# Cannot implement native script following the 2 popular instructions
**URL:** https://discuss.elastic.co/t/cannot-implement-native-script-following-the-2-popular-instructions/38133
**Category:** Elasticsearch
**Created:** [December 30, 2015, 1:35am UTC](https://discuss.elastic.co/t/cannot-implement-native-script-following-the-2-popular-instructions/38133 "2015-12-30T01:35:59Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@cuongvt101](https://discuss.elastic.co/u/cuongvt101)
#### Post date: [December 30, 2015, 1:35am UTC](https://discuss.elastic.co/t/cannot-implement-native-script-following-the-2-popular-instructions/38133/1 "2015-12-30T01:35:59Z")
I'm trying to use native script for custom scoring. There are two instructions I found:
- The first one:
[http://www.spacevatican.org/2012/5/12/elasticsearch-native-scripts-for-dummies/](http://www.spacevatican.org/2012/5/12/elasticsearch-native-scripts-for-dummies/)
When I run rake build, there's an error:
org/spacevatican/elasticsearchexample/CustomScript.java:22: error: cannot find symbol
double a = doc().numeric("a").getDoubleValue();
^ _(this one actually points at the "." after doc() )_
symbol: method numeric(String)
location: class DocLookup
1 error
- The 2nd link: [https://github.com/imotov/elasticsearch-native-script-example](https://github.com/imotov/elasticsearch-native-script-example)
I don't understand the instruction much, from the part "The parent project org.elasticsearch.plugin:plugins". Don't know where to find this parent project! May be because I'm very new to Java so I don't understand the structure here.
Can anyone jump in for some help? Thanks a lot!
---
### Author:  [@cuongvt101](https://discuss.elastic.co/u/cuongvt101)
#### Post date: [December 30, 2015, 7:00pm UTC](https://discuss.elastic.co/t/cannot-implement-native-script-following-the-2-popular-instructions/38133/2 "2015-12-30T19:00:53Z")
So I seem to get the 1st instruction work, via changing
`double a = doc().numeric("a").getDoubleValue();` to
`double a = (double) doc().get("a");`
Edit: I actually could compile, but query show error. Still trying to figure out!
The 2nd instruction, which has larger extend of examples and would better serve my need. But I don't get it either. Again, any help is highly appreciated. TIA.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 5, 2017, 11:27pm UTC](https://discuss.elastic.co/t/cannot-implement-native-script-following-the-2-popular-instructions/38133/3 "2017-07-05T23:27:41Z")