Reliability - Java Coding Guidelines - page 165

occur.Finally,thiscodedemonstrateshowtoaccesseveryexceptionthatmaybeproduced
from the try -with-resources block.
If only one exception is thrown, during opening, processing, or closing of the files, the
exception will be printed after "thrown exception:" . If an exception is thrown during
processing, and a second exception is thrown while trying to close either file, the second
exception will be printed after "thrown exception:" , and the first exception will be
printed after "suppressed exception:" .
Applicability
Failing to correctly handle all failure cases when working with closeable resources may
result in some resources not being closed or in important exceptions being masked, pos-
sibly resulting in a denial of service. Note that failure to use a try -with-resources state-
ment cannot be considered a security vulnerability in and of itself , because it is possible
to write a correctly structured group of nested try - catch - finally blocks guarding the
resources that are in use (see “ ERR05-J. Do not let checked exceptions escape from a fi-
nally block ” [Long 2012]). That said, failure to correctly handle such error cases is a
commonsourceofvulnerabilities.Useofa try -with-resourcesstatementmitigatesthisis-
suebyguaranteeingthattheresourcesaremanagedcorrectlyandthatexceptionsarenever
masked.
Bibliography
[JLS 2013]
§14.20.3, “ try -with-resources”
[Long 2012]
ERR05-J. Do not let checked exceptions escape from a finally block
FIO03-J. Remove temporary files before termination
FIO04-J. Close resources when they are no longer needed
[Tutorials 2013]
The try -with-resources Statement