SCJP - override method with exception handling raises a compiler error

Question

In the SCJP book by Kathey Sierra, an excerpt is as follows:

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If a method is overridden but you use a polymorphic (supertype) reference to refer to

Answer 1

When you look at the code, you can realize: when the object you invoke eat() on is

• a Dog, then the call will not throw an exception
• an Animal, then that call could throw

Because of that, the second usage results in the compiler complaining to you.

Overriding a method and to reduce the throws signature is perfectly fine. A caller that knows how to deal with an exception for sure works when a sub class never throws.