Kotlin Notes

Custom Listeners

Define the listener

var onDismissListener: (() -> Unit)? = null

Invoke the listener

onDismissListener?.invoke()

Use the listener in another class

dialogRapidShortTimePicker.onDismissListener = {
     Timber.d("Dialog dismissed from helper")
     dismiss()
}

Interfaces for callbacks

Here is an interface used to open dialogs from HomeFragment since dialogs must be opened from a fragment or activity

Code in HomeFragment

At the type we define the Interface used for the listener

enum class DialogTypes {
    RAPID_SHORT_TIME,
    TIME_INPUT_HOUR
}

interface DialogListener {
    fun openDialog(type: DialogTypes)
}

class HomeFragment : Fragment(), LocationProvider, DialogListener {

//other code
...
override fun openDialog(type: DialogTypes) {
       Timber.i("openDialog type: $type")
       when (type) {
           DialogTypes.RAPID_SHORT_TIME -> {
               val dialogRapidShortTimeHelper = DialogRapidShortTimeHelper()
               dialogRapidShortTimeHelper.show(childFragmentManager, "dialog")
           }
           DialogTypes.TIME_INPUT_HOUR -> {
               val dialogTimeInputHourHelper = DialogTimeInputHourHelper()
               dialogTimeInputHourHelper.show(childFragmentManager, "dialog")
           }
       }
   }
}

In the class that we want to call the listener from

class SomeClass {
    var listener: DialogListener?=null

override fun onSingleTapConfirmed(event: MotionEvent): Boolean {
       val x = event.x.toInt()
       val y = event.y.toInt()
       Timber.v("onSingleTapConfirmed: $x, $y")
...
other code
...
segments[index].preTripSegment.durationClickArea.contains(x, y) -> {
    //this is the part that performs the callback
    listener?.openDialog(DialogTypes.RAPID_SHORT_TIME)
}