diff --git a/flutter_local_notifications/android/src/main/java/com/dexterous/flutterlocalnotifications/FlutterLocalNotificationsPlugin.java b/flutter_local_notifications/android/src/main/java/com/dexterous/flutterlocalnotifications/FlutterLocalNotificationsPlugin.java
index d417da74d..dcb2a66c8 100644
--- a/flutter_local_notifications/android/src/main/java/com/dexterous/flutterlocalnotifications/FlutterLocalNotificationsPlugin.java
+++ b/flutter_local_notifications/android/src/main/java/com/dexterous/flutterlocalnotifications/FlutterLocalNotificationsPlugin.java
@@ -84,9 +84,11 @@
 import java.util.Arrays;
 import java.util.Calendar;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 /** FlutterLocalNotificationsPlugin */
 @Keep
@@ -99,7 +101,9 @@ public class FlutterLocalNotificationsPlugin
   private static final String DRAWABLE = "drawable";
   private static final String DEFAULT_ICON = "defaultIcon";
   private static final String SELECT_NOTIFICATION = "SELECT_NOTIFICATION";
-  private static final String SCHEDULED_NOTIFICATIONS = "scheduled_notifications";
+  private static final String SCHEDULED_NOTIFICATIONS_FILE = "scheduled_notifications";
+  private static final String SCHEDULED_NOTIFICATIONS_STRING = "scheduled_notifications";
+  private static final String SCHEDULED_NOTIFICATIONS_SET = "scheduled_notifications_set";
   private static final String INITIALIZE_METHOD = "initialize";
   private static final String GET_CALLBACK_HANDLE_METHOD = "getCallbackHandle";
   private static final String ARE_NOTIFICATIONS_ENABLED_METHOD = "areNotificationsEnabled";
@@ -392,24 +396,63 @@ static Gson buildGson() {
   private static ArrayList<NotificationDetails> loadScheduledNotifications(Context context) {
     ArrayList<NotificationDetails> scheduledNotifications = new ArrayList<>();
     SharedPreferences sharedPreferences =
-        context.getSharedPreferences(SCHEDULED_NOTIFICATIONS, Context.MODE_PRIVATE);
-    String json = sharedPreferences.getString(SCHEDULED_NOTIFICATIONS, null);
-    if (json != null) {
+        context.getSharedPreferences(SCHEDULED_NOTIFICATIONS_FILE, Context.MODE_PRIVATE);
+    Set<String> jsonNotifications = getScheduledNotificationsJsonSet(sharedPreferences);
+    if (jsonNotifications != null) {
       Gson gson = buildGson();
-      Type type = new TypeToken<ArrayList<NotificationDetails>>() {}.getType();
-      scheduledNotifications = gson.fromJson(json, type);
+      Type type = new TypeToken<NotificationDetails>() {}.getType();
+      for (String json : jsonNotifications) {
+        scheduledNotifications.add(gson.fromJson(json, type));
+      }
+    }
+    return scheduledNotifications;
+  }
+
+  /**
+   * Get scheduled notifications from shared preferences, converting from old format if present.
+   *
+   * Returns null if neither are present
+   * The returned Set may not be mutated!
+   */
+  private static Set<String> getScheduledNotificationsJsonSet(SharedPreferences sharedPreferences) {
+    Set<String> jsonNotifications = sharedPreferences.getStringSet(SCHEDULED_NOTIFICATIONS_SET, null);
+    if (jsonNotifications != null) {
+      return jsonNotifications;
     }
+    String notificationsJson = sharedPreferences.getString(SCHEDULED_NOTIFICATIONS_STRING, null);
+    if (notificationsJson == null) {
+      return null;
+    }
+
+    // Convert (once) from the old format to the new format and delete the old
+    Gson gson = buildGson();
+    Type type = new TypeToken<ArrayList<NotificationDetails>>() {}.getType();
+    ArrayList<NotificationDetails> notificationsList = gson.fromJson(notificationsJson, type);
+    int amount = notificationsList.size();
+    String[] jsonNotificationsToSave = new String[amount];
+    for (int i = 0; i < amount; i++) {
+      jsonNotificationsToSave[i] = gson.toJson(notificationsList.get(i));
+    }
+    Set<String> scheduledNotifications = Set.of(jsonNotificationsToSave);
+    SharedPreferences.Editor editor = sharedPreferences.edit();
+    editor.remove(SCHEDULED_NOTIFICATIONS_STRING);
+    editor.putStringSet(SCHEDULED_NOTIFICATIONS_SET, scheduledNotifications);
+    editor.apply();
     return scheduledNotifications;
   }
 
   private static void saveScheduledNotifications(
       Context context, ArrayList<NotificationDetails> scheduledNotifications) {
     Gson gson = buildGson();
-    String json = gson.toJson(scheduledNotifications);
+    int amount = scheduledNotifications.size();
+    String[] jsonNotificationsToSave = new String[amount];
+    for (int i = 0; i < amount; i++) {
+      jsonNotificationsToSave[i] = gson.toJson(scheduledNotifications.get(i));
+    }
     SharedPreferences sharedPreferences =
-        context.getSharedPreferences(SCHEDULED_NOTIFICATIONS, Context.MODE_PRIVATE);
+        context.getSharedPreferences(SCHEDULED_NOTIFICATIONS_FILE, Context.MODE_PRIVATE);
     SharedPreferences.Editor editor = sharedPreferences.edit();
-    editor.putString(SCHEDULED_NOTIFICATIONS, json);
+    editor.putStringSet(SCHEDULED_NOTIFICATIONS_SET, Set.of(jsonNotificationsToSave));
     editor.apply();
   }
 
@@ -450,11 +493,8 @@ private static void scheduleNotification(
 
     AlarmManager alarmManager = getAlarmManager(context);
     if (BooleanUtils.getValue(notificationDetails.allowWhileIdle)) {
-      AlarmManagerCompat.setExactAndAllowWhileIdle(
-          alarmManager,
-          AlarmManager.RTC_WAKEUP,
-          notificationDetails.millisecondsSinceEpoch,
-          pendingIntent);
+      AlarmManagerCompat.setAlarmClock(
+          alarmManager, notificationDetails.millisecondsSinceEpoch, pendingIntent, pendingIntent);
     } else {
       AlarmManagerCompat.setExact(
           alarmManager,
@@ -492,8 +532,7 @@ private static void zonedScheduleNotification(
                 .toInstant()
                 .toEpochMilli();
     if (BooleanUtils.getValue(notificationDetails.allowWhileIdle)) {
-      AlarmManagerCompat.setExactAndAllowWhileIdle(
-          alarmManager, AlarmManager.RTC_WAKEUP, epochMilli, pendingIntent);
+      AlarmManagerCompat.setAlarmClock(alarmManager, epochMilli, pendingIntent, pendingIntent);
     } else {
       AlarmManagerCompat.setExact(alarmManager, AlarmManager.RTC_WAKEUP, epochMilli, pendingIntent);
     }
@@ -515,8 +554,8 @@ static void scheduleNextRepeatingNotification(
     PendingIntent pendingIntent =
         getBroadcastPendingIntent(context, notificationDetails.id, notificationIntent);
     AlarmManager alarmManager = getAlarmManager(context);
-    AlarmManagerCompat.setExactAndAllowWhileIdle(
-        alarmManager, AlarmManager.RTC_WAKEUP, notificationTriggerTime, pendingIntent);
+    AlarmManagerCompat.setAlarmClock(
+        alarmManager, notificationTriggerTime, pendingIntent, pendingIntent);
     saveScheduledNotification(context, notificationDetails);
   }
 
@@ -568,8 +607,8 @@ private static void repeatNotification(
     AlarmManager alarmManager = getAlarmManager(context);
 
     if (BooleanUtils.getValue(notificationDetails.allowWhileIdle)) {
-      AlarmManagerCompat.setExactAndAllowWhileIdle(
-          alarmManager, AlarmManager.RTC_WAKEUP, notificationTriggerTime, pendingIntent);
+      AlarmManagerCompat.setAlarmClock(
+          alarmManager, notificationTriggerTime, pendingIntent, pendingIntent);
     } else {
       alarmManager.setInexactRepeating(
           AlarmManager.RTC_WAKEUP, notificationTriggerTime, repeatInterval, pendingIntent);
@@ -610,18 +649,24 @@ private static long calculateRepeatIntervalMilliseconds(NotificationDetails noti
     return repeatInterval;
   }
 
+  // Note: This will now allow duplicate notifications on ID which would be overwritten before.
   private static void saveScheduledNotification(
       Context context, NotificationDetails notificationDetails) {
-    ArrayList<NotificationDetails> scheduledNotifications = loadScheduledNotifications(context);
-    ArrayList<NotificationDetails> scheduledNotificationsToSave = new ArrayList<>();
-    for (NotificationDetails scheduledNotification : scheduledNotifications) {
-      if (scheduledNotification.id.equals(notificationDetails.id)) {
-        continue;
-      }
-      scheduledNotificationsToSave.add(scheduledNotification);
+    SharedPreferences sharedPreferences =
+        context.getSharedPreferences(SCHEDULED_NOTIFICATIONS_FILE, Context.MODE_PRIVATE);
+    Set<String> jsonNotifications = getScheduledNotificationsJsonSet(sharedPreferences);
+    if (jsonNotifications == null) {
+      jsonNotifications = new HashSet<String>();
     }
-    scheduledNotificationsToSave.add(notificationDetails);
-    saveScheduledNotifications(context, scheduledNotificationsToSave);
+
+    // Mutations on the Set from getStringSet() are not allowed!
+    Set<String> jsonNotificationsToSave = new HashSet<String>(jsonNotifications);
+
+    Gson gson = buildGson();
+    jsonNotificationsToSave.add(gson.toJson(notificationDetails));
+    SharedPreferences.Editor editor = sharedPreferences.edit();
+    editor.putStringSet(SCHEDULED_NOTIFICATIONS_SET, jsonNotificationsToSave);
+    editor.apply();
   }
 
   private static int getDrawableResourceId(Context context, String name) {
@@ -1619,7 +1664,11 @@ private void cancelAllNotifications(Result result) {
       alarmManager.cancel(pendingIntent);
     }
 
-    saveScheduledNotifications(applicationContext, new ArrayList<>());
+    SharedPreferences sharedPreferences =
+            applicationContext.getSharedPreferences(SCHEDULED_NOTIFICATIONS_FILE, Context.MODE_PRIVATE);
+    SharedPreferences.Editor editor = sharedPreferences.edit();
+    editor.remove(SCHEDULED_NOTIFICATIONS_SET);
+    editor.apply();
     result.success(null);
   }