private String name;
    private int age;
    private String address;
    @NonNull // Here I marked ID as a not null field so it must be defined can't be null or empty
    private String ID;

    /*
We annotate the Person class with @Builder.
Lombok generates a builder class named PersonBuilder within the Person class,
which provides methods for setting each field individually.
     */
}

Main class

package com.builder.example;

public class MainBuilderPerson {

    public static void main(String[] args) {
        Person person=Person.builder().name("John doe").age(44).address("PO BOX 666,Kansas").ID("V-666").build();

        Person female=Person.builder().name("Jane doe").age(23).ID("V-666").build();

        System.out.println(person);
        System.out.println(female);

        /*
        In the main() method, we use the generated builder to construct a Person object by chaining method calls to set the desired fields.
        The build() method finalizes the construction of the Person object.
        This allows for a concise and readable way to construct objects, especially when dealing with classes that have many optional parameters.
        with the builder pattern generated by Lombok's @Builder, you can specify values only for the parameters you want to set, leaving the rest with their default values or null if no default values are provided.
         */
        System.out.println(person.equals(female)); // Output: false
    }
}

Output

Person(name=John doe, age=44, address=PO BOX 666,Kansas, ID=V-666)
Person(name=Jane doe, age=23, address=null, ID=V-666)
false

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>LombokJavaDemo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>14</maven.compiler.source>
        <maven.compiler.target>14</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>LATEST</version>  <scope>provided</scope>
        </dependency>
    </dependencies>

</project>