Cached collections don't handle null values correctly ----------------------------------------------------- Key: JBCACHE-398 URL: https://issues.jboss.org/browse/JBCACHE-398 Project: JBoss Cache Issue Type: Bug Security Level: Public(Everyone can see) Components: Legacy POJO Cache Affects Versions: 1.2.4SP1 Reporter: twundke Assignee: Scott Marlow Fix For: 1.3.0.GA When a null value is placed into a cached collection (CachedListImpl etc), the node for that element is removed from the cache. This is because TreeCacheAopDelegate._putObject() calls _removeObject() when provided with a null value. This behaviour breaks size() in the case where a collection allows null values to be stored (ArrayList, HashMap etc). The cache needs to explicitly store a null object (eg. org.jboss.util.Null) so that collections work as expected. I have a fix, which basically involves calling the following methods in the correct places: private Object toNullObject( Object aObject ) { if ( aObject == null ) { return Null.VALUE; } // if else { return aObject; } // else } // toNullObject private Object toNullValue( Object aObject ) { if ( Null.VALUE.equals( aObject ) ) { return null; } // if else { return aObject; } // else } // toNullObject So, for example, we can use: public Object get() { ... return toNullValue(cache_.getObject(...)); } These methods should be placed in a common area to be called by each collection class. In addition to this, the CachedListImpl.checkArgument(Object) method should be removed.