[collections] The target Java version for 4.5

[Efremov, Rodion]

Hello,

What Java version Collections 4.5 is being built for?

Best regards,

Re: [collections] How about a HashBidiMap?

[Efremov, Rodion]

Having taking a closer look the way DualHashBidiMap and Java's HashMap are 
implemented, my implementation has only two advantages:


(1) It maintains an additional list of entries. This allows faster iteration 
since it does not have to visit empty collision chain buckets. Also, it allows 
faster relinking of the mapping objects when making the hash tables larger. (I 
believe this may be alleviated by using LinkedHashMaps in DualHashBidiMap 
instead of HashMaps.)


(2) Collision "chains" are actually collision (AVL) trees; this allows worst 
case logarithmic modification/access in case the hash function is poor.


What would your opinion on the above arrangements?


Best regards,

Rodion




From: Javen O'Neal 
Sent: Thursday, July 6, 2017 1:11:23 PM
To: Commons Developers List
Subject: Re: [collections] How about a HashBidiMap?

It wasn't a rhetorical question. I wanted to open discussion on your
contribution, and wanted to start with what folks on this mailing list are
most familiar with.

I'm not a Commons Collection maintainer, but I'm curious if you could
describe your implementation in a few sentences and how it differs from the
current DualHashBidiMap implementation. Is it faster than other
implementations? Does it have a lower memory footprint by sharing key and
value objects between two underlying HashMaps? Does it implement its own
HashMap interface implementing its own Map data structure?

Can you name one or two scenarios where your implementation would be
preferred over the existing implementations?

On Jul 6, 2017 11:56, "Efremov, Rodion"  wrote:

> From
> http://svn.apache.org/viewvc/commons/proper/collections/
> trunk/src/main/java/org/apache/commons/collections4/
> bidimap/DualHashBidiMap.java?view=markup
>
> "Commons Collections would welcome the addition of a direct hash-based
> implementation of the BidiMap interface"
>
> Guess I was wrong.
>
> 
> From: Javen O'Neal 
> Sent: Thursday, July 6, 2017 12:51:25 PM
> To: Commons Developers List
> Subject: Re: [collections] How about a HashBidiMap?
>
> How is this different from the existing DualHashBidiMap?
>
> https://commons.apache.org/proper/commons-collections/
> javadocs/api-release/org/apache/commons/collections4/
> bidimap/DualHashBidiMap.html
>
> On Jul 6, 2017 09:06, "Efremov, Rodion" 
> wrote:
>
> > Hello,
> >
> >
> > I am working on a hash table based BidiMap at
> > https://github.com/coderodde/BidirectionalHashMap/blob/
> > master/src/net/coderodde/util/BidirectionalHashMap.java
> >
> > and would like to contribute it to Commons Collections. Could someone
> > working on the project discuss my contribution attempt?
> >
> >
> > Best regards,
> >
> > Rodion
> >
> > [https://avatars2.githubusercontent.com/u/1770505?v=3&s=400] > github.com/coderodde/BidirectionalHashMap/blob/
> > master/src/net/coderodde/util/BidirectionalHashMap.java>
> >
> > coderodde/BidirectionalHashMap<https://github.com/coderodde/
> > BidirectionalHashMap/blob/master/src/net/coderodde/util/
> > BidirectionalHashMap.java>
> > github.com
> > BidirectionalHashMap - My implementation of a bidirectional bijective
> hash
> > map in Java
> >
> >
> >
>

Re: [collections] How about a HashBidiMap?

[Efremov, Rodion]

From
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/main/java/org/apache/commons/collections4/bidimap/DualHashBidiMap.java?view=markup

"Commons Collections would welcome the addition of a direct hash-based 
implementation of the BidiMap interface"

Guess I was wrong.


From: Javen O'Neal 
Sent: Thursday, July 6, 2017 12:51:25 PM
To: Commons Developers List
Subject: Re: [collections] How about a HashBidiMap?

How is this different from the existing DualHashBidiMap?

https://commons.apache.org/proper/commons-collections/javadocs/api-release/org/apache/commons/collections4/bidimap/DualHashBidiMap.html

On Jul 6, 2017 09:06, "Efremov, Rodion"  wrote:

> Hello,
>
>
> I am working on a hash table based BidiMap at
> https://github.com/coderodde/BidirectionalHashMap/blob/
> master/src/net/coderodde/util/BidirectionalHashMap.java
>
> and would like to contribute it to Commons Collections. Could someone
> working on the project discuss my contribution attempt?
>
>
> Best regards,
>
> Rodion
>
> [https://avatars2.githubusercontent.com/u/1770505?v=3&s=400] github.com/coderodde/BidirectionalHashMap/blob/
> master/src/net/coderodde/util/BidirectionalHashMap.java>
>
> coderodde/BidirectionalHashMap<https://github.com/coderodde/
> BidirectionalHashMap/blob/master/src/net/coderodde/util/
> BidirectionalHashMap.java>
> github.com
> BidirectionalHashMap - My implementation of a bidirectional bijective hash
> map in Java
>
>
>

[collections] How about a HashBidiMap?

[Efremov, Rodion]

Hello,


I am working on a hash table based BidiMap at 
https://github.com/coderodde/BidirectionalHashMap/blob/master/src/net/coderodde/util/BidirectionalHashMap.java

and would like to contribute it to Commons Collections. Could someone working 
on the project discuss my contribution attempt?


Best regards,

Rodion

[https://avatars2.githubusercontent.com/u/1770505?v=3&s=400]

coderodde/BidirectionalHashMap
github.com
BidirectionalHashMap - My implementation of a bidirectional bijective hash map 
in Java

[collections]

[Efremov, Rodion]

Good day!


I am working on a bidirectional (bijective) hash map at 
https://github.com/coderodde/BidirectionalHashMap


In 
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/main/java/org/apache/commons/collections4/bidimap/DualHashBidiMap.java?view=markup
 there is a note in the Javadoc that Collections would like to have a directed 
hash table based BidiMaps.


My current implementation combines both tree and hash table approach: all 
"collision chains" are actually AVL-tree based "collision trees" so that even 
if hashing is really poor (or even constant), access/modification of data is no 
worse than O(log n). Also, I maintain an internal iteration list (like 
LinkedHashMap) that allows faster iteration and faster of relinking of nodes to 
new hash tables when expanding the hash tables.


Could someone take a look at my current source and tell me how that 
fits/doesn't fit into Collections?


Best regards,

Rodion E.

[https://avatars2.githubusercontent.com/u/1770505?v=3&s=400]

coderodde/BidirectionalHashMap
github.com
BidirectionalHashMap - My implementation of a bidirectional bijective hash map 
in Java