Notifications

1. Giới thiệu

Notifications hiển thị thông tin cho user bên ngoài UI của app.

2. Setup

Permission (Android 13+)

<uses-permission android:name="android.permission.POST_NOTIFICATIONS" />

Request Permission

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
    if (checkSelfPermission(Manifest.permission.POST_NOTIFICATIONS)
        != PackageManager.PERMISSION_GRANTED) {
        requestPermissions(arrayOf(Manifest.permission.POST_NOTIFICATIONS), 100)
    }
}

3. Notification Channel (Android 8+)

private fun createNotificationChannel() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        val channel = NotificationChannel(
            "messages",
            "Messages",
            NotificationManager.IMPORTANCE_HIGH
        ).apply {
            description = "Chat message notifications"
            enableLights(true)
            lightColor = Color.BLUE
            enableVibration(true)
        }

        val manager = getSystemService(NotificationManager::class.java)
        manager.createNotificationChannel(channel)
    }
}

Importance Levels

Level	Behavior
IMPORTANCE_HIGH	Heads-up
IMPORTANCE_DEFAULT	Sound
IMPORTANCE_LOW	No sound
IMPORTANCE_MIN	Silent

4. Basic Notification

fun showNotification(context: Context) {
    val notification = NotificationCompat.Builder(context, "messages")
        .setSmallIcon(R.drawable.ic_notification)
        .setContentTitle("New Message")
        .setContentText("You have a new message from Alice")
        .setPriority(NotificationCompat.PRIORITY_HIGH)
        .setAutoCancel(true)
        .build()

    NotificationManagerCompat.from(context).notify(1, notification)
}

5. Notification với Action

val intent = Intent(context, ChatActivity::class.java)
val pendingIntent = PendingIntent.getActivity(
    context, 0, intent,
    PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT
)

val replyIntent = PendingIntent.getBroadcast(
    context, 0,
    Intent(context, ReplyReceiver::class.java),
    PendingIntent.FLAG_MUTABLE
)

val notification = NotificationCompat.Builder(context, "messages")
    .setSmallIcon(R.drawable.ic_message)
    .setContentTitle("New Message")
    .setContentText("Hello!")
    .setContentIntent(pendingIntent)
    .addAction(R.drawable.ic_reply, "Reply", replyIntent)
    .addAction(R.drawable.ic_mark_read, "Mark as Read", markReadIntent)
    .build()

6. Big Text/Picture Style

Big Text

val notification = NotificationCompat.Builder(context, "news")
    .setSmallIcon(R.drawable.ic_news)
    .setContentTitle("Breaking News")
    .setContentText("Short preview...")
    .setStyle(
        NotificationCompat.BigTextStyle()
            .bigText("This is a much longer text that will be shown when the notification is expanded...")
    )
    .build()

Big Picture

val notification = NotificationCompat.Builder(context, "photos")
    .setSmallIcon(R.drawable.ic_photo)
    .setContentTitle("New Photo")
    .setStyle(
        NotificationCompat.BigPictureStyle()
            .bigPicture(bitmap)
            .bigLargeIcon(null as Bitmap?)
    )
    .build()

7. Progress Notification

val builder = NotificationCompat.Builder(context, "downloads")
    .setSmallIcon(R.drawable.ic_download)
    .setContentTitle("Downloading...")
    .setPriority(NotificationCompat.PRIORITY_LOW)

val notificationManager = NotificationManagerCompat.from(context)

// Indeterminate
builder.setProgress(0, 0, true)
notificationManager.notify(1, builder.build())

// Determinate
for (progress in 0..100 step 10) {
    builder.setProgress(100, progress, false)
    notificationManager.notify(1, builder.build())
    delay(500)
}

// Complete
builder.setContentText("Download complete")
    .setProgress(0, 0, false)
notificationManager.notify(1, builder.build())

8. Messaging Style

val person = Person.Builder().setName("Alice").build()

val notification = NotificationCompat.Builder(context, "messages")
    .setSmallIcon(R.drawable.ic_message)
    .setStyle(
        NotificationCompat.MessagingStyle(person)
            .addMessage("Hi!", System.currentTimeMillis(), person)
            .addMessage("How are you?", System.currentTimeMillis(), person)
    )
    .build()

9. Direct Reply

val remoteInput = RemoteInput.Builder("key_text_reply")
    .setLabel("Reply...")
    .build()

val replyAction = NotificationCompat.Action.Builder(
    R.drawable.ic_reply,
    "Reply",
    replyPendingIntent
)
    .addRemoteInput(remoteInput)
    .build()

val notification = NotificationCompat.Builder(context, "messages")
    .setSmallIcon(R.drawable.ic_message)
    .setContentTitle("New Message")
    .addAction(replyAction)
    .build()

// Receive reply in BroadcastReceiver
val reply = RemoteInput.getResultsFromIntent(intent)
    ?.getCharSequence("key_text_reply")
    ?.toString()

10. Grouped Notifications

val GROUP_KEY = "com.example.MESSAGES"

// Individual notifications
messages.forEach { message ->
    val notification = NotificationCompat.Builder(context, "messages")
        .setSmallIcon(R.drawable.ic_message)
        .setContentTitle(message.sender)
        .setContentText(message.text)
        .setGroup(GROUP_KEY)
        .build()

    notificationManager.notify(message.id, notification)
}

// Summary notification
val summary = NotificationCompat.Builder(context, "messages")
    .setSmallIcon(R.drawable.ic_message)
    .setContentTitle("${messages.size} new messages")
    .setStyle(
        NotificationCompat.InboxStyle()
            .addLine("Alice: Hi!")
            .addLine("Bob: Hello!")
            .setSummaryText("${messages.size} messages")
    )
    .setGroup(GROUP_KEY)
    .setGroupSummary(true)
    .build()

notificationManager.notify(0, summary)

11. Cancel Notification

// By ID
notificationManager.cancel(notificationId)

// All
notificationManager.cancelAll()

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📝 Tóm tắt

Feature	API
Channel	NotificationChannel (Android 8+)
Permission	POST_NOTIFICATIONS (Android 13+)
Builder	NotificationCompat.Builder
Styles	BigTextStyle, BigPictureStyle, MessagingStyle
Actions	addAction()
Groups	setGroup(), setGroupSummary()