From: Carlos <angus@...>
Date: 2004-03-31T19:33:07+09:00
Subject: Re: [newbie] Array of Arrays (JRuby raise an exception)

[Yvon Thoraval <yvon.thoravalNO-SPAM@free.fr>, 2004-03-30 10.44 CEST]
> JRuby raise an exception with the following code :

You should give more information if you want help: what exception,
which line, etc.

> 
> columnFields = fieldsHash.keys
> columnHeaders = fieldsHash.values
> selectedFields = fieldsHash.join_keys ", "
> 
> datas = Array.new
> myRows = query.executeQuery("SELECT " + selectedFields + " FROM " + tbl
> + ";")
> while myRows.next()
>         myCols = Array.new
>         fieldsHash.keys.each {|fhk| myCols << myRows.getString(fhk)}

If fieldsHash is a normal ruby Hash, the order of the keys is
arbitrary.

[...]

> i suspect de line :
> 
> datas << myCols flatten the Array "datas" which has to be an Array of
> Arrays that's to say each element of the Array "datas" has to be an
> Array itself (being a set of columns from a database)
> 
> the equivalent in Java/BeanShell being Vector of Vectors.
> 
> i'm sure (print out) all datas are OK but the structure of them.
> 
> then the question is to know if the line "datas << myCols" returns an
> Array of Array or simply an concataneted Array ???

To see what is in a variable, use 'p' or #inspect. 'p' prints,
#inspect returns a string.

$ ruby -e 'a=["1",2,["3"]]; p a; puts a.inspect'
["1", 2, ["3"]]
["1", 2, ["3"]]

Good luck.