Java Learning Knowledge Points Summary

Exception handling

1. In exception handling, if a subclass overrides a method of the parent class, the checked exception declared in the subclass method cannot be more general than the exception declared by the parent class method, that is, the subclass method can throw a more specific exception ( no more than the exception range declared by the parent class method). That is, the parent class method declares the child exception derived by the exception ), or does not throw any exceptions. Also, if the parent class method does not throw an exception, the subclass cannot throw any checked exceptions.

Personal understanding: Because object-oriented has polymorphic characteristics, that is, the parent class can refer to the child class object, through the parent class to access the subclass method to achieve polymorphism (rewrite). In this call chain, the subclass method cannot throw an exception that the parent class method cannot accept, that is, the exception declared by the parent class should be more general.

Java Learning Knowledge Points Summary