Sealed classes, introduced in Java 15, provide a mechanism for controlling class hierarchies by explicitly specifying which classes are permitted to extend them, thus enhancing code predictability and reducing unintended extensions. This feature is particularly valuable in managing complex class hierarchies by preventing unauthorized subclassing, thereby minimizing potential errors and bugs in the codebase. The use of the sealed modifier, alongside the permits keyword, ensures compile-time error detection when unauthorized subclasses are attempted, improving code readability and refactoring safety. Sealed classes are also beneficial for API stability, as they allow library developers to control which parts of the API can be extended by client code, preventing breaking changes in future releases. The overall aim is to improve code quality by providing clear boundaries within class hierarchies, offering developers increased confidence when working with Java applications. Additionally, tools like Rollbar can be employed for real-time error tracking and management, further aiding in maintaining robust and reliable Java code.