Java“lambda转换的目标类型必须是接口”
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Java "target type of lambda conversion must be an interface"
提问by Mocktheduck
I'm trying to use lambdas and streams in java but I'm quite new to it. I got this error in IntelliJ "target type of lambda conversion must be an interface" when I try to make a lambda expression
我正在尝试在 Java 中使用 lambdas 和流，但我对它很陌生。当我尝试创建 lambda 表达式时，我在 IntelliJ 中收到此错误“lambda 转换的目标类型必须是一个接口”
List<Callable<SomeClass>> callList = prgll.stream()
.map(p->(()->{return p.funct();} )) <--- Here I get error
.collect(Collectors.toList());
Am I doing something wrong?
难道我做错了什么？
采纳答案by Louis Wasserman
I suspect it's just Java's type inference not being quite smart enough. Try
我怀疑这只是 Java 的类型推断不够聪明。尝试
.map(p -> (Callable<SomeClass>) () -> p.funct())
回答by Bohemian
Stream#map()is a typedmethod, so you can explicitly specify the type:
Stream#map()是一种类型化方法，因此您可以显式指定类型：
.<Callable<SomeClass>>map(p -> () -> p.funct())
or neater, use a method reference:
或者更简洁，使用方法参考：
.<Callable<SomeClass>>map(p -> p::funct)
