Modifying an anonymous function to invoke another anonymous function in Kotlin

问题

I have few click listeners in my code like below:

tvLogin.setOnClickListener {
    hideKeyBoard(it)
    login()
}

tvForgotPassword.setOnClickListener {
    hideKeyBoard(it)
    navigateToForgetPassword()
}

I want to modify the passed block of code to always invoke hideKeyBoard(view) and then my function.

Is there a way to create a higher order function that would modify a block of code and invoke passed function?

I have tried something like below:

val clickListener: (View,()->Unit) -> Unit 

But not sure how it would work.

Can anyone please help how to achieve?

回答1:

I'm not sure I understand fully what you mean, but maybe something like this:

fun addCallTo(lambda: (View) -> Unit): (View) -> Unit {
  return { 
    hideKeyboard(it)
    lambda(it)
  }
}

// usage:
tvLogin.setOnClickListener(addCallTo { view -> login() })

回答2:

You can extend View.OnClickListener and pass lambda to it:

inner class HideKeyboardClickListener(private val lambda: () -> Unit) : View.OnClickListener {
    override fun onClick(v: View) {
        hideKeyboard(v)
        lambda()
    }
}

And then set it like this:

tvForgotPassword.setOnClickListener(HideKeyboardClickListener {
    navigateToForgetPassword()
})

来源：https://stackoverflow.com/questions/50693148/modifying-an-anonymous-function-to-invoke-another-anonymous-function-in-kotlin