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From "Joerg Schaible (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LANG-576) Add methods for cloneables to ObjectUtils
Date Mon, 08 Feb 2010 23:13:27 GMT

    [ https://issues.apache.org/jira/browse/LANG-576?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12831185#action_12831185
] 

Joerg Schaible commented on LANG-576:
-------------------------------------

Looking at the comments of LANG-307 I am with Paul. This clone functionality is simple and
basic enough (relies completely on the JDK definition of the Cloenable) to be part of ObjectUtils.
The clone functionality in CloneUtils tries to do a lot smarter things. Therefore I'd like
to commit this for 3.0 if nobody objects.
When we add CloneUtils later, we can either delegate from ObjectUtils to CloneUtils.cloneByReflection
or vice versa.

> Add methods for cloneables to ObjectUtils
> -----------------------------------------
>
>                 Key: LANG-576
>                 URL: https://issues.apache.org/jira/browse/LANG-576
>             Project: Commons Lang
>          Issue Type: New Feature
>          Components: lang.*
>            Reporter: Joerg Schaible
>            Assignee: Joerg Schaible
>            Priority: Minor
>             Fix For: 3.1
>
>         Attachments: Cloneable.diff, CloneableTest.diff
>
>
> Object.clone is declared protected, which makes it impossible to write code like:
> {code:java}
> if (obj instanceof Cloneable) {
>   Object clone = obj.clone();
>   ...
> }
> {code}
> Following two methods will help in such a situation:
> {code:java}
>     /**
>      * Clone an object.
>      * 
>      * @param <T> the type of the object
>      * @param o the object to clone
>      * @return the clone if the object implements {@link Cloneable} otherwise <code>null</code>
>      * @throws CloneFailedException if the object is cloneable and the clone operation
fails
>      * @since 3.0
>      */
>     public static <T> T clone(final T o) {
>         if (o instanceof Cloneable) {
>             try {
>                 final Method clone = o.getClass().getMethod("clone", (Class[])null);
>                 @SuppressWarnings("unchecked")
>                 final T result = (T)clone.invoke(o, (Object[])null);
>                 return result;
>             } catch (final NoSuchMethodException e) {
>                 throw new CloneFailedException("Cloneable type has no clone method",
e);
>             } catch (final IllegalAccessException e) {
>                 throw new CloneFailedException("Cannot clone Cloneable type", e);
>             } catch (final InvocationTargetException e) {
>                 throw new CloneFailedException("Exception cloning Cloneable type", e.getCause());
>             }
>         }
>         return null;
>     }
>     /**
>      * Clone an object if possible.
>      * 
>      * @param <T> the type of the object
>      * @param o the object to clone
>      * @return the clone if the object implements {@link Cloneable} otherwise the object
itself
>      * @throws CloneFailedException if the object is cloneable and the clone operation
fails
>      * @since 3.0
>      */
>     public static <T> T cloneIfPossible(final T o) {
>         final T clone = clone(o);
>         return clone == null ? o : clone;
>     }
> {code}
> Comments? Note, that the code currently introduces also a new CloneFailedException. Use
another existing one?
> Unit tests will be provided also.

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