[Jython-users] Re: String[][] (was: [Jython-dev] A new FAQ-entry)

[Samuele P. <pe...@in...>]

Hi. (This may be of general interest)

[me on jython-dev answering to Janusch.Waclawczyk ]
> Maybe we should provide better support for this (?).
> 
> [ Janusch Waclawczyk]
> > I wanted to create a new entry to a FAQ, but I failed:
> > 
> > 3.8. How can I create 2-dimen. Java arrays from jython?
> 
> The following works (not that intuitive):
> >>> from java.lang import String,Object
> >>> from jarray import array
> >>> a=array(["a","b"],String)
> >>> a
> array(['a', 'b'], java.lang.String)
> >>> # this is wrong:                             
> >>> b=array([a,a],type(a)) # or a.__class__
> >>> b
> array([array(['a', 'b'], java.lang.String), array(['a', 'b'], 
> java.lang.String)], org.python.core.PyArray)
> >>> # this works !
> >>> b=array([a,a],Object.getClass(a))
> >>> b
> array([array(['a', 'b'], java.lang.String), array(['a', 'b'], 
> java.lang.String)], [Ljava.lang.String;) 
> >>> 
> # [Ljava.lang.String; is the java internal name for (class) type 
> #  java.lang.String[]
> # b is a (jython side) java.lang.String[][]
> 
I forgot to point out, that typically one does not need to work with
java arrays on jython side, lists do the job:

given:

public class Wrap {}

-----

public class Dummmy {

 public static void dummy(Wrap[][] a) {}

}

all this works:
>>> import Dummy
>>> Dummy.dummy([])
>>> Dummy.dummy([[]])
>>> a,b,c,d = [ Wrap() for i in range(0,4) ]
>>> Dummy.dummy([[a,b]])
>>> Dummy.dummy([[a,b],[c,d]])

regards, Samuele Pedroni