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Partner – Microsoft – NPI EA (cat = Baeldung)
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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, visit the documentation page.

You can also ask questions and leave feedback on the Azure Container Apps GitHub page.

Partner – Microsoft – NPI EA (cat= Spring Boot)
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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 – Orkes – NPI EA (cat=Spring)
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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.

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Partner – Orkes – NPI EA (tag=Microservices)
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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.

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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.

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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.

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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:

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Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:

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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:

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Course – All Access – NPI EA (cat= Spring)
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Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.

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Partner – LambdaTest – NPI EA (cat=Testing)
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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:

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1. Overview

A common practice in Spring Boot is using an external configuration to define our properties. This allows us to use the same application code in different environments.

We can use properties files, YAML files, environment variables and command-line arguments.

In this short tutorial, we’ll explore the main differences between properties and YAML files.

2. Properties Configuration

By default, Spring Boot can access configurations set in an application.properties file, which uses a key-value format:

spring.datasource.url=jdbc:h2:dev
spring.datasource.username=SA
spring.datasource.password=password

Here each line is a single configuration, so we need to express hierarchical data by using the same prefixes for our keys. And in this example, every key belongs to spring.datasource.

2.1. Placeholders in Properties

Within our values, we can use placeholders with the ${} syntax to refer to the contents of other keys, system properties, or environment variables:

app.name=MyApp
app.description=${app.name} is a Spring Boot application

2.2. List Structure

If we have the same kind of properties with different values, we can represent the list structure with array indices:

application.servers[0].ip=127.0.0.1
application.servers[0].path=/path1
application.servers[1].ip=127.0.0.2
application.servers[1].path=/path2
application.servers[2].ip=127.0.0.3
application.servers[2].path=/path3

2.3. Multiple Profiles

Since version 2.4.0, Spring Boot supports creating multi-document properties files. Simply put, we can split a single physical file into multiple logical documents.

This allows us to define a document for each profile we need to declare, all in the same file:

logging.file.name=myapplication.log
bael.property=defaultValue
#---
spring.config.activate.on-profile=dev
spring.datasource.password=password
spring.datasource.url=jdbc:h2:dev
spring.datasource.username=SA
bael.property=devValue
#---
spring.config.activate.on-profile=prod
spring.datasource.password=password
spring.datasource.url=jdbc:h2:prod
spring.datasource.username=prodUser
bael.property=prodValue

Note we use the ‘#&#45&#45&#45’ notation to indicate where we want to split the document.

In this example, we have two spring sections with different profiles tagged. Also, we can have a common set of properties at the root level — in this case, the logging.file.name property will be the same in all profiles.

2.4. Profiles Across Multiple Files

As an alternative to having different profiles in the same file, we can store multiple profiles across different files. Prior to version 2.4.0, this was the only method available for properties files.

We achieve this by putting the name of the profile in the file name — for example, application-dev.yml or application-dev.properties.

3. YAML Configuration

3.1. YAML Format

As well as Java properties files, we can also use YAML-based configuration files in our Spring Boot application. YAML is a convenient format for specifying hierarchical configuration data.

Now let’s take the same example from our properties file and convert it to YAML:

spring:
    datasource:
        password: password
        url: jdbc:h2:dev
        username: SA

This can be more readable than its property file alternative since it does not contain repeated prefixes.

3.2. List Structure

YAML has a more concise format for expressing lists:

application:
    servers:
    -   ip: '127.0.0.1'
        path: '/path1'
    -   ip: '127.0.0.2'
        path: '/path2'
    -   ip: '127.0.0.3'
        path: '/path3'

3.3. Multiple Profiles

Unlike properties files, YAML supports multi-document files by design, and this way, we can store multiple profiles in the same file no matter which version of Spring Boot we use.

In this case, however, the spec indicates we have to use three dashes to indicate the start of a new document:

logging:
  file:
    name: myapplication.log
---
spring:
  config:
    activate:
      on-profile: staging
  datasource:
    password: 'password'
    url: jdbc:h2:staging
    username: SA
bael:
  property: stagingValue

Note: We usually don’t want to include both the standard application.properties and the application.yml files in our project at the same time, as it could lead to unexpected results.

For instance, if we combine the properties shown above (in an application.yml file) with the properties described in Section 2.3., then bael.property would be assigned with defaultValue instead of with the profile-specific value. This is simply because the application.properties are loaded later on, overriding the values assigned up to that point.

4. Spring Boot Usage

Now that we’ve defined our configurations, let’s see how to access them.

4.1. Value Annotation

We can inject the values of our properties using the @Value annotation:

@Value("${key.something}")
private String injectedProperty;

Here the property key.something is injected via field injection into one of our objects.

4.2. Environment Abstraction

We can also obtain the value of a property using the Environment API:

@Autowired
private Environment env;

public String getSomeKey(){
    return env.getProperty("key.something");
}

4.3. ConfigurationProperties Annotation

Finally, we can also use the @ConfigurationProperties annotation to bind our properties to type-safe structured objects:

@ConfigurationProperties(prefix = "mail")
public class ConfigProperties {
    String name;
    String description;
...

5. Conclusion

In this article, we’ve seen some differences between properties and yml Spring Boot configuration files. We also saw how their values could refer to other properties. Finally, we looked at how to inject the values into our runtime.

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.
Baeldung Pro – NPI EA (cat = Baeldung)
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Baeldung Pro comes with both absolutely No-Ads as well as finally with Dark Mode, for a clean learning experience:

>> Explore a clean Baeldung

Once the early-adopter seats are all used, the price will go up and stay at $33/year.

Partner – Microsoft – NPI EA (cat = Spring Boot)
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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, visit the documentation page.

You can also ask questions and leave feedback on the Azure Container Apps GitHub page.

Partner – Orkes – NPI EA (cat = Spring)
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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.

Partner – Orkes – NPI EA (tag = Microservices)
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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.

eBook – HTTP Client – NPI EA (cat=HTTP Client-Side)
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The Apache HTTP Client is a very robust library, suitable for both simple and advanced use cases when testing HTTP endpoints. Check out our guide covering basic request and response handling, as well as security, cookies, timeouts, and more:

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eBook – Java Concurrency – NPI EA (cat=Java Concurrency)
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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:

>> Download the eBook

eBook – Java Streams – NPI EA (cat=Java Streams)
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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:

>> Join Pro and download the eBook

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

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Course – LS – NPI EA (cat=REST)

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Get started with Spring Boot and with core Spring, through the Learn Spring course:

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Course – Spring Sale 2025 – NPI EA (cat= Baeldung)
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Partner – Microsoft – NPI (cat=Spring)
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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, visit the documentation page.

You can also ask questions and leave feedback on the Azure Container Apps GitHub page.

eBook Jackson – NPI EA – 3 (cat = Jackson)
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