What are Intents used for in Android?

Intents in Android are used for:

• Starting an Activity: Transition between screens or launching external applications.

  // Starting an Activity
  val intent = Intent(this, AnotherActivity::class.java)
  startActivity(intent)
  

• Starting a Service: Performing background operations.

  // Starting a background service
  val intent = Intent(this, MyService::class.java)
  startService(intent)
  

• Sending broadcast messages: Notifying other system components about events.

  // Sending a broadcast message
  val intent = Intent("com.example.MY_CUSTOM_ACTION")
  sendBroadcast(intent)
  

• Passing data between components: Extras can be added to Intents.

  // Passing data between Activities
  val intent = Intent(this, DisplayMessageActivity::class.java).apply {
      putExtra("EXTRA_MESSAGE", "Hello from previous Activity!")
  }
  startActivity(intent)
  

• Implicit actions (Implicit Intents): Performing actions without specifying a particular component, allowing the system to choose an appropriate app.

  // Opening a web page
  val webpage: Uri = Uri.parse("http://www.android.com")
  val intent = Intent(Intent.ACTION_VIEW, webpage)
  startActivity(intent)
  

They serve as a kind of message describing the intention to perform some action.