[jira] Commented: (LANG-576) Add methods for cloneables to ObjectUtils

["Oliver Heger (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LANG-576?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12794483#action_12794483 ] 

Oliver Heger commented on LANG-576:
-----------------------------------

I would like to see support for cloning in lang, too. LANG-307 suggests a {{CloneUtils}} class. {{CloneUtils}} also provides a method that tries to invoke {{clone()}} through reflection. So I think LANG-307 is a super set of this proposal. Maybe the implementations in these proposals can be merged?

> 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: 3.0
>
>         Attachments: Cloneable.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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