Structuring code and the main application class

Spring Boot imposes no specific code layout requirements, but adhering to best practices aids development. Avoid the default package, as it causes issues with @ComponentScan, @ConfigurationPropertiesScan, @EntityScan, and @SpringBootApplication by reading every class from every jar. Instead, follow Java’s recommended naming conventions using a reversed domain name, such as com.example.project. Place the main application class in a root package above other classes to define a base search package for items like JPA @Entity classes. This structure ensures component scan applies only to the project. While @SpringBootApplication is typically used on the main class, @EnableAutoConfiguration and @ComponentScan can be used instead. For domain-based structures, consider Spring Modulith. The recommended layout groups classes under the root package, with the main class containing the main method and @SpringBootApplication annotation. Scope: Spring Boot. Reviewed October 4, 2026.