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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-5840) Clean up compiler warnings introduced by using Java 5 language features
Date Mon, 16 Jul 2012 09:27:34 GMT

     [ https://issues.apache.org/jira/browse/DERBY-5840?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Knut Anders Hatlen updated DERBY-5840:

    Attachment: derby-5840-05-aa-client-deprecation.diff

I mentioned that I had tried to change the source level for the network client and found that
it caused a lot of deprecation warnings to pop up, even though the methods were deprecated
before Java 5. I found an explanation in this bug report: http://bugs.sun.com/view_bug.do?bug_id=6394563

The compile target in java/client/build.xml specifies nowarn="on", which is supposed to silence
warnings. However, it only silences non-mandatory warnings, and deprecation warnings became
mandatory in Java 5. So when source level changes from 1.4 to 1.5, the compiler isn't allow
to ignore the deprecation warnings.

The attached patches change the source and target level for the network client code to 1.5,
and clean up the warnings. I've split this change in two separate patches so that it's easier
to see which changes are for generics/unchecked conversion warnings, and which changes are
for the deprecation warnings.

derby-5840-04-aa-client-level.diff changes the compiler level and addresses the unchecked
conversion warnings by using generics in signatures.

One thing to note is that it removes the getTypeMap() implementations in LogicalConnection40
and NetConnection40, as the getTypeMap() implementations in their respective super-classes
now have the correct generic signature and no overrides are needed anymore.

derby-5840-05-aa-client-deprecation.diff cleans up the deprecation warnings. There were three
kinds of warnings:

- Use of deprecated class java.io.StringBufferInputStream in Clob, ClobOutputStream and ClobWriter.
This code is only used when accessing clobs on an old server that doesn't support locators,
so I just silenced them using a @SuppressWarnings("deprecation") annotation for now. I did
however refactor the code so that the annotation only had to be added at one isolated location.

- LogicalCallableStatement and LogicalPreparedStatement implement some deprecated methods
(which they have to implement in order to satisfy the interface), and the compiler complains
because they are implemented by forwarding the calls to deprecated methods in the physical
statement classes. Adding @Deprecated annotations to the methods in the logical statement
classes silences the warnings, as calling deprecated methods from other deprecated methods
does not cause warnings.

- The ResultSet class uses deprecated methods in java.util.Date. The patch makes it use non-deprecated
methods in java.util.Calendar instead.

The regression tests ran cleanly with these patches, and the compiler didn't emit any warnings.
> Clean up compiler warnings introduced by using Java 5 language features
> -----------------------------------------------------------------------
>                 Key: DERBY-5840
>                 URL: https://issues.apache.org/jira/browse/DERBY-5840
>             Project: Derby
>          Issue Type: Improvement
>          Components: Miscellaneous
>    Affects Versions:
>            Reporter: Rick Hillegas
>         Attachments: derby-5840-01-aa-compatibilityTests.diff, derby-5840-02-aa-compatibilityTests-again.diff.txt,
derby-5840-03-aa-drda.diff, derby-5840-03-ab-drda.diff, derby-5840-04-aa-client-level.diff,
> Using Java 5 language features forces us to compile code at level 5 or higher. At this
level, the compiler raises warnings not seen at lower levels. This issue is a place to discuss
and attach cleanup to eliminate these warnings.

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