Is actively throwing AssertionError in Java good practice? [duplicate]

Answer 1

In my opinion, an AssertionError would be incorrect to use here.

From the docs, an AssertionError extends base class Error

An Error is a subclass of Throwable that indicates serious problems that a reasonable application should not try to catch.

An error should be fatal, whereas I would expect your program to handle this, and display the user a warning message about the unknown operation.

If anything here, I would expect an UnsupportedOperationException to be thrown, and handled elsewhere in the call stack.

Thrown to indicate that the requested operation is not supported.

Consider the case where, not in a calculator, but any code flow that uses ENUMs:

If a developer were to add a new value to an existing enum, I would not expect functions that make use of this existing enum to invoke an error, just because the new value is not supported.