Enthuware

mehtapra wrote:In option 3 it says this statement is valid:

class CleanConnector extends PortConnector {    public CleanConnector(int port) throws IOException, FileNotFoundException, SomeOtherCheckedException {          super(port);    } }


I am not sure if throwing 'FileNotFoundException' is valid....as in another explanation in the same question it says:

'An overriding method cannot throw a superclass exception, while a constructor of a subclass cannot throw subclass exception.'

Can you please clarify on this?

Thanks

As PortConnector has only one constructor, ...

...other valid code.

convertor wrote: ...
our previous code where we catch IOException and met suddenly Exception, will not work.

An overriding method cannot throw a superclass exception

while a constructor of a subclass cannot throw subclass exception...

class A{
     public A() throws IOException{ }
     void m() throws IOException{ }   
}    

class B extends A{
     //Exception is valid here, but FileNotFoundException is invalid
     public B() throws Exception{ }

      //FileNotFoundException is valid here, but Exception is invalid
     void m() throws FileNotFoundException{ } 
}

It is not possible to define CleanConnector that does not throw IOException at instantiation.

It is not possible to define CleanConnector that throws IOException at instantiation.

OCAJO1 wrote: ↑

Thu Dec 13, 2018 8:33 pm

The reason that the constructor of a subclass must throw a superclass (not subclass) of the exception that superclass' constructor throws, is it a Java agreed upon convention or there is actually a logic flow behind it?

OCAJO1 wrote: ↑

Sun Dec 16, 2018 4:23 pm

It cares because when the subclass' constructor calls the superclass' constructor (not withstanding the case in Note) the superclass' constructor has to have the same or higher class of exception compare to the subclass' constructor.