# Can java.util.regex.Pattern be used in a painless script?

**URL:** <https://discuss.elastic.co/t/can-java-util-regex-pattern-be-used-in-a-painless-script/213789>\
**Category:** Elasticsearch\
**Tags:** painless\
**Created:** [January 5, 2020, 6:06am UTC](https://discuss.elastic.co/t/can-java-util-regex-pattern-be-used-in-a-painless-script/213789 "2020-01-05T06:06:04Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Jamshid](https://avatars.discourse-cdn.com/v4/letter/j/ecd19e/32.png) [@Jamshid](https://discuss.elastic.co/u/Jamshid)\
**Post date:** [January 5, 2020, 6:06am UTC](https://discuss.elastic.co/t/can-java-util-regex-pattern-be-used-in-a-painless-script/213789/1 "2020-01-05T06:06:04Z")

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Is there a way to use java.util.regex.Pattern in a painless script? I get an error:

```
curl -i -XPOST http://localhost:9200/_scripts/painless/_execute -H 'Content-type: application/json' --data-binary '{"script": {"source": "return java.util.regex.Pattern.matches(\"a*b\",\"aaab\");", "params": { "test":1 } } }'

HTTP/1.1 500 Internal Server Error
content-type: application/json; charset=UTF-8
content-length: 668

{"error":{"root_cause":[{"type":"script_exception","reason":"compile error","script_stack":["... n java.util.regex.Pattern.matches(\"a*b\",\"aaab\");"," ^---- HERE"],"script":"return java.util.regex.Pattern.matches(\"a*b\",\"aaab\");","lang":"painless"}],"type":"script_exception","reason":"compile error","script_stack":["... n java.util.regex.Pattern.matches(\"a*b\",\"aaab\");"," ^---- HERE"],"script":"return java.util.regex.Pattern.matches(\"a*b\",\"aaab\");","lang":"painless","caused_by":{"type":"illegal_argument_exception","reason":"method [java.util.regex.Pattern, matches/2] not found"}},"status":500}

```

Other java.util classes seem to work:

```
curl -i -XPOST http://localhost:9200/_scripts/painless/_execute -H 'Content-type: application/json' --data-binary '{"script": {"source": "new java.util.BitSet(10).length();", "params": { "test":1 } } }'

HTTP/1.1 200 OK
content-type: application/json; charset=UTF-8
content-length: 14

{"result":"0"}

```

I know there is built-in regex support but that requires the pattern be a literal, hard-coded string. A native script I'm trying to port to painless needs to use a regex pattern string passed as a parameter.

---

<div class="post-metadata">

**Author:** ![spinscale](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/spinscale/32/25011_2.png) [@spinscale](https://discuss.elastic.co/u/spinscale)\
**Post date:** [January 8, 2020, 10:29am UTC](https://discuss.elastic.co/t/can-java-util-regex-pattern-be-used-in-a-painless-script/213789/2 "2020-01-08T10:29:43Z")

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please see [https://www.elastic.co/guide/en/elasticsearch/painless/7.5/painless-walkthrough.html#modules-scripting-painless-regex](https://www.elastic.co/guide/en/elasticsearch/painless/7.5/painless-walkthrough.html#modules-scripting-painless-regex) - especially about enabling regexes and how regexes are used. `Pattern.compile` is not included intentionally.

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [February 5, 2020, 10:29am UTC](https://discuss.elastic.co/t/can-java-util-regex-pattern-be-used-in-a-painless-script/213789/3 "2020-02-05T10:29:50Z")

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