Rare NPE in Sun14ReflectionProvider

• JDK version and platform:

  Sun 1.4.2_17 for Windows

Under unfavorable circumstances method getMungedConstructor in Sun14ReflectionProvider class might return null, what leads to NullPointerException in method newInstance. It occurs when GC has cleared the WeakReference. See stack trace below:

...
Caused by: java.lang.NullPointerException
at com.thoughtworks.xstream.converters.reflection.Sun14ReflectionProvider.newInstance(Sun14ReflectionProvider.java:74)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.instantiateNewInstance(AbstractReflectionConverter.java:2
79)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:149)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:81)
... 49 more

This happens as well with current SVN release (rev 1488)

Proposed fix:

private Constructor getMungedConstructor(Class type) throws NoSuchMethodException {
final WeakReference ref = (WeakReference)constructorCache.get(type);
Constructor ctor = null;
if(ref != null) { ctor = (Constructor) ref.get(); }
if (ctor == null) { ctor = reflectionFactory.newConstructorForSerialization(type, Object.class.getDeclaredConstructor(new Class[0])); constructorCache.put(type, new WeakReference(ctor)); }
return ctor;
}