Spring @Lazy Annotation Example

🎓 Top 15 Udemy Courses (80-90% Discount): My Udemy Courses - Ramesh Fadatare — All my Udemy courses are real-time and project oriented courses.

▶️ Subscribe to My YouTube Channel (178K+ subscribers): Java Guides on YouTube

▶️ For AI, ChatGPT, Web, Tech, and Generative AI, subscribe to another channel: Ramesh Fadatare on YouTube

In this tutorial,  we will learn how to use @Lazy annotation in Spring or Spring boot applications.

YouTube Video

@Lazy Annotation Overview

By default, Spring creates all singleton beans eagerly at the startup/bootstrapping of the application context.

You can load the Spring beans lazily (on-demand) using @Lazy annotation. 

The @Lazy annotation can be used with @Configuration, @Component, and @Bean annotations.

Eager initialization is recommended: to avoid and detect all possible errors immediately rather than at runtime.

@Lazy Annotation Example

Let's create two classes and annotated them with @Component annotation.

EagerLoader

import org.springframework.stereotype.Component;

@Component
public class EagerLoader {

    public EagerLoader(){
        System.out.println("EagerLoader ..");
    }
}

LazyLoader

Note that we have annotated LazyLoader class with @Lazy annotation:

import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Component;

@Component
@Lazy
public class LazyLoader {

    public LazyLoader(){
        System.out.println("LazyLoader..");
    }
}

Testing

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringAnnotationsApplication {

	public static void main(String[] args) {
		var context = SpringApplication.run(SpringAnnotationsApplication.class, args);
		// EagerLoader eagerLoader = context.getBean(EagerLoader.class);
                LazyLoader lazyLoader = context.getBean(LazyLoader.class);
	}
}

Note that the EagerLoader class bean was created eagerly at the startup/bootstrapping of the application context but the LazyLoader class bean is created when it requested using the getBean() method:

                LazyLoader lazyLoader = context.getBean(LazyLoader.class);

This clearly demonstrates that @Lazy annotation is used to load the Spring beans lazily (on-demand).

Using @Value Annotation with @Configuration & @Bean Annotations

If you annotated @Lazy annotation with @Configuration annotation then all the beans within the configuration file are loaded lazily:

import net.javaguides.springannotations.lazy.EagerLoader;
import net.javaguides.springannotations.lazy.LazyLoader;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Lazy;

@Configuration
@Lazy
public class AppConfig {

    @Bean
    public LazyLoader lazyLoader(){
        return new LazyLoader();
    }

    @Bean
    public EagerLoader eagerLoader(){
        return new EagerLoader();
    }
}

If you annotated @Lazy annotation with @Bean annotation then that particular bean within the configuration file is loaded lazily:

    @Bean
    @Lazy
    public LazyLoader lazyLoader(){
        return new LazyLoader();
    }

Related Spring and Spring Boot Annotations

• Spring Boot @Bean Annotation Example
• Spring @Qualifier Annotation Example
• Spring @Autowired Annotation with Example
• Spring @Bean Annotation with Example
• Spring @Configuration Annotation with Example
• Spring @PropertySource Annotation with Example
• Spring @Import Annotation with Example
• Spring @ImportResource Annotation Example
• Spring - @Lazy Annotation Example
• Spring - @Primary Annotation Example
• Spring @PostConstruct and @PreDestroy Example
• Spring @Repository Annotation
• Spring @Service Annotation 
• The Spring @Controller and @RestController Annotations
• Spring Boot @Component, @Controller, @Repository and @Service
• Spring @Scope annotation with Prototype Scope Example
• Spring @Scope annotation with Singleton Scope Example
• Spring Boot @PathVariable
• Spring Boot @ResponseBody
• Spring @RequestBody - Binding Method Parameters to Request Body
• Spring Boot @ResponseStatus Annotation
• Spring Boot - Creating Asynchronous Methods using @Async Annotation
• @SpringBootTest Spring Boot Example
• @SpringBootTest vs @WebMvcTest
• @DataJpaTest Spring Boot Example
• Spring @PostConstruct and @PreDestroy Example
• Spring @GetMapping, @PostMapping, @PutMapping, @DeleteMapping and @PatchMapping
• Spring Boot @EnableAutoConfiguration Annotation with Example
• Spring Boot @SpringBootApplication Annotation with Example 

My Top and Bestseller Udemy Courses. The sale is going on with a 70 - 80% discount. The discount coupon has been added to each course below:

Build REST APIs with Spring Boot 4, Spring Security 7, and JWT

🆕 High-Demand 80–90% OFF

[NEW] Learn Apache Maven with IntelliJ IDEA and Java 25

🆕 High-Demand 80–90% OFF

ChatGPT + Generative AI + Prompt Engineering for Beginners

🚀 Trending Now 80–90% OFF

Spring 7 and Spring Boot 4 for Beginners (Includes 8 Projects)

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Building Real-Time REST APIs with Spring Boot - Blog App

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Building Microservices with Spring Boot and Spring Cloud

🌟 Top Rated 80–90% OFF
Available in Udemy for Business

Java Full-Stack Developer Course with Spring Boot and React JS

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Build 5 Spring Boot Projects with Java: Line-by-Line Coding

🌟 Top Rated 80–90% OFF

Testing Spring Boot Application with JUnit and Mockito

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Spring Boot Thymeleaf Real-Time Web Application - Blog App

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Master Spring Data JPA with Hibernate

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Spring Boot + Apache Kafka Course - The Practical Guide

🎓 Student Favorite 80–90% OFF
Available in Udemy for Business

Java Testing: Mastering JUnit 5 Framework

🆕 New 80–90% OFF

Reactive Programming in Java: Spring WebFlux and Testing

🌟 Top Rated 80–90% OFF

Spring Boot + RabbitMQ Course - The Practical Guide

🌟 Top Rated 80–90% OFF
Available in Udemy for Business

Functional Programming in Java (Includes Java Collections)

🎓 Student Favorite 80–90% OFF

ChatGPT for Java Developers: Boost Your Productivity with AI

🚀 Trending Now 80–90% OFF