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https://issues.apache.org/jira/browse/COLLECTIONS-858?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Gary D. Gregory resolved COLLECTIONS-858.
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Fix Version/s: 4.5.0-M3
Resolution: Fixed
> CartesianProductIterator
> ------------------------
>
> Key: COLLECTIONS-858
> URL: https://issues.apache.org/jira/browse/COLLECTIONS-858
> Project: Commons Collections
> Issue Type: New Feature
> Components: Iterator
> Reporter: Alexey Pelykh
> Priority: Trivial
> Fix For: 4.5.0-M3
>
>
> The {{CartesianProductIterator}} is suitable to enhance a deeply-nested
> for-loops over a set of collections.
> Given
> {code:java}
> var a = new Arrays.asList('a1', 'a2', 'a3');
> var b = new Arrays.asList('b1', 'b2', 'b3');
> var c = new Arrays.asList('c1', 'c2', 'c3');
> var d = new Arrays.asList('d1', 'd2', 'd3');
> var e = new Arrays.asList('e1', 'e2', 'e3');
> var f = new Arrays.asList('f1', 'f2', 'f3');
> {code}
>
> instead of
> {code:java}
> for (var aElement : a) {
> for (var bElement : b) {
> for (var cElement : c) {
> for (var dElement : d) {
> for (var eElement : e) {
> for (var fElement : f) {
> // ...
> }
> }
> }
> }
> }
> }
> {code}
> it would look like:
> {code:java}
> var it = new CartesianProductIterator<>(a, b, c, d, e, f);
> while (it.hasNext()) {
> var elements = it.next();
> }
> {code}
>
> Extremely useful for nesting levels 10+.
> [https://github.com/apache/commons-collections/pull/509]
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