How to connect a BroadcastReceiver to receive messages in Android?

There are two main methods:

1. Dynamic registration:

   • Registered and unregistered programmatically in the code.
   • Lives as long as the object that registered it is active.
   • Used for events that do not need to be received constantly or when the application is inactive (e.g., when changing orientation, battery level).

   // In Activity or Fragment
   private val receiver = object : BroadcastReceiver() {
       override fun onReceive(context: Context?, intent: Intent?) {
           // Handling the received message
           intent?.action?.let { action ->
               when (action) {
                   Intent.ACTION_BATTERY_CHANGED -> {
                       // Handling battery change
                   }
                   // Other actions
               }
           }
       }
   }
   
   override fun onResume() {
       super.onResume()
       val intentFilter = IntentFilter().apply {
           addAction(Intent.ACTION_BATTERY_CHANGED)
           // Other actions
       }
       registerReceiver(receiver, intentFilter)
   }
   
   override fun onPause() {
       super.onPause()
       unregisterReceiver(receiver)
   }
   

2. Static registration:

   • Declared in the manifest file (AndroidManifest.xml).
   • Lives longer than the lifecycle of the component that registered it. Can receive messages even when the application is inactive (with some limitations in recent Android versions).
   • Used for system events that need to be received constantly (e.g., device boot).

   <manifest xmlns:android="http://schemas.android.com/apk/res/android"
             package="com.example.yourapp">
   
       <application ...>
           <receiver android:name=".MyBroadcastReceiver"
                     android:exported="true"> <!-- Important for Android 12+ -->
               <intent-filter>
                   <action android:name="android.intent.action.BOOT_COMPLETED" />
                   <action android:name="android.intent.action.AIRPLANE_MODE" />
                   <!-- Other actions -->
               </intent-filter>
           </receiver>
           ...
       </application>
   </manifest>
   

   // BroadcastReceiver class
   class MyBroadcastReceiver : BroadcastReceiver() {
       override fun onReceive(context: Context?, intent: Intent?) {
           // Handling the received message
           intent?.action?.let { action ->
               when (action) {
                   Intent.ACTION_BOOT_COMPLETED -> {
                       // Handling boot completion
                   }
                   Intent.ACTION_AIRPLANE_MODE_CHANGED -> {
                       // Handling airplane mode change
                   }
                   // Other actions
               }
           }
       }
   }