Java ArrayList in Ruby

Question

When I submit the form to server, Rails.logger.info params gives

{"cgAttr"=>{"1"=>"abc,pqr", "2"=>"US"}}

and I want

{"cgAttr"=>{"1"=>"abc", "1" => "pqr", "2"=>"US"}}

PS. "1" is input text box in UI that take multiple comma-separate values ("abc,pqr") and on server I am converting that entire string into array (["abc", "pqr"]).

Can Any one point me in correct direction?

Basically, I want to create ArrayList similar to Java in my Ruby on Rails application. Does anyone know how to achieve it. (I have not tried JRuby plugin yet)

JRuby is not a "plugin", it is a complete implementation of the Ruby language. — Dave Newton
– Dave Newton, Commented Nov 29, 2011 at 23:42
Ruby hash indexes MUST be unique. You are asking for the hash to have two "1" indexes, which isn't possible. — Carl Zulauf
– Carl Zulauf, Commented Nov 29, 2011 at 23:42

Dave Newton · Accepted Answer · 2011-11-29 23:52:56Z

1

The easiest answer is to use split:

arr = params[:cgAttr]["1"].split(",")

(Also not psyched about using "1" as a parameter name.)

edited Nov 29, 2011 at 23:52

answered Nov 29, 2011 at 23:43

Dave Newton

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10 Comments

Viral Over a year ago

if I do that than it gives "1"=>["abc", "pqr"]. Is there a way I can achieve {"cgAttr"=>{"1"=>"abc", "1" => "pqr", "2"=>"US"}}

Dave Newton Over a year ago

@Viral No, it's a hash. It's not really clear what you're actually trying to do; are you sending something to a Java server? You could use array notation and say { "foo[0]" => "abc", "foo[1]" => "pqr" }. Otherwise you're going to need to be more specific. My code snippet is on the rails side and cannot produce what you're saying, because I'm consuming parameters.

Viral Over a year ago

yeah dave, thanks for guidance..I am actually send values to Java API but the API accept values in this cgAttr = [{name: "abc", loc: "us"}, {name:"pqr", loc:"us"}]. Do you think creating my own hash map will help me?

Dave Newton Over a year ago

@Viral That's a completely different structure; that's an array of hashes. Sure, creating that from the form data would be trivial.

Viral Over a year ago

ok got it...I was trying to explore more options to match that data structure...not sure if I use JRuby that will help me or not.

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bkempner · Accepted Answer · 2011-11-30 00:03:04Z

0

Can't be done, hash key must be a unique value:

{:foo => 'foo1', :foo => 'foo2'} #=> {:foo => 'foo2'}

Think about it, how would you differentiate between the two elements? my_hash[:foo] can only refer to one element, but if two elements have the same :foo key how can you distinguish between the two?

I like Dave Newtons answer, because then you can actually access them, e.g.:

my_hash[:foo][0], my_hash[:foo][1]

answered Nov 30, 2011 at 0:03

bkempner

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1 Comment

Viral Over a year ago

yeah that make more sense...will check any other alternatives

steenslag · Accepted Answer · 2011-11-30 12:15:41Z

0

It can be done:

h = {}
h.compare_by_identity
a = "1"
b = "1"
h[a] = "abc"
h[b] = "pqr"
p h # {"1"=>"abc", "1"=>"pqr"}

but it doesn't feel right.

answered Nov 30, 2011 at 12:15

steenslag

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