Issue1146

C:\jython2.5a3>jython
Jython 2.5a3 (trunk:5315:5317, Sep 10 2008, 20:54:23)
[Java HotSpot(TM) Client VM (Sun Microsystems Inc.)] on java1.6.0_07
Type "help", "copyright", "credits" or "license" for more information.
>>> import java
>>>
>>> x=java.util.Hashtable()
>>> x.put('test', 1)
>>> x
{test=1}
>>> dict(x)
{'test': 1}
>>>
>>> x=java.util.HashMap()
>>> x.put('test', 1)
>>> x
{test=1}
>>> dict(x)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: dictionary update sequence element #0 has length 4; 2 is 
required
>>>

I think behavior of dict() with java.util.HashMap is wrong.

The problem was that PyDictionary was checking if the argument it was
passed had a 'keys' method and then calling it and iterating them. 
Hashtable has a keys method, but HashMap and the Map interface have a
'keySet' method.  If a keys method doesn't exist, PyDictionary iterates
the argument for key-value pairs.  However, iterating HashMap produces
the keys, not the key-value pairs.  Since strings in python are iterable
and support __len__, PyDictionary was complaining that it wasn't the
right length, ie a pair.

I've attached a patch to check if the object supports the keySet method,
and use that instead of the keys method.  I also added a bugtest.

To be fixed by the RC

Fixed by r6106