Attempt to get app to work properly when in the background in newer versions of Android, with assistance from qwen3.6:35b. Testing TBD.

app/src/main/AndroidManifest.xml

@@ -1,6 +1,15 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
 
+    <!-- 🔊 Required to play sound while backgrounded & bypass Doze -->
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <!-- Android 14 requires declaring foreground service types -->
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_MEDIA_PLAYBACK" />
+    
+    <!-- ⏰ Android 12+ exact alarm permission (users can deny, code handles it gracefully) -->
+    <uses-permission android:name="android.permission.SCHEDULE_EXACT_ALARM" />
+
     <application
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"
@@ -8,6 +17,7 @@
         android:supportsRtl="true"
         android:theme="@style/InfiniteTimer"
         android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize">
+        
         <activity android:name=".MainActivity" android:exported="true">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
@@ -15,13 +25,14 @@
             </intent-filter>
         </activity>
 
-        <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
-        <uses-permission android:name="android.permission.FOREGROUND_SERVICE_MEDIA_PLAYBACK" />
+        <!-- 🔔 Register the receiver that triggers the alarm response -->
+        <receiver android:name=".TimerReceiver" 
+            android:exported="false" />
             
-        <service
-            android:name=".Alert"
+        <!-- 🎵 Transient service to play audio & hold WakeLock -->
+        <service android:name=".TimerForegroundService"
             android:foregroundServiceType="mediaPlayback"
             android:exported="false" />
-    </application>
 
+    </application>
 </manifest>

app/src/main/java/com/hyperling/apps/infinitetimer/Alert.java

@@ -1,125 +1,85 @@
 package com.hyperling.apps.infinitetimer;
 
-import android.app.Notification;
-import android.app.NotificationChannel;
-import android.app.NotificationManager;
+import android.app.AlarmManager;
 import android.app.PendingIntent;
-import android.app.Service;
+import android.content.Context;
 import android.content.Intent;
-import android.media.MediaPlayer;
-import android.media.RingtoneManager;
-import android.net.Uri;
 import android.os.Build;
-import android.os.Handler;
-import android.os.IBinder;
-import android.os.Looper;
-import android.support.v4.app.NotificationCompat;
+import android.provider.Settings;
 import android.util.Log;
 
-public class Alert extends Service {
+public class Alert {
+    private static final String TAG = "Alert";
+    public static final String ACTION_TIMER = "com.hyperling.apps.infinitetimer.ACTION_TIMER";
     
-    boolean DEBUG = true;
-    String TAG = "Alert.", tag;
-    private static final String CHANNEL_ID = "alert_service_channel";
-    private static final int NOTIFICATION_ID = 1;
+    /**
+     * Sets a persistent alarm that triggers the TimerReceiver.
+     * Uses setExactAndAllowWhileIdle to bypass Android Doze mode.
+     */
+    public static void start(Context context, long intervalMs) {
+        Intent intent = new Intent(context, TimerReceiver.class);
+        intent.setAction(ACTION_TIMER);
 
-    Uri ringtoneUri;
-    private MediaPlayer mediaPlayer;
-    private Handler handler = new Handler(Looper.getMainLooper());
-    private long intervalMs; // user-defined frequency
-
-    private final Runnable alertRunnable = new Runnable() {
-        @Override
-        public void run() {
-            playAlert();
-            handler.postDelayed(this, intervalMs);
-        }
-    };
-
-    @Override
-    public int onStartCommand(Intent intent, int flags, int startId) {
-        tag = TAG + "onStartCommand";
-
-        if (intent != null) {
-            intervalMs = intent.getLongExtra("interval_ms", 5000L);
+        // FLAG_IMMUTABLE required for Android 12+ (API 31+)
+        int flags = PendingIntent.FLAG_UPDATE_CURRENT | PendingIntent.FLAG_CANCEL_CURRENT;
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+            flags |= PendingIntent.FLAG_IMMUTABLE;
         }
 
-        createNotificationChannel();
-        startForeground(NOTIFICATION_ID, buildNotification());
+        PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, flags);
+        AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
 
-        // Start the alert loop (your original Runnable logic)
-        handler.post(alertRunnable);
-
-        return START_STICKY;
-    }
-
-    private void playAlert() {
-        // Your existing audio playback code goes here
-        if (mediaPlayer == null) {
-            ringtoneUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
-            if (DEBUG) Log.d(tag, "ringtoneUri=" + ringtoneUri.toString());
-            mediaPlayer = MediaPlayer.create(this, ringtoneUri);
-            if (mediaPlayer == null) {
-                if (DEBUG) Log.d(tag, "Media Player is null, trying alarm");
-                ringtoneUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
-                mediaPlayer = MediaPlayer.create(this, ringtoneUri);
+        if (alarmManager != null) {
+            long triggerTime = System.currentTimeMillis() + intervalMs;
+            // Exact alarm ensures it triggers even in Doze mode
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+                alarmManager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, triggerTime, pendingIntent);
+            } else {
+                alarmManager.setExact(AlarmManager.RTC_WAKEUP, triggerTime, pendingIntent);
             }
-            if (mediaPlayer == null) {
-                if (DEBUG) Log.d(tag, "Media Player is null, trying ringtone");
-                ringtoneUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_RINGTONE);
-                mediaPlayer = MediaPlayer.create(this, ringtoneUri);
-            }
-            if (mediaPlayer == null) {
-                if (DEBUG) Log.d(tag, "Media Player is null, trying all");
-                ringtoneUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALL);
-                mediaPlayer = MediaPlayer.create(this, ringtoneUri);
-            }
-            if (mediaPlayer == null) {
-                if (DEBUG) Log.d(tag, "Media Player is null, trying local sound byte");
-                mediaPlayer = MediaPlayer.create(this, R.raw.chime_sound_7143);
-            }
-            mediaPlayer.seekTo(0);
-            mediaPlayer.start();
+            Log.d(TAG, "Alarm set for " + intervalMs + "ms at " + triggerTime);
+        } else {
+            Log.e(TAG, "Could not get AlarmManager service");
         }
     }
 
-    @Override
-    public void onDestroy() {
-        super.onDestroy();
-        handler.removeCallbacks(alertRunnable);
-        if (mediaPlayer != null) {
-            mediaPlayer.release();
-            mediaPlayer = null;
+    /**
+     * Cancels the timer. If the app is killed, alarms are dropped automatically.
+     */
+    public static void stop(Context context) {
+        Intent intent = new Intent(context, TimerReceiver.class);
+        int flags = PendingIntent.FLAG_UPDATE_CURRENT | PendingIntent.FLAG_CANCEL_CURRENT;
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+            flags |= PendingIntent.FLAG_IMMUTABLE;
+        }
+
+        PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, flags);
+        AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
+        
+        if (alarmManager != null) {
+            alarmManager.cancel(pendingIntent);
+            Log.d(TAG, "Alarm cancelled");
         }
     }
 
-    @Override
-    public IBinder onBind(Intent intent) {
-        return null;
+    /**
+     * Checks/Requests permission for exact alarms on Android 12+
+     */
+    public static boolean isExactAlarmAllowed(Context context) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
+            AlarmManager am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
+            return am != null && am.canScheduleExactAlarms();
+        }
+        return true; // Android 11 and below allow exact alarms by default
     }
 
-    private Notification buildNotification() {
-        Intent notificationIntent = new Intent(this, MainActivity.class);
-        PendingIntent pendingIntent = PendingIntent.getActivity(
-                this, 0, notificationIntent,
-                PendingIntent.FLAG_UPDATE_CURRENT | PendingIntent.FLAG_IMMUTABLE
-        );
-
-        return new NotificationCompat.Builder(this, CHANNEL_ID)
-                .setContentTitle("Alert Service Running")
-                .setContentText("Playing alerts at " + intervalMs + "ms intervals")
-                .setSmallIcon(R.drawable.ic_notification)
-                .setOngoing(true)
-                .setContentIntent(pendingIntent)
-                .build();
-    }
-
-    private void createNotificationChannel() {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
-            NotificationChannel channel = new NotificationChannel(
-                    CHANNEL_ID, "Alert Service", NotificationManager.IMPORTANCE_LOW);
-            getSystemService(NotificationManager.class)
-                    .createNotificationChannel(channel);
+    /**
+     * Helper to request exact alarm permission if missing
+     */
+    public static void requestExactAlarmPermission(android.app.Activity activity) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S && !isExactAlarmAllowed(activity)) {
+            Intent intent = new Intent(Settings.ACTION_REQUEST_SCHEDULE_EXACT_ALARM);
+            activity.startActivity(intent);
         }
     }
 }

app/src/main/java/com/hyperling/apps/infinitetimer/MainActivity.java

@@ -5,13 +5,14 @@ import android.content.DialogInterface;
 import android.content.SharedPreferences;
 import android.graphics.Color;
 import android.media.AudioManager;
-import android.media.MediaPlayer;
 import android.media.Ringtone;
 import android.media.RingtoneManager;
 import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
+import android.provider.Settings;
 import android.support.v7.app.AlertDialog;
 import android.support.v7.app.AppCompatActivity;
 import android.util.Log;
@@ -91,48 +92,11 @@ public class MainActivity extends AppCompatActivity {
         if (DEBUG) Log.d(tag, "Got preferences.");
 
         // Sound
-        ringtoneUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
-        if (DEBUG) Log.d(tag, "ringtoneUri=" + ringtoneUri.toString());
-        mediaPlayer = MediaPlayer.create(this, ringtoneUri);
-        if (mediaPlayer == null) {
-            if (DEBUG) Log.d(tag, "Media Player is null, trying alarm");
-            ringtoneUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
-            mediaPlayer = MediaPlayer.create(this, ringtoneUri);
-        }
-        if (mediaPlayer == null) {
-            if (DEBUG) Log.d(tag, "Media Player is null, trying ringtone");
-            ringtoneUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_RINGTONE);
-            mediaPlayer = MediaPlayer.create(this, ringtoneUri);
-        }
-        if (mediaPlayer == null) {
-            if (DEBUG) Log.d(tag, "Media Player is null, trying all");
-            ringtoneUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALL);
-            mediaPlayer = MediaPlayer.create(this, ringtoneUri);
-        }
-        if (mediaPlayer == null) {
-            if (DEBUG) Log.d(tag, "Media Player is null, trying local sound byte");
-            mediaPlayer = MediaPlayer.create(this, R.raw.chime_sound_7143);
-        }
-        if (mediaPlayer == null) {
-            String message = "Could not find a notification, alarm, or ringtone to play.";
-            message += " App will not be able to function without one of these.";
-            message += " Please exit and install a system notification sound.";
-
-            new AlertDialog.Builder(MainActivity.this)
-                .setTitle("Error")
-                .setMessage(message)
-                .setPositiveButton("Exit", new DialogInterface.OnClickListener() {
-                    @Override
-                    public void onClick(DialogInterface dialog, int which) {
-                        dialog.dismiss();
-                        finish();
-                    }
-                })
-                .setCancelable(false)
-                .show()
-            ;
-        } else {
-            if (DEBUG) Log.d(tag, "mediaPlayer=" + mediaPlayer.toString());
+        // Check exact alarm permission for Android 12+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S && !Alert.isExactAlarmAllowed(this)) {
+            if (DEBUG) Log.w(tag, "Exact alarm permission not granted, requesting...");
+            Intent intent = new Intent(Settings.ACTION_REQUEST_SCHEDULE_EXACT_ALARM);
+            startActivity(intent);
         }
 
         if (DEBUG){
@@ -383,6 +347,20 @@ public class MainActivity extends AppCompatActivity {
             setLoopInterval();
             resetTimeLeft();
             setStartTime();
+            
+            // Start the background alert service using Alert manager
+            long interval = longLoopInterval > 1000 ? longLoopInterval : 60000; // Minimum 1 minute interval for alarms
+            if (Alert.isExactAlarmAllowed(this)) {
+                Alert.start(this, interval);
+            } else {
+                if (DEBUG) Log.w(tag, "Cannot start alert: Exact alarm permission denied.");
+                new AlertDialog.Builder(MainActivity.this)
+                    .setTitle("Permission Required")
+                    .setMessage("Please grant 'All files access' or 'Alarm' permissions in system settings for this feature to work.")
+                    .setPositiveButton("OK", (d, w) -> d.dismiss())
+                    .show();
+            }
+
         }
         else if (buttonText.equals(getString(R.string.btnPause))){
             btnStartStop.setText(getString(R.string.btnResume));
@@ -665,6 +643,9 @@ public class MainActivity extends AppCompatActivity {
         String tag = TAG + "resetAll";
         if (DEBUG) Log.d(tag, "Starting");
 
+        // Stop the background alert service when resetting
+        Alert.stop(this);
+
         if (DEBUG) Log.d(tag, "Resetting screen values...");
         setChronometer(0);
         setEditTexts("");
@@ -745,7 +726,8 @@ public class MainActivity extends AppCompatActivity {
         String tag = TAG + "onDestroy";
         if (DEBUG) Log.d(tag, "Starting");
 
-        resetAll();
+        // Stop the background alert service when destroying activity
+        Alert.stop(this);
         
         if (DEBUG) Log.d(tag, "Done with local code, calling super..");
 

app/src/main/java/com/hyperling/apps/infinitetimer/TimerForegroundService.java

@@ -0,0 +1,94 @@
+package com.hyperling.apps.infinitetimer;
+
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.app.Service;
+import android.content.Intent;
+import android.media.MediaPlayer;
+import android.net.Uri;
+import android.os.Build;
+import android.os.IBinder;
+import android.os.PowerManager;
+import android.util.Log;
+
+public class TimerForegroundService extends Service {
+    private static final String TAG = "TimerFGService";
+    private static final String CHANNEL_ID = "timer_notification_channel";
+    private static final int NOTIFICATION_ID = 1001;
+
+    private PowerManager.WakeLock wakeLock;
+    private MediaPlayer mediaPlayer;
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+        createNotificationChannel();
+        
+        // Android 8+ requires foreground service to play sound reliably while backgrounded
+        startForeground(NOTIFICATION_ID, buildNotification());
+        
+        PowerManager pm = (PowerManager) getSystemService(POWER_SERVICE);
+        wakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "TimerWakeLock");
+        // Lock for up to 60 seconds to ensure audio finishes playing even if CPU sleeps
+        wakeLock.acquire(60 * 1000L); 
+        
+        playSound();
+    }
+
+    @Override
+    public int onStartCommand(Intent intent, int flags, int startId) {
+        return START_NOT_STICKY; // Don't restart immediately if killed
+    }
+
+    private void createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            NotificationChannel channel = new NotificationChannel(CHANNEL_ID, "Timer Notifications", NotificationManager.IMPORTANCE_HIGH);
+            // Disable default sound to avoid double-sound on some OEMs
+            channel.setSound(null, null); 
+            channel.enableVibration(false);
+            NotificationManager manager = getSystemService(NotificationManager.class);
+            if (manager != null) manager.createNotificationChannel(channel);
+        }
+    }
+
+    private android.app.Notification buildNotification() {
+        return new android.app.NotificationCompat.Builder(this, CHANNEL_ID)
+                .setContentTitle("Infinite Timer")
+                .setContentText("Timer is active...")
+                // Use system alarm icon temporarily. Add your own ic_stat_notification if desired
+                .setSmallIcon(android.R.drawable.ic_lock_idle_alarm) 
+                .setPriority(android.app.NotificationCompat.PRIORITY_HIGH)
+                .setOngoing(true)
+                .build();
+    }
+
+    private void playSound() {
+        if (mediaPlayer != null && mediaPlayer.isPlaying()) return;
+        
+        try {
+            // Plays default notification sound. Replace with R.raw.your_sound if you want custom audio
+            Uri uri = android.media.RingtoneManager.getDefaultUri(android.media.RingtoneManager.TYPE_NOTIFICATION);
+            mediaPlayer = MediaPlayer.create(this, uri);
+            
+            if (mediaPlayer != null) {
+                mediaPlayer.setOnCompletionListener(mp -> stopSelf()); // Stop immediately after playing
+                mediaPlayer.start();
+            } else {
+                stopSelf(); // Fallback if media player fails
+            }
+        } catch (Exception e) {
+            Log.e(TAG, "Failed to play sound", e);
+            stopSelf();
+        }
+    }
+
+    @Override
+    public IBinder onBind(Intent intent) { return null; }
+
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        if (wakeLock.isHeld()) wakeLock.release();
+        if (mediaPlayer != null) { mediaPlayer.release(); mediaPlayer = null; }
+    }
+}

app/src/main/java/com/hyperling/apps/infinitetimer/TimerReceiver.java

@@ -0,0 +1,20 @@
+package com.hyperling.apps.infinitetimer;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.util.Log;
+
+public class TimerReceiver extends BroadcastReceiver {
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        if (intent.getAction() != null && Alert.ACTION_TIMER.equals(intent.getAction())) {
+            // Android 8+ requires foreground service to play sound reliably while backgrounded
+            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
+                context.startForegroundService(new Intent(context, TimerForegroundService.class));
+            } else {
+                context.startService(new Intent(context, TimerForegroundService.class));
+            }
+        }
+    }
+}