[LANG-576] Add methods for cloneables to ObjectUtils

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.0
• Component/s: lang.*
• Assignee: Joerg Schaible
• Reporter: Joerg Schaible
• Created: 23/Dec/09 15:49
• Updated: 28/Mar/10 18:18
• Resolved: 28/Mar/10 18:18

Description

Object.clone is declared protected, which makes it impossible to write code like:

if (obj instanceof Cloneable) {
  Object clone = obj.clone();
  ...
}

Following two methods will help in such a situation:

    /**
     * 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;
    }

Comments? Note, that the code currently introduces also a new CloneFailedException. Use another existing one?

Unit tests will be provided also.

Issue Links

• is related to: LANG-307 CloneUtils - utility class to enable cloning via various different mechanisms