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Android progress notifications in Kotlin

Progress notifications are useful when you want to notify users about the progress of an ongoing task, such as downloading a file or uploading data. Android provides a flexible system to display and update notifications. In this tutorial, we'll demonstrate how to implement a progress notification using Kotlin.

Prerequisites:

Android Studio with Kotlin support.
Basic knowledge of Kotlin and Android development.

1. Set up a new project:

Open Android Studio and create a new project. Choose an empty activity template.

2. Add the required permission:

In the AndroidManifest.xml file, add the following permission (if your operation, e.g., a download, requires internet access):

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

3. Create the Notification Channel:

Starting from Android Oreo (API 26), notification channels are required. In MainActivity.kt, add:

private fun createNotificationChannel() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        val name = "Progress Channel"
        val descriptionText = "Channel for progress notifications"
        val importance = NotificationManager.IMPORTANCE_LOW
        val channel = NotificationChannel("PROGRESS_CHANNEL_ID", name, importance).apply {
            description = descriptionText
        }
        val notificationManager: NotificationManager =
            getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
        notificationManager.createNotificationChannel(channel)
    }
}

Call this method in your onCreate method:

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    createNotificationChannel()
}

4. Implement the Progress Notification:

fun showProgressNotification() {
    val notificationManager =
        getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

    val builder = NotificationCompat.Builder(this, "PROGRESS_CHANNEL_ID")
        .setSmallIcon(R.drawable.ic_launcher_foreground)
        .setContentTitle("File Download")
        .setContentText("Download in progress")
        .setPriority(NotificationCompat.PRIORITY_LOW)
        .setOngoing(true)
        .setOnlyAlertOnce(true)
        .setProgress(100, 0, false)

    notificationManager.notify(1, builder.build())

    // Simulate progress
    val maxProgress = 100
    var currentProgress = 0
    val handler = Handler(Looper.getMainLooper())
    val runnable = object : Runnable {
        override fun run() {
            currentProgress += 10
            if (currentProgress <= maxProgress) {
                builder.setProgress(maxProgress, currentProgress, false)
                notificationManager.notify(1, builder.build())
                handler.postDelayed(this, 500) // update every half second
            } else {
                builder.setContentText("Download complete")
                    .setProgress(0, 0, false)
                    .setOngoing(false)
                notificationManager.notify(1, builder.build())
            }
        }
    }
    handler.post(runnable)
}

5. Triggering the Notification:

For demonstration purposes, add a button to your activity_main.xml:

<Button
    android:id="@+id/startDownloadBtn"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Start Download"
    android:layout_centerInParent="true"/>

Then in your MainActivity.kt:

val startDownloadBtn = findViewById<Button>(R.id.startDownloadBtn)
startDownloadBtn.setOnClickListener {
    showProgressNotification()
}

6. Run the App:

When you click the "Start Download" button, the progress notification will appear and simulate a download process.

Notes:

For real-world scenarios, you'll want to tie the progress updates to actual operations, e.g., downloading a file.
Ensure your app targets and tests on Android Oreo (API level 26) or higher, so you can use notification channels.
Always ensure your notifications enhance the user experience and aren't intrusive.

Creating indeterminate progress notifications in Android using Kotlin

Description: Indeterminate progress notifications display a spinning progress indicator, indicating that a task is ongoing but the progress is unknown.

Code (Notification creation with indeterminate progress):

val notificationBuilder = NotificationCompat.Builder(this, CHANNEL_ID)
    .setSmallIcon(R.drawable.ic_notification)
    .setContentTitle("Downloading")
    .setContentText("File in progress")
    .setProgress(0, 0, true) // Indeterminate
    .setOngoing(true)

val notificationManager = NotificationManagerCompat.from(this)
notificationManager.notify(NOTIFICATION_ID, notificationBuilder.build())

Updating progress in ongoing notifications with Kotlin

Description: Update the progress in ongoing notifications to reflect the current status of a task.

Code (Updating progress in an ongoing notification):

val notificationBuilder = NotificationCompat.Builder(this, CHANNEL_ID)
    .setSmallIcon(R.drawable.ic_notification)
    .setContentTitle("Downloading")
    .setContentText("File in progress")
    .setProgress(100, progress, false) // Determinate progress
    .setOngoing(true)

val notificationManager = NotificationManagerCompat.from(this)
notificationManager.notify(NOTIFICATION_ID, notificationBuilder.build())

Customizing progress bar notifications in Android with Kotlin

Description: Customize the appearance of progress bar notifications by adjusting properties like color and style.

Code (Customizing progress bar in notification):

val notificationBuilder = NotificationCompat.Builder(this, CHANNEL_ID)
    .setSmallIcon(R.drawable.ic_notification)
    .setContentTitle("Downloading")
    .setContentText("File in progress")
    .setProgress(100, progress, false)
    .setColor(ContextCompat.getColor(this, R.color.notification_color))
    .setStyle(NotificationCompat.DecoratedCustomViewStyle())
    .setCustomContentView(customView) // Your custom view for notification

val notificationManager = NotificationManagerCompat.from(this)
notificationManager.notify(NOTIFICATION_ID, notificationBuilder.build())

Handling multiple progress notifications in Kotlin for Android

Description: Handle multiple progress notifications by using unique notification IDs for each task.

Code (Handling multiple progress notifications):

val notificationBuilder = NotificationCompat.Builder(this, CHANNEL_ID)
    .setSmallIcon(R.drawable.ic_notification)
    .setContentTitle("Task $taskId")
    .setContentText("Task in progress")
    .setProgress(100, progress, false)
    .setOngoing(true)

val notificationManager = NotificationManagerCompat.from(this)
notificationManager.notify(taskId, notificationBuilder.build())

Implementing determinate progress notifications in Kotlin

Description: Determinate progress notifications display a progress bar with a specific completion percentage.

Code (Creating determinate progress notification):

val notificationBuilder = NotificationCompat.Builder(this, CHANNEL_ID)
    .setSmallIcon(R.drawable.ic_notification)
    .setContentTitle("Uploading")
    .setContentText("File in progress")
    .setProgress(100, progress, false) // Determinate progress
    .setOngoing(true)

val notificationManager = NotificationManagerCompat.from(this)
notificationManager.notify(NOTIFICATION_ID, notificationBuilder.build())

Notification channels and progress notifications in Android with Kotlin

Description: Notification channels are used to group notifications. Define a channel for progress notifications.

Code (Creating a notification channel):

val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    val channel = NotificationChannel(
        CHANNEL_ID,
        "Progress Notifications",
        NotificationManager.IMPORTANCE_LOW
    )
    notificationManager.createNotificationChannel(channel)
}

Canceling and dismissing progress notifications in Kotlin

Description: Cancel or dismiss progress notifications when the associated task is completed or canceled.

Code (Canceling a notification):

val notificationManager = NotificationManagerCompat.from(this)
notificationManager.cancel(NOTIFICATION_ID)

Foreground service with progress notification in Android using Kotlin

Description: Use a foreground service to perform tasks in the background while keeping the app in the foreground and displaying a progress notification.

Code (Starting a foreground service with progress notification):

val serviceIntent = Intent(this, YourForegroundService::class.java)
serviceIntent.putExtra("inputExtra", "Foreground Service Example")

ContextCompat.startForegroundService(this, serviceIntent)