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Subdividing a Collection into smaller collections  RSS feed

 
Ranch Hand
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Here is the requirement I have to split a collection into n collections each of a given size. Here is the code, I came up with. I am guessing there is a better way to do this or is there a Collection Utility that does it for me. I looked but could not find it (did a google search and Java ranch search).
Any pointers would be great and thanks for your time.
 
Promod kumar
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I actually found a sublist after I posted the message. Is that the better way of doing this.
 
Ranch Hand
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IBM DB2 Eclipse IDE Spring
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public class CollectionSplitter {

static List split(List srcList, int index) {
List d = new ArrayList();
for (int i = 0; i < srcList.size(); i = i + 4) {
if ((i + 4) <= srcList.size())
d.add(srcList.subList(i, i + 4));
else
d.add(srcList.subList(i, srcList.size() - 1));
}
return d;
}

public static void main(String[] args) {
List resultList = new ArrayList();
List list = new ArrayList();
list.add("one");
list.add("two");
list.add("three");
list.add("four");
list.add("five");
list.add("six");
list.add("seven");
list.add("eight");
list.add("nine");
list.add("ten");
list.add("eleven");
resultList = split(list, 5);
}
}

if there is still simple let me know
 
Promod kumar
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Gowtham,
Yours looks simple. Anyway here is my new version

 
Greenhorn
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How about something like

 
Greenhorn
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I realise this an old post but it comes up high in web searches for this topic.

So, here is an alternative solution basically adapted from the google collections apis. It uses generics to return a list of lists which are of the specified size. Just call the static method partition() with your parameters.


 
Ranch Hand
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Hello,

thanks this discussion was helpful. Based on your discussion I have created a little summary and a JUnit test which can be found here:
http://www.vogella.de/articles/JavaAlgorithmsPartitionCollection/article.html

I did include this discussion as the source of information in the article.

Thanks again, Lars
 
Greenhorn
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Niran Abeygunawardena wrote:I realise this an old post but it comes up high in web searches for this topic.

So, There is another alternative solution by using enumerations and not instantiating multiple list objects at once .


 
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