Question

当我尝试使用包含带有功能参数的重载方法的代码时，我得到Ambiguous error。

我写了一个小片段，显示了一个模棱两可的行为：

import java.util.function.BiConsumer
import java.util.function.Consumer

class Test {

    static void main(String... args) {
        execute({ x -> println("Consumer") })
        execute({ x, y -> println("BiConsumer") })
    }

    static void execute(Consumer<Integer> c) {
        c.accept(100)
    }

    static void execute(BiConsumer<Integer, Integer> c) {
        c.accept(1, 2)
    }
}

输出（2.4.9 groovy）：

    Exception in thread "main" groovy.lang.GroovyRuntimeException: Ambiguous method overloading for method Test#execute.
Cannot resolve which method to invoke for [class Test$_main_closure1] due to overlapping prototypes between:
    [interface java.util.function.BiConsumer]
    [interface java.util.function.Consumer]
    at groovy.lang.MetaClassImpl.chooseMostSpecificParams(MetaClassImpl.java:3268)
    at groovy.lang.MetaClassImpl.chooseMethodInternal(MetaClassImpl.java:3221)
    at groovy.lang.MetaClassImpl.chooseMethod(MetaClassImpl.java:3164)
    at groovy.lang.MetaClassImpl.pickStaticMethod(MetaClassImpl.java:1516)
    at groovy.lang.MetaClassImpl.retrieveStaticMethod(MetaClassImpl.java:1412)
    at org.codehaus.groovy.vmplugin.v7.Selector$MethodSelector.chooseMeta(Selector.java:553)
    at org.codehaus.groovy.vmplugin.v7.Selector$MethodSelector.setCallSiteTarget(Selector.java:954)
    at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:228)
    at Test.main(Test.groovy:7)

但它适用于java-lambdas，我不明白在这种情况下如何使用groovy-closures。

Answer 1

您需要在关闭后放置as XXX，以便为运行时提供您想要去的线索

    execute({ x -> println("Consumer") } as Consumer)
    execute({ x, y -> println("BiConsumer") } as BiConsumer)

应该这样做

Answer 2

也许使用Closure：

execute(Closure <Integer> c) {
  c (10)
}

execute (Closure <Integer, Integer> c) {
  c (10, 30)
}

具有功能参数的Groovy闭包和重载方法

2 个答案: