Re: Trying to Understand Purpose of a Catch Block for IOException in the Presence of One for FileNotFound

Knute Johnson <>
Fri, 12 Aug 2011 08:54:44 -0700
On 8/12/2011 8:39 AM, KevinSimonson wrote:

If I write a piece of code that constructs an object of class
<PrintWriter> by passing it an object of class<BufferedWriter>,
constructed by passing _it_ an object of type<FileWriter> (all three
classes under<>), don't have a<throws> clause, have only a
<catch> clause for<FileNotFoundException>, and then try to compile
the code the compiler complains, telling me, "unreported exception must be caught or declared to
be thrown". Of course, if I put a<catch> clause there for
<IOException>, that fixes the problem and the program compiles just

If, on the other hand, I write a piece of code that constructs an
object of class<Scanner>, constructed by passing it an object of type
<File>, don't have a<throws> clause for<FileNotFoundException>, and
don't put the constructor call in a<try> block at all, I get a
similar complaint about me not saying anything about exception

Finally, if I have some code that has constructors for _both
<PrintWriter> and_<Scanner>, I have to have a<catch> clause for
_both<IOException> and_<FileNotFoundException>, in order to keep the
compiler happy. But in such a situation I have not been able to find
a way to _actually get<IOException> thrown_! What is the purpose of
having a<catch> block for<IOException> if nothing I do with my code
will actually throw an<IOException> that is not a
<FileNotFoundException>? Or, alternately, is there something I can do
to _get_ an<IOException> that is not a<FileNotFoundException>

I would appreciate any information anyone can give me on this.

Kevin Simonson

Show us the actual code.


Knute Johnson

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