How do I tell Spring Boot which main class to use for the executable jar?

How to Choose the Right Main Class for Your Spring Boot Executable JAR

📝🚀 Welcome back, tech enthusiasts! Have you ever faced the issue of having multiple classes with a main method in your Spring Boot project? And later, encountered this error when trying to build an executable JAR using the Spring Boot Maven plugin?

Execution default of goal org.springframework.boot:spring-boot-maven-plugin:1.0.1.RELEASE:repackage failed: Unable to find a single main class from the following candidates

🤔 No worries, my tech-savvy friend! In this blog post, I'll guide you through the process of specifying the main class for your Spring Boot executable JAR, so let's dive in! 💡🚀

Understanding the Problem

When you have multiple classes with main methods, Spring Boot's Maven plugin cannot automatically determine which class to use as the entry point for your executable JAR. As a result, it throws an error, making it impossible to build the JAR file.

The Solution: Specifying the Main Class

To solve this problem, you need to explicitly define the main class for the Maven plugin to use. There are two approaches you can take depending on your project setup:

Approach 1: Using Maven Properties

1️⃣ Open your project's pom.xml file.

2️⃣ Inside the properties section, add the following line:

<spring.boot.mainclass>com.yourpackage.YourMainClass</spring.boot.mainclass>

ℹ️ Replace com.yourpackage.YourMainClass with the fully qualified name of your desired main class.

3️⃣ Save the pom.xml file.

Approach 2: Using the Maven Plugin Configuration

If you prefer a configuration-based approach, you can add the following lines inside the plugins section of your pom.xml file:

<plugin>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-maven-plugin</artifactId>
  <configuration>
    <mainClass>com.yourpackage.YourMainClass</mainClass>
  </configuration>
</plugin>

ℹ️ Replace com.yourpackage.YourMainClass with the fully qualified name of your desired main class.

✨ Now, when you build your Spring Boot project as an executable JAR, the Maven plugin will use the specified main class as the entry point.

📢 Call-to-Action: Share Your Experience!

🎉 Congratulations! You now know how to tell Spring Boot which main class to use for the executable JAR. Give it a try and see how it works for you!

If you found this blog post helpful, make sure to hit that share button and spread the knowledge with your fellow tech enthusiasts. And don't forget to leave a comment below sharing your success story or any additional questions you might have. Let's keep the discussion going! 🤗💡

That's all for now, folks! Stay tuned for more tech tutorials and helpful tips from our blog. Until then, happy coding! 🚀✨