[
https://issues.apache.org/jira/browse/COLLECTIONS-393?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13218894#comment-13218894
]
Chris Shayan commented on COLLECTIONS-393:
--
the class is like this:
package dk.sebpension;
import java.util.AbstractList;
import java.util.List;
/**
* Split / Partition a collection into smaller collections Inspired by Lars
* Vogel
*/
public final class Partition extends AbstractList> {
final List list;
final int size;
public Partition(List list, int size) {
this.list = list;
this.size = size;
}
@Override
public List get(int index) {
int listSize = size();
if (listSize < 0) {
throw new IllegalArgumentException("negative size: " +
listSize);
}
if (index < 0) {
throw new IndexOutOfBoundsException("index " + index
+ " must not be negative");
}
if (index >= listSize) {
throw new IndexOutOfBoundsException("index " + index
+ " must be less than size " +
listSize);
}
int start = index * size;
int end = Math.min(start + size, list.size());
return list.subList(start, end);
}
@Override
public int size() {
return (list.size() + size - 1) / size;
}
@Override
public boolean isEmpty() {
return list.isEmpty();
}
/**
* Returns consecutive {@linkplain List#subList(int, int) sublists} of a
* list, each of the same size (the final list may be smaller). For
example,
* partitioning a list containing {@code [a, b, c, d, e]} with a
partition
* size of 3 yields {@code [[a, b, c], [d, e]]} -- an outer list
containing
* two inner lists of three and two elements, all in the original order.
*
*
* The outer list is unmodifiable, but reflects the latest state of the
* source list. The inner lists are sublist views of the original list,
* produced on demand using {@link List#subList(int, int)}, and are
subject
* to all the usual caveats about modification as explained in that API.
*
* Adapted from http://code.google.com/p/google-collections/ * @param
*
* @param list
*the list to return consecutive sublists of
* @param size
*the desired size of each sublist (the last may be smaller)
* @return a list of consecutive sublists
*/
public static List> partition(List list, int size) {
if (list == null) {
throw new NullPointerException("'list' must not be
null");
}
if (!(size > 0)) {
throw new IllegalArgumentException("'size' must be
greater than 0");
}
return new Partition(list, size);
}
}
and example of it is:
List> strings = Partition.partition(raws,
5);
for (List list : strings) {
//
}
> Split / Partition a collection into smaller collections
> ---
>
> Key: COLLECTIONS-393
> URL: https://issues.apache.org/jira/browse/COLLECTIONS-393
> Project: Commons Collections
> Issue Type: New Feature
> Components: Collection
>Reporter: Chris Shayan
> Attachments: Partition.java
>
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> Returns consecutive sublists of a list, each of the same size (the final list
> may be smaller). For example, partitioning a list containing [a, b, c, d, e]
> with a partition size of 3 yields [[a, b, c], [d, e]] -- an outer list
> containing two inner lists of three and two elements, all in the original
> order.
> The outer list is unmodifiable, but reflects the latest state of the source
> list. The inner lists are sublist views of the original list, produced on
> demand using List.subList(int, int), and are subject to all the usual caveats
> about modification as explained in that API. Adapted from
> http://code.google.com/p/google-collections/
> Inspired by Lars Vogel
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