Fixed TimePickerFragment.kt crashing on configuration change by parcelising OnTimeSetListener interface - I didn't even know that that was possible tbh; fragments now use childFragmentManager instead of the activity's supportFragmentManager to instantiate bottom sheets

app/src/main/java/com/denizk0461/studip/dialog/TimePickerFragment.kt

@@ -4,21 +4,29 @@ import android.app.Dialog
 import androidx.fragment.app.DialogFragment
 import android.app.TimePickerDialog
 import android.os.Bundle
+import android.os.Parcelable
 import android.widget.TimePicker
+import com.denizk0461.studip.data.getParcelableCompat
 
 /**
- * Dialogue used for letting the user pick a timestamp. TODO crashes on config change (multitask)
- *
- * @param listener      listener for when the user finishes setting a time
- * @param isEventStart  whether the timestamp to be edited is the start of the event
+ * Dialogue used for letting the user pick a timestamp.
  */
-class TimePickerFragment(
-    private val listener: OnTimeSetListener,
-    private val isEventStart: Boolean,
-) : DialogFragment(), TimePickerDialog.OnTimeSetListener {
+class TimePickerFragment : DialogFragment(), TimePickerDialog.OnTimeSetListener {
+
+    private lateinit var listener: OnTimeSetListener
+    private var isEventStart: Boolean = false
 
     override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
+
+        // Retrieve listener for when the user finishes setting a time
+        listener = arguments.getParcelableCompat("interface")
+
+        // Retrieve whether the timestamp to be edited is the start of the event
+        isEventStart = arguments?.getBoolean("isEventStart") == true
+
+        // Retrieve timestamp to edit
         val timestampSplit = (arguments?.getString("timestamp") ?: "").split(":")
+
         return TimePickerDialog(
             activity,
             this,
@@ -28,11 +36,19 @@ class TimePickerFragment(
         )
     }
 
+    /**
+     * Override the implementation of TimePickerDialog#OnTimeSetListener.
+     */
+    override fun onTimeSet(picker: TimePicker?, hours: Int, minutes: Int) {
+        // Use custom implementation of OnTimeSetListener
+        listener.onTimeSet(hours, minutes, isEventStart)
+    }
+
     /**
      * Custom implementation of TimePickerDialog#OnTimeSetListener that includes a boolean to find
      * out whether the start or the end timestamp has been edited.
      */
-    interface OnTimeSetListener {
+    interface OnTimeSetListener : Parcelable {
 
         /**
          * Timestamp has been edited by the user.
@@ -43,12 +59,4 @@ class TimePickerFragment(
          */
         fun onTimeSet(hours: Int, minutes: Int, isEventStart: Boolean)
     }
-
-    /**
-     * Override the implementation of TimePickerDialog#OnTimeSetListener.
-     */
-    override fun onTimeSet(picker: TimePicker?, hours: Int, minutes: Int) {
-        // Use custom implementation of OnTimeSetListener
-        listener.onTimeSet(hours, minutes, isEventStart)
-    }
 }

app/src/main/java/com/denizk0461/studip/fragment/AppFragment.kt

@@ -2,7 +2,6 @@ package com.denizk0461.studip.fragment
 
 import android.content.Context
 import androidx.fragment.app.Fragment
-import androidx.fragment.app.FragmentActivity
 import com.denizk0461.studip.sheet.AppSheet
 
 /**
@@ -30,6 +29,6 @@ open class AppFragment : Fragment() {
      * @param sheet element that will be displayed
      */
     protected fun openBottomSheet(sheet: AppSheet) {
-        sheet.show((context as FragmentActivity).supportFragmentManager, sheet.javaClass.simpleName)
+        sheet.show(childFragmentManager, sheet.javaClass.simpleName)
     }
 }

app/src/main/java/com/denizk0461/studip/sheet/ScheduleUpdateSheet.kt

@@ -1,6 +1,8 @@
 package com.denizk0461.studip.sheet
 
 import android.os.Bundle
+import android.os.Parcel
+import android.os.Parcelable
 import android.view.View
 import android.view.ViewGroup
 import androidx.appcompat.widget.PopupMenu
@@ -26,7 +28,7 @@ import com.denizk0461.studip.viewmodel.ScheduleUpdateViewModel
 /**
  * Update sheet to allow the user to edit attributes for a specific schedule event.
  */
-class ScheduleUpdateSheet : AppSheet(R.layout.sheet_schedule_update), TimePickerFragment.OnTimeSetListener {
+class ScheduleUpdateSheet() : AppSheet(R.layout.sheet_schedule_update), TimePickerFragment.OnTimeSetListener {
 
     // Editable fields
     private var timeslotStart = "12:00"
@@ -48,6 +50,15 @@ class ScheduleUpdateSheet : AppSheet(R.layout.sheet_schedule_update), TimePicker
     // Day the event is scheduled for, default is Monday
     private var selectedDay = 0
 
+    constructor(parcel: Parcel) : this() {
+        timeslotStart = parcel.readString() ?: ""
+        timeslotEnd = parcel.readString() ?: ""
+        colour = parcel.readInt()
+        hasClickedDelete = parcel.readByte() != 0.toByte()
+        isEditing = parcel.readByte() != 0.toByte()
+        selectedDay = parcel.readInt()
+    }
+
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
 
@@ -274,11 +285,10 @@ class ScheduleUpdateSheet : AppSheet(R.layout.sheet_schedule_update), TimePicker
         binding.buttonTimeStart.text = timeslotStart
         binding.buttonTimeStart.setOnClickListener {
             // Launch a time picker dialogue to pick a new start timestamp
-            TimePickerFragment(
-                this,
-                true,
-            ).also { sheet ->
+            TimePickerFragment().also { sheet ->
                 val bundle = Bundle()
+                bundle.putParcelable("interface", this)
+                bundle.putBoolean("isEventStart", true)
                 bundle.putString("timestamp", binding.buttonTimeStart.text.toString())
                 sheet.arguments = bundle
             }.show((context as FragmentActivity).supportFragmentManager, "timePicker")
@@ -286,11 +296,10 @@ class ScheduleUpdateSheet : AppSheet(R.layout.sheet_schedule_update), TimePicker
         binding.buttonTimeEnd.text = timeslotEnd
         binding.buttonTimeEnd.setOnClickListener {
             // Launch a time picker dialogue to pick a new end timestamp
-            TimePickerFragment(
-                this,
-                false,
-            ).also { sheet ->
+            TimePickerFragment().also { sheet ->
                 val bundle = Bundle()
+                bundle.putParcelable("interface", this)
+                bundle.putBoolean("isEventStart", false)
                 bundle.putString("timestamp", binding.buttonTimeEnd.text.toString())
                 sheet.arguments = bundle
             }.show((context as FragmentActivity).supportFragmentManager, "timePicker")
@@ -398,4 +407,27 @@ class ScheduleUpdateSheet : AppSheet(R.layout.sheet_schedule_update), TimePicker
         } else {
             View.GONE
         }
+
+    override fun writeToParcel(parcel: Parcel, flags: Int) {
+        parcel.writeString(timeslotStart)
+        parcel.writeString(timeslotEnd)
+        parcel.writeInt(colour)
+        parcel.writeByte(if (hasClickedDelete) 1 else 0)
+        parcel.writeByte(if (isEditing) 1 else 0)
+        parcel.writeInt(selectedDay)
+    }
+
+    override fun describeContents(): Int {
+        return 0
+    }
+
+    companion object CREATOR : Parcelable.Creator<ScheduleUpdateSheet> {
+        override fun createFromParcel(parcel: Parcel): ScheduleUpdateSheet {
+            return ScheduleUpdateSheet(parcel)
+        }
+
+        override fun newArray(size: Int): Array<ScheduleUpdateSheet?> {
+            return arrayOfNulls(size)
+        }
+    }
 }