在kotlin中作为参数使用默认参数

Question

i have a function who have another function as parameter, and i want to set default function to my function parameter.

here i have a function like this

public fun showDialog(context: Context, title: String = "-", mode: String = "info", type: String = "info", onOk : (dialog: Dialog) -> Unit = { onClickOk(dialog)) }) {

val dialog = Dialog(context)
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE)
dialog.setCancelable(false)
dialog.setContentView(R.layout.modal_dialog)
dialog.window.setBackgroundDrawable(ColorDrawable(Color.TRANSPARENT))

dialog.dialogText.text = title

if (mode.equals("dialog")) {
    dialog.dialogYesNo.visibility = View.VISIBLE
    dialog.optionOk.visibility = View.GONE
} else {
    dialog.dialogYesNo.visibility = View.GONE
    dialog.optionOk.visibility = View.VISIBLE
}

if (type.equals("success")) {
    dialog.optionOk.background = context.getDrawable(R.drawable.btn_rounded_success)
    dialog.dialogAlert.background = context.getDrawable(R.drawable.dialog_alert_success)
} else if (type.equals("fail")) {
    dialog.optionOk.background = context.getDrawable(R.drawable.btn_rounded_fail)
    dialog.dialogAlert.background = context.getDrawable(R.drawable.dialog_alert_fail)
} else {
    dialog.optionOk.background = context.getDrawable(R.drawable.btn_rounded_primary)
    dialog.dialogAlert.background = context.getDrawable(R.drawable.dialog_alert_info)
}

dialog.optionOk.setOnClickListener{
    onOk(dialog)
}

dialog.show()
}

and here my onClickOk function

public fun onClickOk (dialog: Dialog){
    dialog.hide()
}

my function as parameter is in this code :

onOk : (dialog: Dialog) -> Unit

and i give a default argument to my function parameter in this code

onOk : (dialog: Dialog) -> Unit = { onClickOk(dialog)) }

but i can't passing the "dialog" parameter on onOk function to onClickOk function

this is my error code screenshot

can someone help me please ? Thanks

Answer 1

您可以传递方法参考：

onOk : (dialog: Dialog) -> Unit = this::onClickOk

Answer 2

Names in the function type notation are only for the documentation purposes and you won't be able to use them in the lambda's body:

The function type notation can optionally include names for the function parameters: (x: Int, y: Int) -> Point. These names can be used for documenting the meaning of the parameters

If your lambda has only one argument, you can use an implicit it parameter to refer to the argument:

onOk: (dialog: Dialog) -> Unit = { onClickOk(it) }

In case of two or more arguments you have to declare them inside the lambda's body:

onOk: (Dialog, String) -> Unit = { dialog, title -> onClickOk(dialog, title) }