Kotlin:如何将函数作为参数传递给另一个? [英] Kotlin: how to pass a function as parameter to another?
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问题描述
给定函数 foo :
fun foo(m: String, bar: (m: String) -> Unit) {
bar(m)
}
我们可以:
foo("a message", { println("this is a message: $it") } )
//or
foo("a message") { println("this is a message: $it") }
现在,假设我们有以下功能:
Now, lets say we have the following function:
fun buz(m: String) {
println("another message: $m")
}
有没有办法将buz"作为参数传递给foo"?类似的东西:
Is there a way I can pass "buz" as a parameter to "foo" ? Something like:
foo("a message", buz)
推荐答案
使用 ::
表示一个函数引用,然后:
Use ::
to signify a function reference, and then:
fun foo(msg: String, bar: (input: String) -> Unit) {
bar(msg)
}
// my function to pass into the other
fun buz(input: String) {
println("another message: $input")
}
// someone passing buz into foo
fun something() {
foo("hi", ::buz)
}
自 Kotlin 1.1 起,您现在可以使用类成员(绑定可调用引用"),通过在函数引用操作符前加上实例:
Since Kotlin 1.1 you can now use functions that are class members ("Bound Callable References"), by prefixing the function reference operator with the instance:
foo("hi", OtherClass()::buz)
foo("hi", thatOtherThing::buz)
foo("hi", this::buz)
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