Mapping wrong number of parameter from Gherkin features file to step definition - cucumber

Question

I had feature declaration like this:
Feature: find taxi and minicabs information
in order to get taxi and minicabs contact at given location
as application developer
I want to find tax and minicabs contact information at given location or query options
Scenario Outline: find taxi and minicabs contact information
Given Joe at location with <lat> and <lon>
When get all taxi and minicabs contacts information
Then should see list of taxi and minicabs
And all of them are at location with <lat> and <lon>
Examples:
| lat | lon |
| 51.490075 | -0.133226 |
And I had step definition like this:
#Given("^Joe at location with ([+-]?([0-9]+[.])?[0-9]+) and ([+-]?([0-9]+[.])?[0-9]+)$")
public void joeAtLocationWithLatAndLon(Number lat, Number lon) throws Throwable {
....
}
I expected I can received 2 parameters but Cucumber passed to me 4 parameters.
Error message as below:
with pattern [^Joe at location with ([+-]?([0-9]+[.])?[0-9]+) and ([+-]?([0-9]+[.])?[0-9]+)$] is declared with 2 parameters. However, the gherkin step has 4 arguments [51.490075, 51., -0.133226, 0.].
Do you have any idea about this? btw, I very appreciate if you can explain the way cucumber identify the number of parameters or share me any document about that.

Answer 1

The issue is the two inside brackets inside the regular expression. Using the current regex you will get 2 groups - one the whole "51.490075" and second "51." which matches the exp in the ([0-9]+[.]) part. Thus 4 arguments are created.
Remove the inside brackets and you will get just one argument for each, so two in total.
The next problem you are going to have is cucumber does not know how to transform String to Number class unless you tell it. For this you need to make use of the Transform annotation and create a specific class for this.
import cucumber.api.Transformer;
public class NumberTransformer extends Transformer<Number>{
#Override
public Number transform(String value) {
return Double.parseDouble(value);
}
}
#Given("^Joe at location with ([+-]?[0-9]+[.]?[0-9]+) and ([+-]?[0-9]+[.]?[0-9]+)$")
public void joeAtLocationWithAnd(#Transform(NumberTransformer.class)Number arg1, #Transform(NumberTransformer.class)Number arg2) throws Exception {
System.out.println(arg1);
System.out.println(arg2);
}
For the transforming issue you can also look up xstreams. If you are using cucumber 2, these kind of transformation is easier by using Xstreamconvertor annotation - https://github.com/cucumber/cucumber-jvm/pull/1010