Baeldung Pro comes with both absolutely No-Ads as well as finally with Dark Mode, for a clean learning experience:
Once the early-adopter seats are all used, the price will go up and stay at $33/year.
Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.
Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.
To learn more about Java features on Azure Container Apps, visit the documentation page.
You can also ask questions and leave feedback on the Azure Container Apps GitHub page.
Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.
Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.
To learn more about Java features on Azure Container Apps, you can get started over on the documentation page.
And, you can also ask questions and leave feedback on the Azure Container Apps GitHub page.
Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.
Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.
With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.
Try a 14-Day Free Trial of Orkes Conductor today.
Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.
Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.
With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.
Try a 14-Day Free Trial of Orkes Conductor today.
Mocking is an essential part of unit testing, and the Mockito library makes it easy to write clean and intuitive unit tests for your Java code.
Get started with mocking and improve your application tests using our Mockito guide:
Handling concurrency in an application can be a tricky process with many potential pitfalls. A solid grasp of the fundamentals will go a long way to help minimize these issues.
Get started with understanding multi-threaded applications with our Java Concurrency guide:
Spring 5 added support for reactive programming with the Spring WebFlux module, which has been improved upon ever since. Get started with the Reactor project basics and reactive programming in Spring Boot:
Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.
But these can also be overused and fall into some common pitfalls.
To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:
Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:
Yes, Spring Security can be complex, from the more advanced functionality within the Core to the deep OAuth support in the framework.
I built the security material as two full courses - Core and OAuth, to get practical with these more complex scenarios. We explore when and how to use each feature and code through it on the backing project.
You can explore the course here:
All Access is finally out, with all of my Spring courses. Learn JUnit is out as well, and Learn Maven is coming fast. And, of course, quite a bit more affordable. Finally.
>> GET THE COURSE
Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.
Get started with Spring Data JPA through the guided reference course:
End-to-end testing is a very useful method to make sure that your application works as intended. This highlights issues in the overall functionality of the software, that the unit and integration test stages may miss.
Playwright is an easy-to-use, but powerful tool that automates end-to-end testing, and supports all modern browsers and platforms.
When coupled with LambdaTest (an AI-powered cloud-based test execution platform) it can be further scaled to run the Playwright scripts in parallel across 3000+ browser and device combinations:
Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:
Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:
1. Overview
In this quick tutorial, we’ll discuss Spring’s @Primary annotation which was introduced with version 3.0 of the framework.
Simply put, we use @Primary to give higher preference to a bean when there are multiple beans of the same type.
Let’s describe the problem in detail.
2. Why Is @Primary Needed?
In some cases, we need to register more than one bean of the same type.
In this example we have JohnEmployee() and TonyEmployee() beans of the Employee type:
@Configuration
public class Config {
@Bean
public Employee JohnEmployee() {
return new Employee("John");
}
@Bean
public Employee TonyEmployee() {
return new Employee("Tony");
}
}Spring throws NoUniqueBeanDefinitionException if we try to run the application.
To access beans with the same type we usually use @Qualifier(“beanName”) annotation.
We apply it at the injection point along with @Autowired. In our case, we select the beans at the configuration phase so @Qualifier can’t be applied here. We can learn more about @Qualifier annotation by following the link.
To resolve this issue Spring offers the @Primary annotation.
3. Use @Primary With @Bean
Let’s have a look at configuration class:
@Configuration
public class Config {
@Bean
public Employee JohnEmployee() {
return new Employee("John");
}
@Bean
@Primary
public Employee TonyEmployee() {
return new Employee("Tony");
}
}We mark TonyEmployee() bean with @Primary. Spring will inject TonyEmployee() bean preferentially over the JohnEmployee().
Now, let’s start the application context and get the Employee bean from it:
AnnotationConfigApplicationContext context
= new AnnotationConfigApplicationContext(Config.class);
Employee employee = context.getBean(Employee.class);
System.out.println(employee);After we run the application:
Employee{name='Tony'}From the output, we can see that the TonyEmployee() instance has a preference while autowiring.
4. Use @Primary With @Component
We can use @Primary directly on the beans. Let’s have a look at the following scenario:
public interface Manager {
String getManagerName();
}We have a Manager interface and two subclass beans, DepartmentManager:
@Component
public class DepartmentManager implements Manager {
@Override
public String getManagerName() {
return "Department manager";
}
}And the GeneralManager bean:
@Component
@Primary
public class GeneralManager implements Manager {
@Override
public String getManagerName() {
return "General manager";
}
}They both override the getManagerName() of the Manager interface. Also, note that we mark the GeneralManager bean with @Primary.
This time, @Primary only makes sense when we enable the component scan:
@Configuration
@ComponentScan(basePackages="org.baeldung.primary")
public class Config {
}Let’s create a service to use dependency injection while finding the right bean:
@Service
public class ManagerService {
@Autowired
private Manager manager;
public Manager getManager() {
return manager;
}
}Here, both beans DepartmentManager and GeneralManager are eligible for autowiring.
As we marked GeneralManager bean with @Primary, it will be selected for dependency injection:
ManagerService service = context.getBean(ManagerService.class);
Manager manager = service.getManager();
System.out.println(manager.getManagerName());The output is “General manager”.
5. Clarification on Bean Naming
In addition, when using the @Primary annotation, it’s important to ensure that each bean name is unique within the context. Spring uses the method name as the default bean name. While @Primary indicates which bean should be injected by default in case of ambiguity, it doesn’t allow multiple beans with the same name in the same configuration class.
To avoid such conflicts, we need to make sure each method in a configuration class has a unique name. Moreover, we can explicitly specify the name directly in the @Bean annotation using the name attribute:
@Bean(name = "mercedesCar")
public Car car1() {
return new Car("Mercedes");
}
@Bean(name = "bmwCar")
@Primary
public Car car2() {
return new Car("BMW");
}In this case, the beans are named mercedesCar and bmwCar, ensuring uniqueness and avoiding conflicts.
6. Conclusion
In this article, we learned about Spring’s @Primary annotation. With the code examples, we demonstrated the need and the use cases of the @Primary.
The code backing this article is available on GitHub. Once you're logged in as a Baeldung Pro Member, start learning and coding on the project.
