The exception type thrown by a subclass cannot be wider than the exception type thrown by the parent class!

The exception type thrown by a subclass cannot be broader than the type of exception thrown by the parent class.
is to say that overriding the exception thrown by the parent class method can only be the case where the parent class throws a Ioeception exception:
1. To match the exception thrown by the parent class method, throw Ioeception exception
2. The exception thrown is a subclass of the parent class that throws an exception, such as Eofexception exception
3. Do not throw an exception.
4.java.lang.runtimeexception Anomaly or its descendants class exception

throws a broader exception than the parent type in the center of the catch clause. OK.