Groovy call to Java encode() with null = ambiguous method, but Java side is fine

Jae28 Sept

I moved my CSV export loop from Java to Groovy and now the job dies on the row with missing nickname. Java FieldEncoder has three encode overloads (String, Number, Collection), and null should become token NULL. In old Java code encoder.encode(user.getNickname()) works fine with null.

Groovy side:

def cells = COLUMNS.collect { col -> encoder.encode(row[col]) }

Row 3 has no nickname key. First line of the error say ambiguous method overloading, and the argument list is [null]. I print row[col] and it show null, so map looks normal. I also changed nullToken, no difference.

Is Groovy 4.0.22 returning something strange for missing key, or not supporting the null token option? Why Java handle null here but Groovy cannot?

Thanks for any help.

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Follow the reasoning

imke28 Sept Permalink
Java picks the overload at compile time from the static type, String here, so null is fine. Groovy dispatches at runtime, and a bare null matches String, Number and Collection equally. Cast it: encoder.encode((String) row[col]). Or add an encode(Object) overload.
teo_b28 Sept Permalink
imke is right. Groovy isn't returning anything strange, null is just null at runtime. Cast it, or use row[col] as String. Hit the same thing in a Gradle script calling my Java helper. Annoying. I'd add encode(Object) and handle null there, so the call site stays clean.
```
encoder.encode(row[col] as String)
```
Jae29 Sept Permalink
Thanks both, the cast works. But as String on a Number column, does it convert the value to text?

Groovy call to Java encode() with null = ambiguous method, but Java side is fine

The conversation continues 3

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