In what cases is it more convenient to use Java configuration, and in what cases XML configuration?

Using Java configuration is more convenient in cases:

• Complex logic for creating and wiring beans, requiring a programmatic approach.
• Configuration depends on external conditions of the application runtime.
• Preference for type safety and refactoring capabilities provided by Java IDE.
• Integration with existing Java code, where it makes sense to define configuration nearby.

Using XML configuration is more convenient in cases:

• Simple configuration, where only bean declarations and dependencies are needed.
• Separation of configuration from application code, which can be useful for administration.
• Historically established practice in the project.

In most modern Spring applications, Java configuration is preferred as a more flexible and type-safe approach. However, for simple cases or for backward compatibility, XML remains relevant.