# Java api question **URL:** \ **Category:** Elasticsearch\ **Created:** [April 8, 2015, 1:58pm UTC](https://discuss.elastic.co/t/java-api-question/23151 "2015-04-08T13:58:56Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![bitsofinfo](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/bitsofinfo/32/459_2.png) [@bitsofinfo](https://discuss.elastic.co/u/bitsofinfo)\ **Post date:** [April 8, 2015, 1:58pm UTC](https://discuss.elastic.co/t/java-api-question/23151/1 "2015-04-08T13:58:56Z")
Hi, Just started doing some development w/ the Java API and one thing I immediately noticed are things like this [http://javadoc.kyubu.de/elasticsearch/v1.4.2/org/elasticsearch/common/collect/ImmutableOpenMap.html](http://javadoc.kyubu.de/elasticsearch/v1.4.2/org/elasticsearch/common/collect/ImmutableOpenMap.html) Why does something like ImmutableOpenMap not implement "Map"? -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/6ce43f50-f6f6-46b4-802a-5730d3ab448e%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/6ce43f50-f6f6-46b4-802a-5730d3ab448e%40googlegroups.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![jprante](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jprante/32/44941_2.png) [@jprante](https://discuss.elastic.co/u/jprante)\ **Post date:** [April 8, 2015, 2:20pm UTC](https://discuss.elastic.co/t/java-api-question/23151/2 "2015-04-08T14:20:08Z")
Elasticsearch uses HPPC. Please read about it at > **[HPPC: High Performance Primitive Collections for Java](http://labs.carrotsearch.com/hppc.html)** > > Carrot Search Labs: High Performance Primitive Collections for Java, JUnit benchmarking, Suffix Arrays for Java, CSS sprites In order to minimize footprint on memory (autoboxing, primitive types) and to increase performance with less garbage collection, HPPC collections do not implement Java Collection API, but their own HPPC API. Jörg On Wed, Apr 8, 2015 at 3:58 PM, [bitsofinfo.g@gmail.com](mailto:bitsofinfo.g@gmail.com) wrote: > Hi, > Just started doing some development w/ the Java API and one thing I > immediately noticed are things like this > > [http://javadoc.kyubu.de/elasticsearch/v1.4.2/org/elasticsearch/common/collect/ImmutableOpenMap.html](http://javadoc.kyubu.de/elasticsearch/v1.4.2/org/elasticsearch/common/collect/ImmutableOpenMap.html) > > Why does something like ImmutableOpenMap not implement "Map"? > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > To view this discussion on the web visit > [https://groups.google.com/d/msgid/elasticsearch/6ce43f50-f6f6-46b4-802a-5730d3ab448e%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/6ce43f50-f6f6-46b4-802a-5730d3ab448e%40googlegroups.com) > [https://groups.google.com/d/msgid/elasticsearch/6ce43f50-f6f6-46b4-802a-5730d3ab448e%40googlegroups.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/6ce43f50-f6f6-46b4-802a-5730d3ab448e%40googlegroups.com?utm_medium=email&utm_source=footer) > . > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/CAKdsXoH7uiEvPStr5rCqyfQxU7%2BrQ-FDRfkz\_T%3DAeXYMeXqPWA%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAKdsXoH7uiEvPStr5rCqyfQxU7%2BrQ-FDRfkz_T%3DAeXYMeXqPWA%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 12:20am UTC](https://discuss.elastic.co/t/java-api-question/23151/3 "2017-07-06T00:20:51Z")
Closed on July 6, 2017, 12:20am UTC