Comments on: Google Collections

By: A Generic Method For Sorting (Google Collections) Multiset Per Entry Count « Java. Internet. Algorithms. Ideas.

Sat, 20 Feb 2010 17:47:45 +0000

[...] used google collections, in addition to the official website, you might find those tutorials (1 and 2) useful for an [...]

By: Deepak

Deepak — Tue, 16 Feb 2010 15:55:39 +0000

Good stuff, I tried to explore basic aspects in this article – http://www.myhomepageindia.com/index.php/2010/01/07/google-collection-types.html

By: Roger Schildmeijer

Roger Schildmeijer — Tue, 27 Oct 2009 20:12:34 +0000

http://code.google.com/p/guava-libraries/

By: Sune Simonsen

Sune Simonsen — Mon, 26 Oct 2009 09:11:28 +0000

Thanks to all of you, I’m really happy you liked the article.

To you Phil, I can’t come up with a better way than to sort by occurrences as you mentioned:

Function, Integer> getCountFunction =
    new Function, Integer>() {
      public Integer apply(Multiset.Entry from) {
        return from.getCount();
      }
    };

Ordering> popular =
Ordering.natural().reverse().onResultOf(getCountFunction);

List> sorted =
popular.sortedCopy(fruits.entrySet());

for (Multiset.Entry entry : sorted) {
System.out.println(String.format(“%s %s”, entry.getCount(),
entry.getElement()));
}

4: Yellow Banana
3: Red Strawberry
2: Green Kiwifruit
2: Red Tomato
1: Yellow Lemon

By: phil

phil — Sun, 25 Oct 2009 21:26:17 +0000

As you guessed, I meant “multiset” and not multimap in my example.
Thanks.

By: phil

phil — Sun, 25 Oct 2009 21:24:22 +0000

Excellent post!
I have a question. Do you know a way to sort a multiset based on the number of occurrence of each elements?
For instance if your multimap is
apple -> 1
tomato ->5
you would like to see tomato first.
I can’t find an easy way to do that operation that seems to me very usefull.
In the meantime I used a comparator as follow

Comparator occurence_comparator = new Comparator() {
public int compare(Multiset.Entry e1, Multiset.Entry e2) {
return e2.getCount() – e1.getCount() ;
}
};

Is there a more generic and elegant way to do it?
Thanks!
-Phil.

By: sachin Misurkar

sachin Misurkar — Sat, 24 Oct 2009 15:34:52 +0000

Thanks for sharing such new and useful info.

By: Anshu Mishra

Anshu Mishra — Fri, 23 Oct 2009 20:06:54 +0000

Thanks for the post. I was planning to explore it since the first time I saw it presented by Bob Lee and Josh Bloch. Good work !

Nice introduction.

By: Benjamin Winterberg

Benjamin Winterberg — Fri, 23 Oct 2009 08:36:56 +0000

This is a nice addition to this introduction to google collections:
http://bwinterberg.blogspot.com/2009/09/introduction-to-google-collections.html

By: Krzysztof Białek

Krzysztof Białek — Fri, 23 Oct 2009 08:36:42 +0000

Very nice introduction. It seems to be inspired by Scala collections a lot. It’s a pity that functions definitions need so much boilerplate in Java. Thanks a lot.