Develop Reference

NotificationManager.notify does not create a notification in one app, despite the exact same coding working in another app

I am simultaneously developing two Android applications that are communicating with each other, and I am using notifications to show received messages. This is the code I am using to show a notification:
private void showNotification(String title, String content) {
NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
NotificationChannel channel = new NotificationChannel("default",
"NOTIF_CHANNEL",
NotificationManager.IMPORTANCE_DEFAULT);
channel.setDescription("CHANNEL FOR INFORMING ABOUT MESSAGE RECEIVED");
mNotificationManager.createNotificationChannel(channel);
}
NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(getApplicationContext(), "default")
.setSmallIcon(R.mipmap.ic_launcher) // notification icon
.setContentTitle(title) // title for notification
.setContentText(content)// message for notification
.setSound(Settings.System.DEFAULT_NOTIFICATION_URI) // set alarm sound for notification
.setAutoCancel(true); // clear notification after click
Intent intent = getPackageManager()
.getLaunchIntentForPackage(getPackageName())
.setPackage(null)
.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED);
PendingIntent pi = PendingIntent.getActivity(this, 0, intent, 0);
mBuilder.setContentIntent(pi);
mNotificationManager.notify(0, mBuilder.build());
}
In one of my applications, this works flawlessly every time, but in the other it never works. I am using the exact same code and running the applications on the same device.
I am curious as to if someone is able to identify or make a guess on factors that would make a difference here. I have tried using the same icon, title, content, and sound, but to no avail. Any help or suggestions would be greatly appreciated!

If your code is working in one app but not in the other, and the code is exactly the same, surely you are using distinct versions of support library and/or distinct targetSdkVersion. Set the same of the app which works in the other that doesn't works.

Why my Android notification's setTicker doesn't work?

my code is below:
NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
Notification notification = new NotificationCompat.Builder(MainActivity.this)
.setContentTitle("nothing")
.setContentText("nothing").setWhen(System.currentTimeMillis())
.setSmallIcon(R.mipmap.ic_launcher)
.setTicker("help help help:)")
.setContentInfo("nothing")
.build();
manager.notify(1, notification);
When I run this, "help help help:)" didn't appear.

TickerText will only appear on phone before Android 5.0 (L)
Extracted from Documentation :
Text that summarizes this notification for accessibility services. As
of the L release, this text is no longer shown on screen, but it is
still useful to accessibility services (where it serves as an audible
announcement of the notification's appearance).
https://developer.android.com/reference/android/app/Notification.html#tickerText

Android heads-up notification not showing

I am trying to make heads-up notification work. Notification is created, but it's not displayed at the top of the app.
Here's the code responsible for building a notification:
Notification notification = new NotificationCompat.Builder(context)
.setSmallIcon(android.R.drawable.arrow_up_float)
.setContentTitle("Check running time - click!")
.setContentText(String.valueOf(elapsedTime))
.setContentIntent(pendingIntent)
.setDefaults(Notification.DEFAULT_ALL)
.setPriority(Notification.PRIORITY_HIGH)
.setVibrate(new long[0])
.build();
The device that I'm trying to run the app is API 21. I've seen many threads, but no solution given works for me.

You need to do two things:
Make sure that your notification is properly configured. See: https://developer.android.com/guide/topics/ui/notifiers/notifications#Heads-up
AND make sure the phone is properly configured (I think this is where most get stuck).
Step 1. Configure the notification.
First, register your notification channel like so
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
String name = getString(R.string.channel_name);
String description = getString(R.string.channel_description);
int importance = NotificationManager.IMPORTANCE_HIGH; //Important for heads-up notification
NotificationChannel channel = new NotificationChannel("1", name, importance);
channel.setDescription(description);
channel.setShowBadge(true);
channel.setLockscreenVisibility(Notification.VISIBILITY_PUBLIC);
NotificationManager notificationManager = getSystemService(NotificationManager.class);
notificationManager.createNotificationChannel(channel);
}
Then, create a notification, like so:
NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this, "1")
.setSmallIcon(R.drawable.notification_icon)
.setContentTitle(textTitle)
.setContentText(textContent)
.setDefaults(DEFAULT_SOUND | DEFAULT_VIBRATE) //Important for heads-up notification
.setPriority(Notification.PRIORITY_MAX); //Important for heads-up notification
Finally, send the notifciations as you would do normally, e.g.:
Notification buildNotification = mBuilder.build();
NotificationManager mNotifyMgr = (NotificationManager) context.getSystemService(NOTIFICATION_SERVICE);
mNotifyMgr.notify(001, buildNotification);
Step 2. Configure the phone.
I noticed that I have to enable some additional settings on my phone (a Xiaomi Note 3):
Here are some ways to reach the menu:
Long press a notification, in the notification bar.
Go to: Settings > Installed apps > Select your app > Notifications
Improving on the previous step, you can help users partially by sending them to the installed apps menu, by using this intent:
startActivity(new Intent(Settings.ACTION_MANAGE_APPLICATIONS_SETTINGS));
Finally, when you reach this menu enable a setting called something like "Floating notification" (the name of this setting varies between devices).

your code is almost fine. I'm using DEFAULT_VIBRATE instead of DEFAULT_ALL:
builder.setPriority(Notification.PRIORITY_HIGH);
if (Build.VERSION.SDK_INT >= 21) {
mBuilder.setDefaults(Notification.DEFAULT_VIBRATE);
}
But, you can also set
builder.fullScreenIntent(sameAsContentPendingtIntent);
but ^ this one is non-deterministic. I mean that system choose to display a HeadsUp or launch Intent. In most cases it shows HeadUp, but I'm not counting on it because of Android versions, Manufacturers, launchers and so so on.
Not at last, you also need to define right Notification Channel. I think you had already done this, because you wouldn't see any notification if you don't :-) Oh lovely Android :-) Anyway, I want to say that also NotificationChannel needs to be in high priority:
channel = new NotificationChannel("uniqueId", "name", NotificationManager.IMPORTANCE_HIGH);
channel.enableVibration(true);
And also, I advise to you, check latest opinions at developer.android.com
Google is going to be more strict from now. Not only for notifications but also for 'targetApi', but that is another story, pardon me :-)
Have a nice code today

try do this :
NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(context)
.setSmallIcon(android.R.drawable.arrow_up_float)
.setContentTitle("Check running time - click!")
.setContentText(String.valueOf(elapsedTime))
.setContentIntent(pendingIntent)
.setDefaults(Notification.DEFAULT_ALL)
.setPriority(Notification.PRIORITY_HIGH)
.setVibrate(new long[0]);
NotificationManager notificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
notificationManager.notify(0, notificationBuilder.build());

I've encountered the same issue. The solution is simply properly setting the vibration builder.setVibration(NotificationCompat.DEFAULT_VIBRATE).
According to Google:
The notification has high priority and uses ringtones or vibrations on devices running Android 7.1 (API level 25) and lower.
I hope it helps :)

The answers provided above were correct, but are partially correct now.
For future readers, notice that
.setDefaults(Notification.DEFAULT_ALL)
.setPriority(Notification.PRIORITY_HIGH)
will NOT resolve the problem.
According to "Android for developers",
https://developer.android.com/guide/topics/ui/notifiers/notifications.html#Heads-up
Example conditions that might trigger heads-up notifications include the following:
The user's activity is in fullscreen mode (the app uses fullScreenIntent).
The notification has high priority and uses ringtones or vibrations on devices running Android 7.1 (API level 25) and lower.
The notification channel has high importance on devices running Android 8.0 (API level 26) and higher.
Notice that the second solution (which is mostly mentioned under this question), only works for Android 7.1 or lower.
For Android 8.0 and higher, you should create a notification channel whose importance is NotificationManager.IMPORTANCE_HIGH.
Some sample code:
NotificationChannel channel =
new NotificationChannel(
"MY_OWN_CHANNEL_ID",
"MY_OWN_CHANNEL_NAME",
NotificationManager.IMPORTANCE_HIGH);
and after that, make sure that your notification builder uses this channel to display
NotificationCompat.Builder notificationBuilder =
new NotificationCompat.Builder(context)
.setSmallIcon(smallIcon)
.setContentTitle("Title")
.setContentText("Content")
.setChannelId("MY_OWN_CHANNEL_ID")
.setPriority(Notification.PRIORITY_HIGH)
.setVibrate(new long[0]);
Now you should be able to see heads-up notifications properly.

Just use like
NotificationManager mNotificationManager = (NotificationManager)
this.getSystemService(Context.NOTIFICATION_SERVICE);
Intent myintent = new Intent(this, MainActivity.class);
myintent.putExtra("message", msg);
PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
myintent, PendingIntent.FLAG_UPDATE_CURRENT);
NotificationCompat.Builder mBuilder =
new NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.ic_launcher)
.setContentTitle("ttile")
.setStyle(new NotificationCompat.BigTextStyle()
.bigText(msg))
.setContentText(msg);
mBuilder.setContentIntent(contentIntent);
mNotificationManager.notify(1, mBuilder.build());

real time notification by JSON format in android

i have an application about football/soccer , i'm using API for get information about the matches, i need a way to make a real time notification when a goal is added in this API which have a JSON format .

If you have access to your back end web service code, look into Google cloud messaging(gcm) service, it is made precisely for this purpose. If it is not feasible to use gcm, you need to set a repeating alarm, but it will not be as accurate as gcm. But I highly recommend going for gcm. Here's a link for your reference. GCM dev docs
Another work around for the case where you don't have access to source code for back end is to develop a middle layer sort of web service that keeps polling your back end and uses gcm to alert the clients. This way atleast you won't be wasting user's system resources.

This is how you pop a notification:
Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.logo_notification)
.setContentTitle(title)
.setContentText(body)
.setAutoCancel(true)
.setSound(defaultSoundUri)
.setVibrate(new long[] { 200, 200, 200})
.setContentIntent(pendingIntent);
NotificationManager notificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
notificationManager.notify(id, notificationBuilder.build()); //id is the notification id, if you use the same id, the notification will override the previous

In order to achieve the functionality,
Use a service to frequently(maybe once in 5 minutes) check information about the match.
If you have any Updates, show a notification to the user.
To show Notification:
PendingIntent pi = PendingIntent.getActivity(getApplicationContext(), 0, new Intent(), 0);
Notification notification = new NotificationCompat.Builder(getApplicationContext()).setTicker("Ticker Text").setSmallIcon("Icon").setContentTitle("Title").setContentText("Content Text").setContentIntent(pi).setAutoCancel(true).build();
NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
notificationManager.notify(0, notification);
For more info use this link
here

What you really want to do is have a Receiver that will run and check for updates. For real time updates, I would use a Socket.
It pretty much depends on your server.

Android notification is not showing

I need a program that will add a notification on Android. And when someone clicks on the notification, it should lead them to my second activity.
I have established code. The notification should be working, but for some reason it is not working. The Notification isn't showing at all. I don't know what am I missing.
Code of those files:
Notification n = new Notification.Builder(this)
.setContentTitle("New mail from " + "test#gmail.com")
.setContentText("Subject")
.setContentIntent(pIntent).setAutoCancel(true)
.setStyle(new Notification.BigTextStyle().bigText(longText))
.build();
NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
// Hide the notification after it's selected
notificationManager.notify(0, n);

The code won't work without an icon. So, add the setSmallIcon call to the builder chain like this for it to work:
.setSmallIcon(R.drawable.icon)
Android Oreo (8.0) and above
Android 8 introduced a new requirement of setting the channelId property by using a NotificationChannel.
NotificationManager mNotificationManager;
NotificationCompat.Builder mBuilder =
new NotificationCompat.Builder(mContext.getApplicationContext(), "notify_001");
Intent ii = new Intent(mContext.getApplicationContext(), RootActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(mContext, 0, ii, 0);
NotificationCompat.BigTextStyle bigText = new NotificationCompat.BigTextStyle();
bigText.bigText(verseurl);
bigText.setBigContentTitle("Today's Bible Verse");
bigText.setSummaryText("Text in detail");
mBuilder.setContentIntent(pendingIntent);
mBuilder.setSmallIcon(R.mipmap.ic_launcher_round);
mBuilder.setContentTitle("Your Title");
mBuilder.setContentText("Your text");
mBuilder.setPriority(Notification.PRIORITY_MAX);
mBuilder.setStyle(bigText);
mNotificationManager =
(NotificationManager) mContext.getSystemService(Context.NOTIFICATION_SERVICE);
// === Removed some obsoletes
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
{
String channelId = "Your_channel_id";
NotificationChannel channel = new NotificationChannel(
channelId,
"Channel human readable title",
NotificationManager.IMPORTANCE_HIGH);
mNotificationManager.createNotificationChannel(channel);
mBuilder.setChannelId(channelId);
}
mNotificationManager.notify(0, mBuilder.build());

Actually the answer by ƒernando Valle doesn't seem to be correct. Then again, your question is overly vague because you fail to mention what is wrong or isn't working.
Looking at your code I am assuming the Notification simply isn't showing.
Your notification is not showing, because you didn't provide an icon. Even though the SDK documentation doesn't mention it being required, it is in fact very much so and your Notification will not show without one.
addAction is only available since 4.1. Prior to that you would use the PendingIntent to launch an Activity. You seem to specify a PendingIntent, so your problem lies elsewhere. Logically, one must conclude it's the missing icon.

You were missing the small icon.
I did the same mistake and the above step resolved it.
As per the official documentation:
A Notification object must contain the following:
A small icon, set by setSmallIcon()
A title, set by setContentTitle()
Detail text, set by setContentText()
On Android 8.0 (API level 26) and higher, a valid notification channel ID, set by setChannelId() or provided in the NotificationCompat.Builder constructor when creating a channel.
See http://developer.android.com/guide/topics/ui/notifiers/notifications.html

This tripped me up today, but I realized it was because on Android 9.0 (Pie), Do Not Disturb by default also hides all notifications, rather than just silencing them like in Android 8.1 (Oreo) and before. This doesn't apply to notifications.
I like having DND on for my development device, so going into the DND settings and changing the setting to simply silence the notifications (but not hide them) fixed it for me.

Creation of notification channels are compulsory for Android versions after Android 8.1 (Oreo) for making notifications visible. If notifications are not visible in your app for Oreo+ Androids, you need to call the following function when your app starts -
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 behaviours after this
NotificationManager notificationManager =
getSystemService(NotificationManager.class);
notificationManager.createNotificationChannel(channel);
}
}

You also need to change the build.gradle file, and add the used Android SDK version into it:
implementation 'com.android.support:appcompat-v7:28.0.0'
This worked like a charm in my case.

I think that you forget the
addAction(int icon, CharSequence title, PendingIntent intent)
Look here: Add Action

I had the same issue with my Android app. I was trying out notifications and found that notifications were showing on my Android emulator which ran a Android 7.0 (Nougat) system, whereas it wasn't running on my phone which had Android 8.1 (Oreo).
After reading the documentation, I found that Android had a feature called notification channel, without which notifications won't show up on Oreo devices. Below is the link to official Android documentation on notification channels.
Notifications Overview, Notification anatomy
Create and Manage Notification Channels

For me it was an issue with deviceToken. Please check if the receiver and sender device token is properly updated in your database or wherever you are accessing it to send notifications.
For instance, use the following to update the device token on app launch. Therefore it will be always updated properly.
// Device token for push notifications
FirebaseInstanceId.getInstance().getInstanceId().addOnSuccessListener(
new OnSuccessListener<InstanceIdResult>() {
#Override
public void onSuccess(InstanceIdResult instanceIdResult) {
deviceToken = instanceIdResult.getToken();
// Insert device token into Firebase database
fbDbRefRoot.child("user_detail_profile").child(currentUserId).child("device_token")).setValue(deviceToken)
.addOnSuccessListener(
new OnSuccessListener<Void>() {
#Override
public void onSuccess(Void aVoid) {
}
});
}
});

I encountered a similar problem to yours and while searching for a solution I found these answers but they weren't as direct as I hoped they would be but it gives an Idea; Your notifications may not be showing because for versions >=8 notifications are done relatively differently there is a NotificationChannel which aids in managing notifications this helped me. Happy coding.
void Note(){
//Creating a notification channel
NotificationChannel channel=new NotificationChannel("channel1",
"hello",
NotificationManager.IMPORTANCE_HIGH);
NotificationManager manager=(NotificationManager) getSystemService(NOTIFICATION_SERVICE);
manager.createNotificationChannel(channel);
//Creating the notification object
NotificationCompat.Builder notification=new NotificationCompat.Builder(this,"channel1");
//notification.setAutoCancel(true);
notification.setContentTitle("Hi this is a notification");
notification.setContentText("Hello you");
notification.setSmallIcon(R.drawable.ic_launcher_foreground);
//make the notification manager to issue a notification on the notification's channel
manager.notify(121,notification.build());
}

Make sure your notificationId is unique. I couldn't figure out why my test pushes weren't showing up, but it's because the notification ids were generated based on the push content, and since I was pushing the same notification over and over again, the notification id remained the same.

Notifications may not be shown if you show the notifications rapidly one after the other or cancel an existing one, then right away show it again (e.g. to trigger a heads-up-notification to notify the user about a change in an ongoing notification). In these cases the system may decide to just block the notification when it feels they might become too overwhelming/spammy for the user.
Please note, that at least on stock Android (tested with 10) from the outside this behavior looks a bit random: it just sometimes happens and sometimes it doesn't. My guess is, there is a very short time threshold during which you are not allowed to send too many notifications. Calling NotificationManager.cancel() and then NotificationManager.notify() might then sometimes cause this behavior.
If you have the option, when updating a notification don't cancel it before, but just call NotificationManager.notify() with the updated notification. This doesn't seem to trigger the aforementioned blocking by the system.

If you are on version >= Android 8.1 (Oreo) while using a Notification channel, set its importance to high:
int importance = NotificationManager.IMPORTANCE_HIGH;
NotificationChannel channel = new NotificationChannel(CHANNEL_ID, name, importance);

val pendingIntent = PendingIntent.getActivity(applicationContext, 0, Intent(), 0)
var notification = NotificationCompat.Builder(applicationContext, CHANNEL_ID)
.setContentTitle("Title")
.setContentText("Text")
.setSmallIcon(R.drawable.icon)
.setPriority(NotificationCompat.PRIORITY_HIGH)
.setContentIntent(pendingIntent)
.build()
val mNotificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
mNotificationManager.notify(sameId, notification)