Android Notification Not Showing On API 26

Android Notification Not Showing On API 26 - android

I recently updated my app to API 26, and notifications are no longer working, without even changing the code.
val notification = NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.ic_notification)
.setContentTitle("Title")
.setContentText("Text")
.build()
(getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager).notify(1, notification)
Why isn't it working? Was there some change to the API that I'm not aware of?

From the documentation:
Android O introduces notification channels to provide a unified system to help users manage notifications. When you target Android O, you must implement one or more notification channels to display notifications to your users. If you don't target Android O, your apps behave the same as they do on Android 7.0 when running on Android O devices.
(emphasis added)
You do not seem to be associating this Notification with a channel.

Here i post some quick solution
public void notification(String title, String message, Context context) {
NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
int notificationId = createID();
String channelId = "channel-id";
String channelName = "Channel Name";
int importance = NotificationManager.IMPORTANCE_HIGH;
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
NotificationChannel mChannel = new NotificationChannel(
channelId, channelName, importance);
notificationManager.createNotificationChannel(mChannel);
}
NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context, channelId)
.setSmallIcon(R.drawable.app_logo)//R.mipmap.ic_launcher
.setContentTitle(title)
.setContentText(message)
.setVibrate(new long[]{100, 250})
.setLights(Color.YELLOW, 500, 5000)
.setAutoCancel(true)
.setColor(ContextCompat.getColor(context, R.color.colorPrimary));
TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
stackBuilder.addNextIntent(new Intent(context, MainAcivity.class));
PendingIntent resultPendingIntent = stackBuilder.getPendingIntent(0,PendingIntent.FLAG_UPDATE_CURRENT);
mBuilder.setContentIntent(resultPendingIntent);
notificationManager.notify(notificationId, mBuilder.build());
}
public int createID() {
Date now = new Date();
int id = Integer.parseInt(new SimpleDateFormat("ddHHmmss", Locale.FRENCH).format(now));
return id;
}

Related

Bad notification for startForeground for Android 9 [duplicate]

After upgrading my phone to 8.1 Developer Preview my background service no longer starts up properly.
In my long-running service I've implemented a startForeground method to start the ongoing notification which is called in on create.
#TargetApi(Build.VERSION_CODES.O)
private fun startForeground() {
// Safe call, handled by compat lib.
val notificationBuilder = NotificationCompat.Builder(this, DEFAULT_CHANNEL_ID)
val notification = notificationBuilder.setOngoing(true)
.setSmallIcon(R.drawable.ic_launcher_foreground)
.build()
startForeground(101, notification)
}
Error message:
11-28 11:47:53.349 24704-24704/$PACKAGE_NAMEE/AndroidRuntime: FATAL EXCEPTION: main
Process: $PACKAGE_NAME, PID: 24704
android.app.RemoteServiceException: Bad notification for startForeground: java.lang.RuntimeException: invalid channel for service notification: Notification(channel=My channel pri=0 contentView=null vibrate=null sound=null defaults=0x0 flags=0x42 color=0x00000000 vis=PRIVATE)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1768)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
invalid channel for service notification, apparently my old channel the DEFAULT_CHANNEL_ID is no longer appropriate for API 27 I assume. What would be the proper channel? I've tried to look through the documentation

After some tinkering for a while with different solutions i found out that one must create a notification channel in Android 8.1 and above.
private fun startForeground() {
val channelId =
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
createNotificationChannel("my_service", "My Background Service")
} else {
// If earlier version channel ID is not used
// https://developer.android.com/reference/android/support/v4/app/NotificationCompat.Builder.html#NotificationCompat.Builder(android.content.Context)
""
}
val notificationBuilder = NotificationCompat.Builder(this, channelId )
val notification = notificationBuilder.setOngoing(true)
.setSmallIcon(R.mipmap.ic_launcher)
.setPriority(PRIORITY_MIN)
.setCategory(Notification.CATEGORY_SERVICE)
.build()
startForeground(101, notification)
}
#RequiresApi(Build.VERSION_CODES.O)
private fun createNotificationChannel(channelId: String, channelName: String): String{
val chan = NotificationChannel(channelId,
channelName, NotificationManager.IMPORTANCE_NONE)
chan.lightColor = Color.BLUE
chan.lockscreenVisibility = Notification.VISIBILITY_PRIVATE
val service = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
service.createNotificationChannel(chan)
return channelId
}
From my understanding background services are now displayed as normal notifications that the user then can select to not show by deselecting the notification channel.
Update:
Also don't forget to add the foreground permission as required Android P:
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

Java Solution (Android 9.0, API 28)
In your Service class, add this:
#Override
public void onCreate(){
super.onCreate();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
startMyOwnForeground();
else
startForeground(1, new Notification());
}
private void startMyOwnForeground(){
String NOTIFICATION_CHANNEL_ID = "com.example.simpleapp";
String channelName = "My Background Service";
NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName, NotificationManager.IMPORTANCE_NONE);
chan.setLightColor(Color.BLUE);
chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
assert manager != null;
manager.createNotificationChannel(chan);
NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID);
Notification notification = notificationBuilder.setOngoing(true)
.setSmallIcon(R.drawable.icon_1)
.setContentTitle("App is running in background")
.setPriority(NotificationManager.IMPORTANCE_MIN)
.setCategory(Notification.CATEGORY_SERVICE)
.build();
startForeground(2, notification);
}
UPDATE: ANDROID 9.0 PIE (API 28)
Add this permission to your AndroidManifest.xml file:
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

The first answer is great only for those people who know kotlin, for those who still using java here I translate the first answer
public Notification getNotification() {
String channel;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
channel = createChannel();
else {
channel = "";
}
NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this, channel).setSmallIcon(android.R.drawable.ic_menu_mylocation).setContentTitle("snap map fake location");
Notification notification = mBuilder
.setPriority(PRIORITY_LOW)
.setCategory(Notification.CATEGORY_SERVICE)
.build();
return notification;
}
#NonNull
#TargetApi(26)
private synchronized String createChannel() {
NotificationManager mNotificationManager = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE);
String name = "snap map fake location ";
int importance = NotificationManager.IMPORTANCE_LOW;
NotificationChannel mChannel = new NotificationChannel("snap map channel", name, importance);
mChannel.enableLights(true);
mChannel.setLightColor(Color.BLUE);
if (mNotificationManager != null) {
mNotificationManager.createNotificationChannel(mChannel);
} else {
stopSelf();
}
return "snap map channel";
}
For android, P don't forget to include this permission
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

Works properly on Andorid 8.1:
Updated sample (without any deprecated code):
public NotificationBattery(Context context) {
this.mCtx = context;
mBuilder = new NotificationCompat.Builder(context, CHANNEL_ID)
.setContentTitle(context.getString(R.string.notification_title_battery))
.setSmallIcon(R.drawable.ic_launcher)
.setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
.setChannelId(CHANNEL_ID)
.setOnlyAlertOnce(true)
.setPriority(NotificationCompat.PRIORITY_MAX)
.setWhen(System.currentTimeMillis() + 500)
.setGroup(GROUP)
.setOngoing(true);
mRemoteViews = new RemoteViews(context.getPackageName(), R.layout.notification_view_battery);
initBatteryNotificationIntent();
mBuilder.setContent(mRemoteViews);
mNotificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
if (AesPrefs.getBooleanRes(R.string.SHOW_BATTERY_NOTIFICATION, true)) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationChannel channel = new NotificationChannel(CHANNEL_ID, context.getString(R.string.notification_title_battery),
NotificationManager.IMPORTANCE_DEFAULT);
channel.setShowBadge(false);
channel.setSound(null, null);
mNotificationManager.createNotificationChannel(channel);
}
} else {
mNotificationManager.cancel(Const.NOTIFICATION_CLIPBOARD);
}
}
Old snipped (it's a different app - not related to the code above):
#Override
public int onStartCommand(Intent intent, int flags, final int startId) {
Log.d(TAG, "onStartCommand");
String CHANNEL_ONE_ID = "com.kjtech.app.N1";
String CHANNEL_ONE_NAME = "Channel One";
NotificationChannel notificationChannel = null;
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
notificationChannel = new NotificationChannel(CHANNEL_ONE_ID,
CHANNEL_ONE_NAME, IMPORTANCE_HIGH);
notificationChannel.enableLights(true);
notificationChannel.setLightColor(Color.RED);
notificationChannel.setShowBadge(true);
notificationChannel.setLockscreenVisibility(Notification.VISIBILITY_PUBLIC);
NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
manager.createNotificationChannel(notificationChannel);
}
Bitmap icon = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);
Notification notification = new Notification.Builder(getApplicationContext())
.setChannelId(CHANNEL_ONE_ID)
.setContentTitle(getString(R.string.obd_service_notification_title))
.setContentText(getString(R.string.service_notification_content))
.setSmallIcon(R.mipmap.ic_launcher)
.setLargeIcon(icon)
.build();
Intent notificationIntent = new Intent(getApplicationContext(), MainActivity.class);
notificationIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
notification.contentIntent = PendingIntent.getActivity(getApplicationContext(), 0, notificationIntent, 0);
startForeground(START_FOREGROUND_ID, notification);
return START_STICKY;
}

In my case, it's because we tried to post a notification without specifying the NotificationChannel:
public static final String NOTIFICATION_CHANNEL_ID_SERVICE = "com.mypackage.service";
public static final String NOTIFICATION_CHANNEL_ID_TASK = "com.mypackage.download_info";
public void initChannel(){
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
nm.createNotificationChannel(new NotificationChannel(NOTIFICATION_CHANNEL_ID_SERVICE, "App Service", NotificationManager.IMPORTANCE_DEFAULT));
nm.createNotificationChannel(new NotificationChannel(NOTIFICATION_CHANNEL_ID_INFO, "Download Info", NotificationManager.IMPORTANCE_DEFAULT));
}
}
The best place to put above code is in onCreate() method in the Application class, so that we just need to declare it once for all:
public class App extends Application {
#Override
public void onCreate() {
super.onCreate();
initChannel();
}
}
After we set this up, we can use notification with the channelId we just specified:
Intent i = new Intent(this, MainActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
PendingIntent pi = PendingIntent.getActivity(this, 0, i, PendingIntent.FLAG_UPDATE_CURRENT);
NotificationCompat.Builder builder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID_INFO);
.setContentIntent(pi)
.setWhen(System.currentTimeMillis())
.setContentTitle("VirtualBox.exe")
.setContentText("Download completed")
.setSmallIcon(R.mipmap.ic_launcher);
Then, we can use it to post a notification:
int notifId = 45;
NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
nm.notify(notifId, builder.build());
If you want to use it as foreground service's notification:
startForeground(notifId, builder.build());

Thanks to #CopsOnRoad, his solution was a big help but only works for SDK
26 and higher. My app targets 24 and higher.
To keep Android Studio from complaining you need a conditional directly around the notification. It is not smart enough to know the code is in a method conditional to VERSION_CODE.O.
#Override
public void onCreate(){
super.onCreate();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
startMyOwnForeground();
else
startForeground(1, new Notification());
}
private void startMyOwnForeground(){
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O){
String NOTIFICATION_CHANNEL_ID = "com.example.simpleapp";
String channelName = "My Background Service";
NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName, NotificationManager.IMPORTANCE_NONE);
chan.setLightColor(Color.BLUE);
chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
assert manager != null;
manager.createNotificationChannel(chan);
NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID);
Notification notification = notificationBuilder.setOngoing(true)
.setSmallIcon(AppSpecific.SMALL_ICON)
.setContentTitle("App is running in background")
.setPriority(NotificationManager.IMPORTANCE_MIN)
.setCategory(Notification.CATEGORY_SERVICE)
.build();
startForeground(2, notification);
}
}

This worked for me. In my service class, I created the notification channel for android 8.1 as below:
public class Service extends Service {
public static final String NOTIFICATION_CHANNEL_ID_SERVICE = "com.package.MyService";
public static final String NOTIFICATION_CHANNEL_ID_INFO = "com.package.download_info";
#Override
public void onCreate() {
super.onCreate();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
nm.createNotificationChannel(new NotificationChannel(NOTIFICATION_CHANNEL_ID_SERVICE, "App Service", NotificationManager.IMPORTANCE_DEFAULT));
nm.createNotificationChannel(new NotificationChannel(NOTIFICATION_CHANNEL_ID_INFO, "Download Info", NotificationManager.IMPORTANCE_DEFAULT));
} else {
Notification notification = new Notification();
startForeground(1, notification);
}
}
}
Note: Create the channel where you are creating the Notification for Build.VERSION.SDK_INT >= Build.VERSION_CODES.O

Alternative answer: if it's a Huawei device and you have implemented requirements needed for Oreo 8 Android and there are still issues only with Huawei devices than it's only device issue, you can read https://dontkillmyapp.com/huawei

I had the same issue. The problem occurred when I used same channel id and notification id for two apps. So try with a unique notification id and channel id.

this maybe old but, incase someone had the same situation as I did.
for some reason, on Android 11 OnePlus Nord
Notification.Builder().Build()
crashes,
NotificationCompat.Builder().Build()
works fine.
Consider migrating to androidx.core.app.NotificationCompat.

If you're working with VPN library, these code will be help, I placed this inside onCreate(savedInstanceState: Bundle?)
NotificationChannelManager.createNotificationChannelIfNeeded(
activity,
channelName = "Chanel Name",
channelDescription = "Channel description"
)

Here is my solution
private static final int NOTIFICATION_ID = 200;
private static final String CHANNEL_ID = "myChannel";
private static final String CHANNEL_NAME = "myChannelName";
private void startForeground() {
final NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(
getApplicationContext(), CHANNEL_ID);
Notification notification;
notification = mBuilder.setTicker(getString(R.string.app_name)).setWhen(0)
.setOngoing(true)
.setContentTitle(getString(R.string.app_name))
.setContentText("Send SMS gateway is running background")
.setSmallIcon(R.mipmap.ic_launcher)
.setShowWhen(true)
.build();
NotificationManager notificationManager = (NotificationManager) getApplication().getSystemService(Context.NOTIFICATION_SERVICE);
//All notifications should go through NotificationChannel on Android 26 & above
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationChannel channel = new NotificationChannel(CHANNEL_ID,
CHANNEL_NAME,
NotificationManager.IMPORTANCE_DEFAULT);
notificationManager.createNotificationChannel(channel);
}
notificationManager.notify(NOTIFICATION_ID, notification);
}
Hope it will help :)

Notifications always making sound: setSound(null) is not wroking on OS >= 8

I am trying to group notifications and trigger sounds only for some of them using notification builder setSound() method, but it doesn't work. Each time I receive notifications it triggers the ringtone even though I call setSound(null)
This is my code:
TaskStackBuilder stackBuilder = TaskStackBuilder.create(getContext());
stackBuilder.addParentStack(getParentActivityClass());
Intent notificationIntent = intent == null ? new Intent() : new Intent(intent);
if (cls != null)
notificationIntent.setClass(getContext(), cls);
notificationIntent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
stackBuilder.addNextIntentWithParentStack(notificationIntent);
PendingIntent pendingIntent = stackBuilder.getPendingIntent(0,
PendingIntent.FLAG_UPDATE_CURRENT);
InboxStyle style = new NotificationCompat.InboxStyle();
int mapId = subGroupId + groupId;
putGroupLine(mapId, text);
List<String> notifLines = groupedNotificationsMap.get(mapId);
for (int i = 0; i < notifLines.size(); i++) {
style.addLine(notifLines.get(i));
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
String NOTIFICATION_CHANNEL_ID = "default";
String channelName = "Default";
NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName
, NotificationManager.IMPORTANCE_HIGH);
chan.setLightColor(Color.BLUE);
chan.setLockscreenVisibility(Notification.VISIBILITY_PUBLIC);
if (alert == false) {
chan.setSound(null, null);
chan.setVibrationPattern(null);
}
else {
chan.setVibrationPattern(vibrate);
}
NotificationManager manager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
manager.createNotificationChannel(chan);
}
NotificationCompat.Builder mBuilder;
mBuilder = new NotificationCompat.Builder(context, "default")
.setSmallIcon(getSmallIconResource())
.setAutoCancel(true);
int colorRes = getSmallIconColor();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
mBuilder.setGroupAlertBehavior(NotificationCompat.GROUP_ALERT_SUMMARY);
}
if (alert) {
mBuilder.setSound(getRingtone());
mBuilder.setVibrate( vibrate );
}
else {
mBuilder.setSound(null);
mBuilder.setVibrate(null);
}
Notification notif = mBuilder
.setContentTitle(title)
.setTicker(text)
.setContentText(text)
.setSmallIcon(getSmallIconResource())
.setStyle(style
.setBigContentTitle(title)
)
.setGroup("g" + groupId)
.setContentIntent(pendingIntent)
.build();
NotificationCompat.Builder summaryBiulder = new NotificationCompat.Builder(getContext(), "default")
.setContentTitle(title)
.setAutoCancel(true)
//set content text to support devices running API level < 24
.setContentText(text)
.setSmallIcon(getSmallIconResource())
//build summary info into InboxStyle template
.setStyle(new InboxStyle()
.setBigContentTitle(title)
.setSummaryText(title))
.setColor(colorRes)
//specify which group this notification belongs to
.setGroup("g" + groupId)
//set this notification as the summary for the group
.setGroupSummary(true)
.setGroupAlertBehavior(NotificationCompat.GROUP_ALERT_SUMMARY)
.setContentIntent(pendingIntent);
if (alert) {
summaryBiulder.setSound(getRingtone());
summaryBiulder.setVibrate( vibrate );
}
else {
summaryBiulder.setSound(null);
summaryBiulder.setVibrate(null);
}
Notification summaryNotification = summaryBiulder .build();
notif.flags |= Notification.FLAG_AUTO_CANCEL;
notif.flags |= Notification.FLAG_HIGH_PRIORITY;
notifManager.notify(subGroupId, notif);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
notifManager.notify(groupId, summaryNotification);
}
Any suggestions?

Your problem is about notification importance
importance types
IMPORTANCE_MAX: unused
IMPORTANCE_HIGH: shows everywhere, makes noise and peeks
IMPORTANCE_DEFAULT: shows everywhere, makes noise, but does not visually intrude
IMPORTANCE_LOW: shows everywhere, but is not intrusive
IMPORTANCE_MIN: only shows in the shade, below the fold
IMPORTANCE_NONE: a notification with no importance; does not show in the shade
source

Although the other answers are useful, the main issue here was that the notification channel was already created. So, as stated in the docs, the behavior of a channel cannot be changed after creation (sound and vibration in this case). Only name and description can be changed, the user has full control over the rest.

In the code snippet,
NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName,
NotificationManager.IMPORTANCE_HIGH);
Try replacing
NotificationManager.IMPORTANCE_HIGH to NotificationManager.IMPORTANCE_NONE
As according to Android developer documentation,
IMPORTANCE_HIGH
Higher notification importance: shows everywhere, makes noise and peeks. May use full screen intents.
So it may be making sound due to this.
Here's the link to other importance values available

Android 8 (Oreo) notification not showing up

Intent intent = new Intent(this, SplashActivity.class);
Bundle bundle = new Bundle();
bundle.putString("splash", psd);
bundle.putString("targetId", targetId);
intent.putExtras(bundle);
intent.setAction(psd);
intent.setAction(targetId);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK);
PendingIntent pendingIntent = PendingIntent.getActivity(getApplicationContext(), id, intent,
0);
Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
.setSmallIcon(android.R.drawable.ic_notification_overlay)
.setContentTitle(title)
.setContentText(remoteMessage.getData().get("body"))
.setAutoCancel(true)
.setStyle(new NotificationCompat.BigTextStyle().bigText("" + remoteMessage.getData().get("body")))
.setContentIntent(pendingIntent)
.setSound(defaultSoundUri);
NotificationCompat.InboxStyle inboxStyle =
new NotificationCompat.InboxStyle();
String[] events = new String[6];
inboxStyle.setBigContentTitle("" + title);
for (int i = 0; i < events.length; i++) {
inboxStyle.addLine(events[i]);
}
//.setContentIntent(pendingIntent);
NotificationManager notificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
notificationManager.notify(id, notificationBuilder.build());
It used to be working, no clue what's happening on new Android devices like Android O. I didn't try back going to old devices, but it's happening on pixel.

Starting in Android 8.0 (API level 26), all notifications must be
assigned to a channel. For each channel, you can set the visual and
auditory behavior that is applied to all notifications in that
channel. Then, users can change these settings and decide which
notification channels from your app should be intrusive or visible at
all
Notification channels

try this code it works perfectly for me.
Uri soundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
PendingIntent resultPendingIntent = PendingIntent.getActivity(this, 0, resultIntent, PendingIntent.FLAG_CANCEL_CURRENT);
NotificationCompat.InboxStyle inboxStyle = new NotificationCompat.InboxStyle();
inboxStyle.addLine(message);
NotificationManager mNotificationManager = (NotificationManager) getApplicationContext().getSystemService(Context.NOTIFICATION_SERVICE);
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(getApplicationContext(),"channel_01")
.setSmallIcon(R.mipmap.ic_launcher)
.setContentText(message)
.setContentIntent(resultPendingIntent)
.setAutoCancel(true)
.setPriority(Notification.PRIORITY_HIGH)
.setChannelId("channel_01")
.setSound(RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION))
.setStyle(inboxStyle)
.setContentTitle(Title);
mNotificationManager.notify(Notification_ID, mBuilder.build());
NotificationChannel channel = new NotificationChannel(Notification_ID, "Playback Notification", NotificationManager.IMPORTANCE_HIGH);
channel.enableLights(true);
channel.enableVibration(true);
channel.setVibrationPattern(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 400});
assert mNotificationManager != null;
mBuilder.setChannelId("channel_01");
mNotificationManager.createNotificationChannel(channel);
}else {
NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(getApplicationContext(),Notification_ID)
.setSmallIcon(R.mipmap.ic_launcher)
.setContentTitle(Title)
.setContentIntent(resultPendingIntent)
.setContentText(message)
.setStyle(inboxStyle)
.setSound(soundUri)
.setAutoCancel(true);
mNotificationManager.notify(Notification_ID, mBuilder.build());
}

I just figured this one out myself, you need to setup Channels in Oreo, see my previous post on the issue - I though it was a master-detail issue!!! Turns out Oreo has an additional attribute you need but it seems to fail silently if you don't provide it.

Set up notification channels. Example code below
public static void createNotificationChannel(final Context context, final
String channelId, final CharSequence channelName, final String channelDescription, final int importance, final boolean showBadge) {
try {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
postAsyncSafely("createNotificationChannel", new Runnable() {
#Override
public void run() {
NotificationManager notificationManager = (NotificationManager) context.getSystemService(NOTIFICATION_SERVICE);
NotificationChannel notificationChannel = new NotificationChannel(channelId, channelName, importance);
notificationChannel.setDescription(channelDescription);
notificationChannel.setShowBadge(showBadge);
notificationManager.createNotificationChannel(notificationChannel);
Logger.i("Notification channel " + channelName.toString() +
" has been created");
}
});
}
}catch (Throwable t){
Logger.v("Failure creating Notification Channel",t);
}
}

startForeground fail after upgrade to Android 8.1

After upgrading my phone to 8.1 Developer Preview my background service no longer starts up properly.
In my long-running service I've implemented a startForeground method to start the ongoing notification which is called in on create.
#TargetApi(Build.VERSION_CODES.O)
private fun startForeground() {
// Safe call, handled by compat lib.
val notificationBuilder = NotificationCompat.Builder(this, DEFAULT_CHANNEL_ID)
val notification = notificationBuilder.setOngoing(true)
.setSmallIcon(R.drawable.ic_launcher_foreground)
.build()
startForeground(101, notification)
}
Error message:
11-28 11:47:53.349 24704-24704/$PACKAGE_NAMEE/AndroidRuntime: FATAL EXCEPTION: main
Process: $PACKAGE_NAME, PID: 24704
android.app.RemoteServiceException: Bad notification for startForeground: java.lang.RuntimeException: invalid channel for service notification: Notification(channel=My channel pri=0 contentView=null vibrate=null sound=null defaults=0x0 flags=0x42 color=0x00000000 vis=PRIVATE)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1768)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
invalid channel for service notification, apparently my old channel the DEFAULT_CHANNEL_ID is no longer appropriate for API 27 I assume. What would be the proper channel? I've tried to look through the documentation

After some tinkering for a while with different solutions i found out that one must create a notification channel in Android 8.1 and above.
private fun startForeground() {
val channelId =
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
createNotificationChannel("my_service", "My Background Service")
} else {
// If earlier version channel ID is not used
// https://developer.android.com/reference/android/support/v4/app/NotificationCompat.Builder.html#NotificationCompat.Builder(android.content.Context)
""
}
val notificationBuilder = NotificationCompat.Builder(this, channelId )
val notification = notificationBuilder.setOngoing(true)
.setSmallIcon(R.mipmap.ic_launcher)
.setPriority(PRIORITY_MIN)
.setCategory(Notification.CATEGORY_SERVICE)
.build()
startForeground(101, notification)
}
#RequiresApi(Build.VERSION_CODES.O)
private fun createNotificationChannel(channelId: String, channelName: String): String{
val chan = NotificationChannel(channelId,
channelName, NotificationManager.IMPORTANCE_NONE)
chan.lightColor = Color.BLUE
chan.lockscreenVisibility = Notification.VISIBILITY_PRIVATE
val service = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
service.createNotificationChannel(chan)
return channelId
}
From my understanding background services are now displayed as normal notifications that the user then can select to not show by deselecting the notification channel.
Update:
Also don't forget to add the foreground permission as required Android P:
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

Java Solution (Android 9.0, API 28)
In your Service class, add this:
#Override
public void onCreate(){
super.onCreate();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
startMyOwnForeground();
else
startForeground(1, new Notification());
}
private void startMyOwnForeground(){
String NOTIFICATION_CHANNEL_ID = "com.example.simpleapp";
String channelName = "My Background Service";
NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName, NotificationManager.IMPORTANCE_NONE);
chan.setLightColor(Color.BLUE);
chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
assert manager != null;
manager.createNotificationChannel(chan);
NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID);
Notification notification = notificationBuilder.setOngoing(true)
.setSmallIcon(R.drawable.icon_1)
.setContentTitle("App is running in background")
.setPriority(NotificationManager.IMPORTANCE_MIN)
.setCategory(Notification.CATEGORY_SERVICE)
.build();
startForeground(2, notification);
}
UPDATE: ANDROID 9.0 PIE (API 28)
Add this permission to your AndroidManifest.xml file:
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

The first answer is great only for those people who know kotlin, for those who still using java here I translate the first answer
public Notification getNotification() {
String channel;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
channel = createChannel();
else {
channel = "";
}
NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this, channel).setSmallIcon(android.R.drawable.ic_menu_mylocation).setContentTitle("snap map fake location");
Notification notification = mBuilder
.setPriority(PRIORITY_LOW)
.setCategory(Notification.CATEGORY_SERVICE)
.build();
return notification;
}
#NonNull
#TargetApi(26)
private synchronized String createChannel() {
NotificationManager mNotificationManager = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE);
String name = "snap map fake location ";
int importance = NotificationManager.IMPORTANCE_LOW;
NotificationChannel mChannel = new NotificationChannel("snap map channel", name, importance);
mChannel.enableLights(true);
mChannel.setLightColor(Color.BLUE);
if (mNotificationManager != null) {
mNotificationManager.createNotificationChannel(mChannel);
} else {
stopSelf();
}
return "snap map channel";
}
For android, P don't forget to include this permission
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

Works properly on Andorid 8.1:
Updated sample (without any deprecated code):
public NotificationBattery(Context context) {
this.mCtx = context;
mBuilder = new NotificationCompat.Builder(context, CHANNEL_ID)
.setContentTitle(context.getString(R.string.notification_title_battery))
.setSmallIcon(R.drawable.ic_launcher)
.setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
.setChannelId(CHANNEL_ID)
.setOnlyAlertOnce(true)
.setPriority(NotificationCompat.PRIORITY_MAX)
.setWhen(System.currentTimeMillis() + 500)
.setGroup(GROUP)
.setOngoing(true);
mRemoteViews = new RemoteViews(context.getPackageName(), R.layout.notification_view_battery);
initBatteryNotificationIntent();
mBuilder.setContent(mRemoteViews);
mNotificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
if (AesPrefs.getBooleanRes(R.string.SHOW_BATTERY_NOTIFICATION, true)) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationChannel channel = new NotificationChannel(CHANNEL_ID, context.getString(R.string.notification_title_battery),
NotificationManager.IMPORTANCE_DEFAULT);
channel.setShowBadge(false);
channel.setSound(null, null);
mNotificationManager.createNotificationChannel(channel);
}
} else {
mNotificationManager.cancel(Const.NOTIFICATION_CLIPBOARD);
}
}
Old snipped (it's a different app - not related to the code above):
#Override
public int onStartCommand(Intent intent, int flags, final int startId) {
Log.d(TAG, "onStartCommand");
String CHANNEL_ONE_ID = "com.kjtech.app.N1";
String CHANNEL_ONE_NAME = "Channel One";
NotificationChannel notificationChannel = null;
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
notificationChannel = new NotificationChannel(CHANNEL_ONE_ID,
CHANNEL_ONE_NAME, IMPORTANCE_HIGH);
notificationChannel.enableLights(true);
notificationChannel.setLightColor(Color.RED);
notificationChannel.setShowBadge(true);
notificationChannel.setLockscreenVisibility(Notification.VISIBILITY_PUBLIC);
NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
manager.createNotificationChannel(notificationChannel);
}
Bitmap icon = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);
Notification notification = new Notification.Builder(getApplicationContext())
.setChannelId(CHANNEL_ONE_ID)
.setContentTitle(getString(R.string.obd_service_notification_title))
.setContentText(getString(R.string.service_notification_content))
.setSmallIcon(R.mipmap.ic_launcher)
.setLargeIcon(icon)
.build();
Intent notificationIntent = new Intent(getApplicationContext(), MainActivity.class);
notificationIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
notification.contentIntent = PendingIntent.getActivity(getApplicationContext(), 0, notificationIntent, 0);
startForeground(START_FOREGROUND_ID, notification);
return START_STICKY;
}

In my case, it's because we tried to post a notification without specifying the NotificationChannel:
public static final String NOTIFICATION_CHANNEL_ID_SERVICE = "com.mypackage.service";
public static final String NOTIFICATION_CHANNEL_ID_TASK = "com.mypackage.download_info";
public void initChannel(){
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
nm.createNotificationChannel(new NotificationChannel(NOTIFICATION_CHANNEL_ID_SERVICE, "App Service", NotificationManager.IMPORTANCE_DEFAULT));
nm.createNotificationChannel(new NotificationChannel(NOTIFICATION_CHANNEL_ID_INFO, "Download Info", NotificationManager.IMPORTANCE_DEFAULT));
}
}
The best place to put above code is in onCreate() method in the Application class, so that we just need to declare it once for all:
public class App extends Application {
#Override
public void onCreate() {
super.onCreate();
initChannel();
}
}
After we set this up, we can use notification with the channelId we just specified:
Intent i = new Intent(this, MainActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
PendingIntent pi = PendingIntent.getActivity(this, 0, i, PendingIntent.FLAG_UPDATE_CURRENT);
NotificationCompat.Builder builder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID_INFO);
.setContentIntent(pi)
.setWhen(System.currentTimeMillis())
.setContentTitle("VirtualBox.exe")
.setContentText("Download completed")
.setSmallIcon(R.mipmap.ic_launcher);
Then, we can use it to post a notification:
int notifId = 45;
NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
nm.notify(notifId, builder.build());
If you want to use it as foreground service's notification:
startForeground(notifId, builder.build());

Thanks to #CopsOnRoad, his solution was a big help but only works for SDK
26 and higher. My app targets 24 and higher.
To keep Android Studio from complaining you need a conditional directly around the notification. It is not smart enough to know the code is in a method conditional to VERSION_CODE.O.
#Override
public void onCreate(){
super.onCreate();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
startMyOwnForeground();
else
startForeground(1, new Notification());
}
private void startMyOwnForeground(){
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O){
String NOTIFICATION_CHANNEL_ID = "com.example.simpleapp";
String channelName = "My Background Service";
NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName, NotificationManager.IMPORTANCE_NONE);
chan.setLightColor(Color.BLUE);
chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
assert manager != null;
manager.createNotificationChannel(chan);
NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID);
Notification notification = notificationBuilder.setOngoing(true)
.setSmallIcon(AppSpecific.SMALL_ICON)
.setContentTitle("App is running in background")
.setPriority(NotificationManager.IMPORTANCE_MIN)
.setCategory(Notification.CATEGORY_SERVICE)
.build();
startForeground(2, notification);
}
}

This worked for me. In my service class, I created the notification channel for android 8.1 as below:
public class Service extends Service {
public static final String NOTIFICATION_CHANNEL_ID_SERVICE = "com.package.MyService";
public static final String NOTIFICATION_CHANNEL_ID_INFO = "com.package.download_info";
#Override
public void onCreate() {
super.onCreate();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
nm.createNotificationChannel(new NotificationChannel(NOTIFICATION_CHANNEL_ID_SERVICE, "App Service", NotificationManager.IMPORTANCE_DEFAULT));
nm.createNotificationChannel(new NotificationChannel(NOTIFICATION_CHANNEL_ID_INFO, "Download Info", NotificationManager.IMPORTANCE_DEFAULT));
} else {
Notification notification = new Notification();
startForeground(1, notification);
}
}
}
Note: Create the channel where you are creating the Notification for Build.VERSION.SDK_INT >= Build.VERSION_CODES.O

Alternative answer: if it's a Huawei device and you have implemented requirements needed for Oreo 8 Android and there are still issues only with Huawei devices than it's only device issue, you can read https://dontkillmyapp.com/huawei

I had the same issue. The problem occurred when I used same channel id and notification id for two apps. So try with a unique notification id and channel id.

this maybe old but, incase someone had the same situation as I did.
for some reason, on Android 11 OnePlus Nord
Notification.Builder().Build()
crashes,
NotificationCompat.Builder().Build()
works fine.
Consider migrating to androidx.core.app.NotificationCompat.

If you're working with VPN library, these code will be help, I placed this inside onCreate(savedInstanceState: Bundle?)
NotificationChannelManager.createNotificationChannelIfNeeded(
activity,
channelName = "Chanel Name",
channelDescription = "Channel description"
)

Here is my solution
private static final int NOTIFICATION_ID = 200;
private static final String CHANNEL_ID = "myChannel";
private static final String CHANNEL_NAME = "myChannelName";
private void startForeground() {
final NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(
getApplicationContext(), CHANNEL_ID);
Notification notification;
notification = mBuilder.setTicker(getString(R.string.app_name)).setWhen(0)
.setOngoing(true)
.setContentTitle(getString(R.string.app_name))
.setContentText("Send SMS gateway is running background")
.setSmallIcon(R.mipmap.ic_launcher)
.setShowWhen(true)
.build();
NotificationManager notificationManager = (NotificationManager) getApplication().getSystemService(Context.NOTIFICATION_SERVICE);
//All notifications should go through NotificationChannel on Android 26 & above
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationChannel channel = new NotificationChannel(CHANNEL_ID,
CHANNEL_NAME,
NotificationManager.IMPORTANCE_DEFAULT);
notificationManager.createNotificationChannel(channel);
}
notificationManager.notify(NOTIFICATION_ID, notification);
}
Hope it will help :)

Android O reporting notification not posted to channel - but it is

Couple Android O notification questions:
1) I have created a Notification Channel (see below), am calling the builder with .setChannelId() (passing in the name of the channel I created, "wakey"; and yet, when I run the app, I get a message that I've failed to post a notification to channel "null". What might be causing this?
2) I suspect the answer to #1 can be found in the "log" that it says to check, but I've checked logcat & don't see anything about notifications or channels. Where is the log that it says to look in?
Here's the code I'm using to create the channel:
NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
CharSequence name = context.getString(R.string.app_name);
String description = "yadda yadda"
int importance = NotificationManager.IMPORTANCE_DEFAULT;
NotificationChannel channel = new NotificationChannel(NOTIFICATION_CHANNEL, name, importance);
channel.setDescription(description);
notificationManager.createNotificationChannel(channel);
Here's the code to generate the notification:
Notification.Builder notificationBuilder;
Intent notificationIntent = new Intent(context, BulbActivity.class);
notificationIntent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND); // Fix for https://code.google.com/p/android/issues/detail?id=53313
PendingIntent contentIntent = PendingIntent.getActivity(context, 0, notificationIntent, 0);
Intent serviceIntent = new Intent(context, RemoteViewToggleService.class);
serviceIntent.putExtra(WakeyService.KEY_REQUEST_SOURCE, WakeyService.REQUEST_SOURCE_NOTIFICATION);
PendingIntent actionPendingIntent = PendingIntent.getService(context, 0, serviceIntent, PendingIntent.FLAG_CANCEL_CURRENT);
_toggleAction = new Notification.Action(R.drawable.ic_power_settings_new_black_24dp, context.getString(R.string.toggle_wakey), actionPendingIntent);
notificationBuilder= new Notification.Builder(context)
.setContentTitle(context.getString(R.string.app_name))
.setContentIntent(contentIntent)
.addAction(_toggleAction);
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
notificationBuilder.setChannelId(NOTIFICATION_CHANNEL);
}
notificationBuilder.setSmallIcon(icon);
notificationBuilder.setContentText(contentText);
_toggleAction.title = actionText;
int priority = getNotificationPriority(context);
notificationBuilder.setPriority(priority);
notificationBuilder.setOngoing(true);
Notification notification = notificationBuilder.build();
notificationManager.notify(NOTIFICATION_ID, notification);
And here's the warning I'm getting:

I think I have learned a couple things that all add up to an answer:
I was using an emulator device, with an image that did not include the Play Store.
The version of Google Play Services on the image was not the latest, so I should have been getting a notification telling me I needed to upgrade. Since that notification didn't get applied to a channel, it didn't appear.
If I set logcat in Android Studio to "No Filters" instead of "Show only selected application", then I found the logs that pointed out that the notification in question was the Play Services "update needed" notification.
So, I changed to a image with the Play Store included, and it showed the notification properly (maybe the channel for that notification was to be set by the Play Store?), let me update to the latest Google Play Services, and I haven't seen that warning since.
So, long story short (too late) - with Android O, if you are using Google Play Services & testing on the emulator, choose an image with the Play Store included, or ignore the toast (good luck on that one!).

I had the same problem, and resolved it by using the constructor
new Notification.Builder(Context context, String channelId), instead of the one which is deprecated onAPI levels >=26 (Android O) :
new NotificationCompat.Builder(Context context)
The following code won't work if your notificationBuilder is built using the deprecated constructor :
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
notificationBuilder.setChannelId(NOTIFICATION_CHANNEL);}

First create the notification channel:
public static final String NOTIFICATION_CHANNEL_ID = "4565";
//Notification Channel
CharSequence channelName = NOTIFICATION_CHANNEL_NAME;
int importance = NotificationManager.IMPORTANCE_LOW;
NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID, NOTIFICATION_CHANNEL_NAME, importance);
notificationChannel.enableLights(true);
notificationChannel.setLightColor(Color.RED);
notificationChannel.enableVibration(true);
notificationChannel.setVibrationPattern(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 400});
NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
notificationManager.createNotificationChannel(notificationChannel);
then use the channel id in the constructor:
final NotificationCompat.Builder builder = new NotificationCompat.Builder(context, NOTIFICATION_CHANNEL_ID)
.setDefaults(Notification.DEFAULT_ALL)
.setSmallIcon(R.drawable.ic_timers)
.setVibrate(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 400})
.setSound(null)
.setChannelId(NOTIFICATION_CHANNEL_ID)
.setContent(contentView)
.setPriority(NotificationCompat.PRIORITY_DEFAULT)
.setLargeIcon(picture)
.setTicker(sTimer)
.setContentIntent(pendingIntent)
.setAutoCancel(false);

You gotta create a channel before.
private void createNotificationChannel() {
// Create the NotificationChannel, but only on API 26+ because
// the NotificationChannel class is new and not in the support library
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
CharSequence name = getString(R.string.channel_name);
String description = getString(R.string.channel_description);
int importance = NotificationManager.IMPORTANCE_DEFAULT;
NotificationChannel channel = new NotificationChannel(CHANNEL_ID, name, importance);
channel.setDescription(description);
// Register the channel with the system; you can't change the importance
// or other notification behaviors after this
NotificationManager notificationManager = getSystemService(NotificationManager.class);
notificationManager.createNotificationChannel(channel);
}
}
public void notifyThis(String title, String message) {
NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this, CHANNEL_ID)
.setSmallIcon(R.drawable.green_circle)
.setContentTitle(title)
.setContentText(message)
.setPriority(NotificationCompat.PRIORITY_DEFAULT);
NotificationManagerCompat notificationManager = NotificationManagerCompat.from(this);
// notificationId is a unique int for each notification that you must define
notificationManager.notify(0, mBuilder.build());
}
Finally you call this method:
createNotificationChannel();
notifyThis("My notification", "Hello World!");

create a notification using following code :
Notification notification = new Notification.Builder(MainActivity.this)
.setContentTitle("New Message")
.setContentText("You've received new messages.")
.setSmallIcon(R.mipmap.ic_launcher)
.setChannelId(channelId)
.build();
not using :
Notification notification = new NotificationCompat.Builder(MainActivity.this)
.setContentTitle("Some Message")
.setContentText("You've received new messages!")
.setSmallIcon(R.mipmap.ic_launcher)
.setChannel(channelId)
.build();

You have to create a NotificationChannel first
val notificationChannel = NotificationChannel("channelId", "channelName", NotificationManager.IMPORTANCE_DEFAULT)
notificationManager.createNotificationChannel(notificationChannel);
This is the only way to show notification for API 26+

I was facing the same problem. It got resolved by creating a NotificationChannel and adding that newly created channel with the notification manager.

I would also like to add that you will receive this error if you're using Build tools v26+:
app/build.grade:
compileSdkVersion 26
buildToolsVersion "26.0.2"
defaultConfig {
targetSdkVersion 26
Downgrading to lowest version should work fine.

Develop Reference

The Android operating system is a mobile operating system that was developed by Google (GOOGL?) to be primarily used for touchscreen devices, cell phones, and tablets.

Android Notification Not Showing On API 26 - android

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Android O reporting notification not posted to channel - but it is

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