Re: [Jython-users] iterating a Java map

[Jon <jo...@li...>]

Thanks, Santosh. Iterating a Java Map in Java isn't what I'm trying to
figure out, though; it's taking a Java Map object, passing it to Jython, and
iterating using standard Python idioms. If I have a Java Map, I can pass it
from Java to a Jython function using ScriptingEngine.invokeFunction(). The
following works:

def test(mapObj):
  for key in mapObj: # mapObj implements java.util.Map
    print(mapObj[key])

(and this alone undeniably rocks!)


But the following don't work:

def test(mapObj):
  for key, value in mapObj.items(): # items() is not present on mapObj
    print("%s = %s" % (key, value))

def test(mapObj):
  for key, value in mapObj.iteritems(): # iteritems() is not present on
mapObj
    print("%s = %s" % (key, value))


I'm trying to figure out the best way for supporting as much of the standard
Python dictionary methods on a java.util.Map as I can.

Thanks!


Jon

On Fri, Mar 26, 2010 at 2:39 PM, Santosh Tiwari <ti...@gm...> wrote:

> You can iterate a java map in many ways.
>
>
> java.util.Map<Object, Object> hashMap = new ...;
> java.util.Iterator<Object> iter = hashMap.keySet().iterator();
> while(iter.hasNext()) {
>     Object key = iter.next();
>     Object value = hashMap.get(key);
>     //do something with key and object
> }
>
> Template the above code by your type.
>
>
>
>
> On Fri, Mar 26, 2010 at 8:41 AM, Jon <jo...@li...> wrote:
>
>> Hi all,
>>
>> I feel like this question is probably a FAQ, but I haven't been able to
>> turn up any documentation--please point me in the right direction if there's
>> anything relevant.
>>
>> I've got a class in Java that extends java.util.HashMap:
>>
>> class Foo extends HashMap { /* stuff */ }
>>
>> I'm using Jython in an embedded manner to pass instances of Foo to Jython
>> scripts for processing. On the Jython side, I have no trouble indexing into
>> the object, i.e. baz = myFoo['bar'], but a lot of the standard dictionary
>> methods aren't available. I'd like to be able to do this:
>>
>> for k, v in myFoo.items(): # myFoo is from the Java side
>>   if (k == 'bar')
>>     print(v)
>>
>> Specifically, I'd like to be able to use non-modifying dictionary methods,
>> like items(), iteritems(), iterkeys(), itervalues(). How do I get there from
>> here? I'm fine with an 80/20 solution; PyDictionary looks like what I need,
>> except that I do not want the objects stored in the dict to inherit from
>> PyObject (as a rule, the objects I'm storing do have nice Jython
>> conversions). So, I want the class to look like a PyDictionary to the
>> greatest extent possible, but to have its own implementation (which is
>> complex and can't be swapped out).
>>
>> As an aside, what's the difference between PyDictionary and
>> PyDictionaryDerived?
>>
>> Thanks in advance. I've been amazed with how easy it's been to get Jython
>> embedding up and running; it's a huge win for my application.
>>
>>
>> Jon
>>
>>
>>
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>
>
> --
> Santosh Tiwari
> ti...@gm...
>