[英]How to use existing comparators in Kotlin
@Suppress("UNCHECKED_CAST")
val comp = Integer::compare as Comparator<Int>
Results in: 结果是:
java.lang.ClassCastException:
org.organicdesign.fp.xform.TransformableTest$testToImSortedSet$comp$1
cannot be cast to java.util.Comparator
I can do this: 我可以做这个:
val comp = Comparator{ a:Int, b:Int -> Integer.compare(a, b) }
or 要么
val comp = Comparator{ a:Int, b:Int -> a.compareTo(b) }
But is there a better way? 但是有更好的方法吗? I feel like I shouldn't have to create a new wrapper function for this.
我觉得我不必为此创建新的包装函数。
You can use a function reference , and instead of 您可以使用函数引用 ,而不是
val comp = Comparator { a: Int, b: Int -> Integer.compare(a, b) }
... just write this: ...只需这样写:
val comp = Comparator(Integer::compare)
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