Groovy ambiguous method overload

Question

Morning all - I see that similar questions have been asked a couple of times, but they all seem to be for compiled projects or those involving Gradle. Anyway, I'm getting the error

Caused by: javax.script.ScriptException: groovy.lang.GroovyRuntimeException: Ambiguous method overloading for method java.math.BigDecimal#<init>.
Cannot resolve which method to invoke for [null] due to overlapping prototypes between:
[class [C]
[class java.lang.String]

when I run this little script

String amt = "1"
String currency = "GBP"
String targetCurrency = "USD"

def settlement = crossCurrencyClient.crossCurrency(amt, currency, targetCurrency)

return transfer.amount * new java.math.BigDecimal (settlement)

which itself triggers this

import groovyx.net.http.HTTPBuilder
import groovyx.net.http.RESTClient
import groovy.json.JsonBuilder
import groovy.json.JsonOutput
import static groovyx.net.http.Method.GET
import static groovyx.net.http.ContentType.JSON

public class CrossCurrencyClient {

    def issuingAddress = "rBycsjqxD8RVZP5zrrndiVtJwht7Z457A8"
    String source = "rUR5QVHqFxRa8TSQawc1M6jKj7BvKzbHek" 
    String multiplier = ""
    def resURL = "http://url-string.com/v1/"
    def resourceIdClient = new RESTClient("${resURL}")

    public String generateUUID() {
        def resourceId = resourceIdClient.get(path:"uuid").data.uuid
        println "resourceId = " + resourceId
        return resourceId
        }

    public String crossCurrency(String amt,String currency,String targetCurrency) {

        def http = new HTTPBuilder( "${resURL}accounts/${source}/payments/paths/${source}/${amt}+${targetCurrency}+${issuingAddress}?source_currencies=${currency}+${issuingAddress}" 
)

        http.request(GET,JSON) {

            response.success = { resp, json -> 
                if(json.success){
                    multiplier = json?.source_amount?.value
                }
            }

            response.failure = { resp ->
                println "Request failed with status ${resp.status} and message : ${resp.message}"
                return "Something went wrong"
            }
        }
    return multiplier    
    }
}

CrossCurrencyClient crossCurrencyClient = new CrossCurrencyClient()

I can't work out what the problem is here. As far as I can see all the methods are done properly and there is no ambiguity. Can anyone point to where I'm going wrong?

Answer 1

The ambiguous method call is the BigDecimal's constructor:

Ambiguous method overloading for method java.math.BigDecimal#<init>

Further it says that one possible overload is the BigDecimal(String val) constructor. I am not sure what exactly does [class [C] refer to but I would guess it refers to the BigDecimal(BigInteger val).

The line that's causing it is probably this one:

new java.math.BigDecimal (settlement)

because the settlement variable is null. In similar situations you could just cast the parameter like so:

new java.math.BigDecimal (settlement as String)

but it will probably throw NullPointerException later. So just make sure you don't pass nulls to BigDecimal's constructor.