Where does the bundle come from and where does it go in Android?

A Bundle in Android is used to pass data between application components (such as Activity, Fragment, Service, BroadcastReceiver).

Where it comes from:

• From the creating component: The component that initiates interaction with another component creates a Bundle and fills it with data.

Where it goes:

• To the receiving component: The created Bundle is passed to the target component.

Examples of usage:

• When launching an Activity via Intent. Data is added to the Intent using putExtra(), and then can be retrieved in the new Activity using getIntent().getExtras().
• When creating a Fragment and passing arguments to it. Data is added to a Bundle and set as arguments using setArguments().
• When passing data between Activity and Service or BroadcastReceiver via Intent.

Example of passing data between Activities:

// Sending Activity
val intent = Intent(this, TargetActivity::class.java)
val bundle = Bundle()
bundle.putString("key_string", "hello")
bundle.putInt("key_int", 123)
intent.putExtras(bundle)
startActivity(intent)

// Receiving Activity (TargetActivity)
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_target)

    val bundle = intent.extras
    if (bundle != null) {
        val stringValue = bundle.getString("key_string")
        val intValue = bundle.getInt("key_int")
        // Use the received data
    }
}