如何在方法引用(toString of Integer)上修复歧义类型? [英] How to fix ambiguous type on method reference (toString of an Integer)?
问题描述
执行此操作时
Stream.of(1, 32, 12, 15, 23).map(Integer::toString);
我收到一个模糊的类型错误。可以理解的是,编译器无法判断 toString(int)
或 toString()
是否来自整数
。
I get an ambiguous type error. Understandably, the compiler can't tell if I mean toString(int)
or toString()
from Integer
.
当不使用方法引用时,我可能已经通过显式转换或者写出泛型手,但我怎么能让编译器知道我的意思?我可以使用什么语法(如果有的话)来明确?
When not using a method reference, I might have gotten out of this with an explicit cast or write out the generics long hand, but how can I let the compiler know what I mean here? What syntax (if any) can I use to make in unambiguous?
推荐答案
无法使方法引用明确无误;简单地说,方法引用是仅支持明确的方法引用的功能。所以你有两个解决方案:
There is no way to make method references unambiguous; simply said, method references are a feature that is just supported for unambiguous method references only. So you have two solutions:
-
使用lambda表达式:
use a lambda expression:
Stream.of(1, 32, 12, 15, 23).map(i->Integer.toString(i));
(首选,至少是我)使用原始流 int
当源包含原始 int
值时的值:
(preferred, at least by me) Use a stream of primitive int
values when the source consists of primitive int
values only:
IntStream.of(1, 32, 12, 15, 23).mapToObj(Integer::toString);
这将使用静态 Integer.toString(int)
消耗 int
值的方法。
This will use the static Integer.toString(int)
method for consuming the int
values.
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