groovy - Groovy歧义方法重载

Question

早上好-我看到有类似的问题问过几次，但它们似乎都是针对已编译项目或涉及Gradle的项目。无论如何，我遇到了错误

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]

当我运行这个小脚本

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

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

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

这本身触发了

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()

我无法解决问题所在。据我所知，所有方法均正确完成，没有任何歧义。谁能指出我要去哪里了？

Answer 1

模棱两可的方法调用是BigDecimal的构造函数：

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

进一步说，一个可能的重载是 BigDecimal(String val)构造函数。我不确定 [class [C]到底指的是什么，但是我猜想它是指 BigDecimal(BigInteger val)的。

导致它的行可能是这一行：

new java.math.BigDecimal (settlement)

因为结算变量为null。在类似情况下，您可以像这样强制转换参数：

new java.math.BigDecimal (settlement as String)

但稍后可能会引发NullPointerException。因此，只需确保不将null传递给BigDecimal的构造函数即可。