NullPointerException, Map and values().iterator()

[umk]

I'm trying to figure this one out:

Person person = new Person();
person.setHobbies(new HashMap());
Iterator i = person.getHobbies().values().iterator();

Util.getClusterCache().putObject("/test", person);
person = (Person)Util.getClusterCache().getObject("/test");

i = person.getHobbies().values().iterator();
...
public static synchronized TreeCacheAop getClusterCache(){
 if(treeCache == null){
 try {
 treeCache = new TreeCacheAop();
 PropertyConfigurator config = new PropertyConfigurator(); // configure tree cache.
 config.configure(treeCache, "META-INF/replSync-service.xml");
 treeCache.startService();
 } catch (Exception e) {
 traceLog.fatal("Error while initializing JBoss cache", e);
 }
 }
 return treeCache;
}

Why does line 8 (.values.iterator()) cause a NullPointerException but line 3 doesn't?

[ben.wang]

I am surprised that line doesn't cause NPE either. Keep in mind that TreeCacheAop only supports limited Collection classes API. And values() is not currently supported!

I am working on to provide a more complete set of API to support though. It's planned to come out in post-1.1.

So stay tuned.

-Ben

[umk]

Thanks for the info. Where can I find a list of what API TreeCacheAop supports and what it doesn't?

[ben.wang]

I don't have it except in the source code. But please bear with me. Once I have the Collection class API re-implemented in 1.x, I will document it.

Thanks,

-Ben