Partner – Microsoft – NPI EA (tag= Azure)
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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 .

Partner – Codium – NPI EA (site = Main Site)
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Get non-trivial analysis (and trivial, too!) suggested right inside your IDE or Git platform so you can code smart, create more value, and stay confident when you push.

Get CodiumAI for free and become part of a community of over 280,000 developers who are already experiencing improved and quicker coding.

Write code that works the way you meant it to:

CodiumAI. Meaningful Code Tests for Busy Devs

Partner – DBSchema – NPI EA (tag = Spring Data JPA)
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DbSchema is a super-flexible database designer, which can take you from designing the DB with your team all the way to safely deploying the schema .

The way it does all of that is by using a design model , a database-independent image of the schema, which can be shared in a team using GIT and compared or deployed on to any database.

And, of course, it can be heavily visual, allowing you to interact with the database using diagrams, visually compose queries, explore the data, generate random data, import data or build HTML5 database reports.

Take a look at DBSchema

Partner – Aegik AB – NPI EA (cat=JPA)
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Slow MySQL query performance is all too common. Of course it is. A good way to go is, naturally, a dedicated profiler that actually understands the ins and outs of MySQL.

The Jet Profiler was built for MySQL only , so it can do things like real-time query performance, focus on most used tables or most frequent queries, quickly identify performance issues and basically help you optimize your queries.

Critically, it has very minimal impact on your server's performance, with most of the profiling work done separately - so it needs no server changes, agents or separate services.

Basically, you install the desktop application, connect to your MySQL server , hit the record button, and you'll have results within minutes:

out the Profiler

eBook – Guide Junit – NPI EA (cat=Java)
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A quick guide to materially improve your tests with Junit 5:

>> The Junit 5 handbook
eBook – Jackson – NPI EA (cat=Jackson)
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Do JSON right with Jackson

Download the E-book

eBook – HTTP Client – NPI EA (cat=Http Client-Side)
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Get the most out of the Apache HTTP Client

Download the E-book

eBook – Maven – NPI EA (cat = Maven)
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Get Started with Apache Maven:

Download the E-book

eBook – Persistence – NPI EA (cat=Persistence)
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Working on getting your persistence layer right with Spring?

Explore the eBook

eBook – RwS – NPI EA (cat=Spring MVC)
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Building a REST API with Spring?

Download the E-book

Course – RwS – NPI EA (cat=REST)
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Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:

REST With Spring (new)

Course – LS – NPI EA (cat=Spring)
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Get started with Spring and Spring Boot, through the reference Learn Spring course:

>> LEARN SPRING

Partner – Codium – NPI EA (cat = Testing)
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Get non-trivial analysis (and trivial, too!) suggested right inside your IDE or Git platform so you can code smart, create more value, and stay confident when you push.

Get CodiumAI for free and become part of a community of over 280,000 developers who are already experiencing improved and quicker coding.

Write code that works the way you meant it to:

CodiumAI. Meaningful Code Tests for Busy Devs

Partner – Bellsoft – NPI EA (cat = Spring)
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Looking for the ideal Linux distro for running modern Spring apps in the cloud?

Meet Alpaquita Linux : lightweight, secure, and powerful enough to handle heavy workloads.

This distro is specifically designed for running Java apps . It builds upon Alpine and features significant enhancements to excel in high-density container environments while meeting enterprise-grade security standards.

Specifically, the container image size is ~30% smaller than standard options, and it consumes up to 30% less RAM:

Alpaquita Containers now.

Course – LSS – NPI EA (cat=Spring Security)
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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:

>> Learn Spring Security

Partner – DBSchema – NPI EA (tag = SQL)
announcement - icon

DbSchema is a super-flexible database designer, which can take you from designing the DB with your team all the way to safely deploying the schema .

The way it does all of that is by using a design model , a database-independent image of the schema, which can be shared in a team using GIT and compared or deployed on to any database.

And, of course, it can be heavily visual, allowing you to interact with the database using diagrams, visually compose queries, explore the data, generate random data, import data or build HTML5 database reports.

Take a look at DBSchema

Partner – Aegik AB – NPI EA (tag = SQL)
announcement - icon

Slow MySQL query performance is all too common. Of course it is. A good way to go is, naturally, a dedicated profiler that actually understands the ins and outs of MySQL.

The Jet Profiler was built for MySQL only , so it can do things like real-time query performance, focus on most used tables or most frequent queries, quickly identify performance issues and basically help you optimize your queries.

Critically, it has very minimal impact on your server's performance, with most of the profiling work done separately - so it needs no server changes, agents or separate services.

Basically, you install the desktop application, connect to your MySQL server , hit the record button, and you'll have results within minutes:

out the Profiler

Course – LSD – NPI EA (tag=Spring Data JPA)
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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:

>> CHECK OUT THE COURSE

Partner – Bellsoft – NPI (cat = Spring)
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Looking for the ideal Linux distro for running modern Spring apps in the cloud?

Meet Alpaquita Linux : lightweight, secure, and powerful enough to handle heavy workloads.

This distro is specifically designed for running Java apps . It builds upon Alpine and features significant enhancements to excel in high-density container environments while meeting enterprise-grade security standards.

Specifically, the container image size is ~30% smaller than standard options, and it consumes up to 30% less RAM:

Alpaquita Containers now.

1. Overview

Starting with Spring 2.5, the framework introduced annotations-driven Dependency Injection . The main annotation of this feature is @Autowired . It allows Spring to resolve and inject collaborating beans into our bean.

Further reading:

Learn about the mechanism behind Spring component scanning, and how you can tweak it to your own needs
Read more → A quick introduction to the concepts of Inversion of Control and Dependency Injection, followed by a simple demonstration using the Spring Framework
Read more

In this tutorial, we’ll first take a look at how to enable autowiring and the various ways to autowire beans. Afterward, we’ll talk about resolving bean conflicts using @Qualifier annotation, as well as potential exception scenarios.

2. Enabling @Autowired Annotations

The Spring framework enables automatic dependency injection. In other words, by declaring all the bean dependencies in a Spring configuration file, Spring container can autowire relationships between collaborating beans . This is called Spring bean autowiring .

To use Java-based configuration in our application, let’s enable annotation-driven injection to load our Spring configuration:

@Configuration
@ComponentScan("com.baeldung.autowire.sample")
public class AppConfig {}

Alternatively, the <context:annotation-config> annotation is mainly used to activate the dependency injection annotations in Spring XML files.

Moreover, Spring Boot introduces the @SpringBootApplication annotation . This single annotation is equivalent to using @Configuration , @EnableAutoConfiguration , and @ComponentScan .

Let’s use this annotation in the main class of the application:

@SpringBootApplication
public class App {
    public static void main(String[] args) {
        SpringApplication.run(App.class, args);

As a result, when we run this Spring Boot application, it will automatically scan the components in the current package and its sub-packages. Thus it will register them in Spring’s Application Context, and allow us to inject beans using @Autowired.

3. Using @Autowired

After enabling annotation injection, we can use autowiring on properties, setters, and constructors.

3.1. @Autowired on Properties

Let’s see how we can annotate a property using @Autowired. This eliminates the need for getters and setters.

First, let’s define a fooFormatter bean:

@Component("fooFormatter")
public class FooFormatter {
    public String format() {
        return "foo";

Then, we’ll inject this bean into the FooService bean using @Autowired on the field definition:

@Component
public class FooService {  
    @Autowired
    private FooFormatter fooFormatter;

As a result, Spring injects fooFormatter when FooService is created.

3.2. @Autowired on Setters

Now let’s try adding @Autowired annotation on a setter method.

In the following example, the setter method is called with the instance of FooFormatter when FooService is created:

public class FooService {
    private FooFormatter fooFormatter;
    @Autowired
    public void setFormatter(FooFormatter fooFormatter) {
        this.fooFormatter = fooFormatter;

3.3. @Autowired on Constructors

Finally, let’s use @Autowired on a constructor.

We’ll see that an instance of FooFormatter is injected by Spring as an argument to the FooService constructor:

public class FooService {
    private FooFormatter fooFormatter;
    @Autowired
    public FooService(FooFormatter fooFormatter) {
        this.fooFormatter = fooFormatter;

4. @Autowired and Optional Dependencies

When a bean is being constructed, the @Autowired dependencies should be available. Otherwise, if Spring cannot resolve a bean for wiring, it will throw an exception.

Consequently, it prevents the Spring container from launching successfully with an exception of the form:

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: 
No qualifying bean of type [com.autowire.sample.FooDAO] found for dependency: 
expected at least 1 bean which qualifies as autowire candidate for this dependency. 
Dependency annotations: 
{@org.springframework.beans.factory.annotation.Autowired(required=true)}

To fix this, we need to declare a bean of the required type:

public class FooService {
    @Autowired(required = false)
    private FooDAO dataAccessor; 

5. Autowire Disambiguation

By default, Spring resolves @Autowired entries by type. If more than one bean of the same type is available in the container, the framework will throw a fatal exception.

To resolve this conflict, we need to tell Spring explicitly which bean we want to inject.

5.1. Autowiring by @Qualifier

For instance, let’s see how we can use the @Qualifier annotation to indicate the required bean.

First, we’ll define 2 beans of type Formatter:

@Component("fooFormatter")
public class FooFormatter implements Formatter {
    public String format() {
        return "foo";
@Component("barFormatter")
public class BarFormatter implements Formatter {
    public String format() {
        return "bar";

Now let’s try to inject a Formatter bean into the FooService class:

public class FooService {
    @Autowired
    private Formatter formatter;

In our example, there are two concrete implementations of Formatter available for the Spring container. As a result, Spring will throw a NoUniqueBeanDefinitionException exception when constructing the FooService:

Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: 
No qualifying bean of type [com.autowire.sample.Formatter] is defined: 
expected single matching bean but found 2: barFormatter,fooFormatter

We can avoid this by narrowing the implementation using a @Qualifier annotation:

public class FooService {
    @Autowired
    @Qualifier("fooFormatter")
    private Formatter formatter;

When there are multiple beans of the same type, it’s a good idea to use @Qualifier to avoid ambiguity.

Please note that the value of the @Qualifier annotation matches with the name declared in the @Component annotation of our FooFormatter implementation.

5.2. Autowiring by Custom Qualifier

Spring also allows us to create our own custom @Qualifier annotation. To do so, we should provide the @Qualifier annotation with the definition:

@Qualifier
@Target({
  ElementType.FIELD, ElementType.METHOD, ElementType.TYPE, ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
public @interface FormatterType {  
    String value();

Then we can use the FormatterType within various implementations to specify a custom value:

@FormatterType("Foo")
@Component
public class FooFormatter implements Formatter {
    public String format() {
        return "foo";
@FormatterType("Bar")
@Component
public class BarFormatter implements Formatter {
    public String format() {
        return "bar";

Finally, our custom Qualifier annotation is ready to use for autowiring:

@Component
public class FooService {  
    @Autowired
    @FormatterType("Foo")
    private Formatter formatter;

The value specified in the @Target meta-annotation restricts where to apply the qualifier, which in our example is fields, methods, types, and parameters.

5.3. Autowiring by Name

Spring uses the bean’s name as a default qualifier value. It will inspect the container and look for a bean with the exact name as the property to autowire it.

Hence, in our example, Spring matches the fooFormatter property name to the FooFormatter implementation. Therefore, it injects that specific implementation when constructing FooService:

public class FooService {
 @Autowired 
private Formatter fooFormatter; 

6. Conclusion

In this article, we discussed autowiring and the different ways to use it. We also examined ways to solve two common autowiring exceptions caused by either a missing bean or an ambiguous bean injection.

The source code of this article is available on the GitHub project.

Partner – Bellsoft – NPI EA (cat = Spring)
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Looking for the ideal Linux distro for running modern Spring apps in the cloud?

Meet Alpaquita Linux: lightweight, secure, and powerful enough to handle heavy workloads.

This distro is specifically designed for running Java apps. It builds upon Alpine and features significant enhancements to excel in high-density container environments while meeting enterprise-grade security standards.

Specifically, the container image size is ~30% smaller than standard options, and it consumes up to 30% less RAM:

Alpaquita Containers now.

Partner – Bellsoft – NPI EA (cat = Spring)
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Just published a new writeup on how to run a standard Java/Boot application as a Docker container, using the Liberica JDK on top of Alpaquita Linux:

Spring Boot Application on Liberica Runtime Container.

Partner – Aegik AB – NPI EA (tag = SQL)
announcement - icon

Slow MySQL query performance is all too common. Of course it is.

The Jet Profiler was built entirely for MySQL, so it's fine-tuned for it and does advanced everything with relaly minimal impact and no server changes.

out the Profiler

Partner – Codium – NPI EA (cat = Testing)
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Explore the secure, reliable, and high-performance Test Execution Cloud built for scale. Right in your IDE:

CodiumAI. Meaningful Code Tests for Busy Devs

Basically, write code that works the way you meant it to.

Course – LS (cat=Spring)
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Get started with Spring Boot and with core Spring, through the Learn Spring course:

>> CHECK OUT THE COURSE

res – REST with Spring (eBook) (everywhere)
Download the Guide
eBook – Video Security – NPI EA (cat=Spring Security)
access to the video
eBook – Persistence – NPI EA (cat=Persistence)