如何在kotlin中传递函数作为参数 - Android

Question

如何使用Kotlin在android中传递一个函数.如果我知道这样的功能,我能够通过:

fun a(b :() -> Unit){
}
fun b(){
}

我想传递任何函数,如 - >
fun passAnyFunc(fun : (?) ->Unit){}

Answer 1

您可以使用匿名函数或lambda,如下所示

fun main(args: Array<String>) {

    fun something(exec: Boolean, func: () -> Unit) {
        if(exec) {
            func()
        }
    }

    //Anonymous function
    something(true, fun() {
        println("bleh")
    })

    //Lambda
    something(true) {
        println("bleh")
    }

}

Answer 2

方法作为参数示例：

fun main(args: Array<String>) {
    // Here passing 2 value of first parameter but second parameter
    // We are not passing any value here , just body is here
    calculation("value of two number is : ", { a, b ->  a * b} );
}

// In the implementation we will received two parameter
// 1. message  - message 
// 2. lamda method which holding two parameter a and b
fun calculation(message: String, method_as_param: (a:Int, b:Int) -> Int) {
     // Here we get method as parameter and require 2 params and add value
     // to this two parameter which calculate and return expected value
     val result = method_as_param(10, 10);

     // print and see the result.
     println(message + result)
}