Creating Custom Exceptions in Java

Quick Answer

Calling super(cause) inside a custom exception's constructor is correct because that call forwards the cause straight to Throwable's own constructor, and Throwable is built specifically to store whatever cause it is given and expose it later through getCause(), so you do not need to write any additional code to wire that up yourself. This is the mechanism that underlies exception chaining: instead of only reporting that something failed, your custom exception can preserve the original lower-level exception that triggered it, so anyone debugging later can trace the full cause-and-effect chain rather than seeing just the outermost symptom. It is also why the best practice of giving custom exceptions a constructor that accepts both a message and a cause matters so much: the message lets you describe what went wrong in terms meaningful to your application, while the cause preserves the underlying technical failure for logging and debugging, and calling super with the cause is what actually connects your custom exception into that chain rather than just extending Throwable in name only. On the exam, whenever a question centers on custom exceptions and mentions passing a cause into a super constructor call, recognize that the heavy lifting is already handled by Throwable itself; your job as the subclass author is simply to call the right super constructor and expose sensible constructors to callers.