Bug Resolution: Unable to find main class

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Bug Description

  • IDE: IntelliJ IDEA 2021.3
  • Language: Java
  • Error: Unable to find main class

I have created a multi-module Spring Boot project that will serve as a tool library for other projects to use. When building the multi-module Spring Boot project, the IDE prompts the following error: Unable to find main class.

Solution

The plugin that comes with SpringBoot requires the main method.

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<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
</plugin>

Because this is a utility project, there is no main method, so you need to make the following changes to the parent's pom.xml:

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<plugin>
    <groupId>org.apache.maven.plugins</groupId>			
    <artifactId>maven-compiler-plugin</artifactId>
    <configuration>
        <source>${maven.compiler.source}</source>
        <target>${maven.compiler.target}</target>
        <encoding>${project.build.sourceEncoding}</encoding>
    </configuration>
</plugin>

In a multi-module Springboot project, the child modules' pom.xml will inherit the configuration in the parent's pom.xml.