How to implement notification for ongoing downloads using DownloadManager in Kotlin Android

How to implement notification for ongoing downloads using DownloadManager in Kotlin Android.

Here is a detailed step-by-step tutorial on how to implement notification for ongoing downloads using DownloadManager in Kotlin Android:

Step 1: Set up the project

Create a new Android project in Kotlin.
Open the build.gradle file and add the following dependency:
```
implementation 'androidx.core:core-ktx:1.3.2'
```

Step 2: Create the layout file

Open the activity_main.xml file and add a Button with the id "downloadButton":

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

Step 3: Implement the download functionality

Open the MainActivity.kt file and import the necessary classes:

import android.app.DownloadManager
import android.content.BroadcastReceiver
import android.content.Context
import android.content.IntentFilter
import android.net.Uri
import android.os.Bundle
import android.os.Environment
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*

Declare a variable for the download ID:
```
private var downloadId: Long = 0
```

Initialize the DownloadManager and register a BroadcastReceiver to receive the download complete event:

private lateinit var downloadManager: DownloadManager
private lateinit var downloadCompleteReceiver: BroadcastReceiver

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

    downloadManager = getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager

    val filter = IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE)
    downloadCompleteReceiver = object : BroadcastReceiver() {
        override fun onReceive(context: Context, intent: Intent) {
            val id = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1)
            if (id == downloadId) {
                // Handle download complete event
            }
        }
    }
    registerReceiver(downloadCompleteReceiver, filter)
}

Set an OnClickListener for the downloadButton to start the download:
```
downloadButton.setOnClickListener {
    startDownload()
}
```

Implement the startDownload() function:

private fun startDownload() {
    val request = DownloadManager.Request(Uri.parse("YOUR_DOWNLOAD_URL"))
        .setTitle("File Download")
        .setDescription("Downloading")
        .setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE)
        .setDestinationInExternalFilesDir(
            this,
            Environment.DIRECTORY_DOWNLOADS,
            "filename.extension"
        )

    downloadId = downloadManager.enqueue(request)
}

Step 4: Display a notification for ongoing downloads

Add the necessary permission to the AndroidManifest.xml file:

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

Create a new class named DownloadNotificationHelper:

import android.app.Notification
import android.app.NotificationChannel
import android.app.NotificationManager
import android.app.PendingIntent
import android.content.Context
import android.content.Intent
import android.os.Build
import androidx.core.app.NotificationCompat

class DownloadNotificationHelper(private val context: Context) {
    private val notificationManager: NotificationManager =
        context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
    private val channelId = "download_channel"

    init {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            val channel = NotificationChannel(
                channelId,
                "Download",
                NotificationManager.IMPORTANCE_LOW
            )
            notificationManager.createNotificationChannel(channel)
        }
    }

    fun showNotification() {
        val intent = Intent(context, MainActivity::class.java)
        val pendingIntent = PendingIntent.getActivity(context, 0, intent, 0)

        val notification: Notification = NotificationCompat.Builder(context, channelId)
            .setContentTitle("Downloading")
            .setContentText("Download in progress")
            .setSmallIcon(android.R.drawable.stat_sys_download)
            .setContentIntent(pendingIntent)
            .setOngoing(true)
            .build()

        notificationManager.notify(1, notification)
    }

    fun hideNotification() {
        notificationManager.cancel(1)
    }
}

Modify the MainActivity.kt file to use the DownloadNotificationHelper:

private lateinit var downloadNotificationHelper: DownloadNotificationHelper

override fun onCreate(savedInstanceState: Bundle?) {
    // ...

    downloadNotificationHelper = DownloadNotificationHelper(this)
}

private fun startDownload() {
    // ...

    downloadNotificationHelper.showNotification()
}

override fun onDestroy() {
    super.onDestroy()
    unregisterReceiver(downloadCompleteReceiver)
    downloadNotificationHelper.hideNotification()
}

That's it! You have now implemented notification for ongoing downloads using DownloadManager in Kotlin Android.

Step 1: Set up the project​

Step 2: Create the layout file​

Step 3: Implement the download functionality​

Step 4: Display a notification for ongoing downloads​

Step 1: Set up the project

Step 2: Create the layout file

Step 3: Implement the download functionality

Step 4: Display a notification for ongoing downloads