How to pass data from one fragment to another?

Bundle Arguments: Used for passing primitive data types and objects implementing Parcelable or Serializable when creating a new fragment instance.

// In the sending fragment
val bundle = Bundle().apply {
    putString("key", "value")
}
val fragment = TargetFragment().apply {
    arguments = bundle
}

// In the receiving fragment
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val value = arguments?.getString("key")
    // ... use of value
}

Shared ViewModel: Fragments belonging to the same Activity can use a shared ViewModel to exchange data.

// SharedViewModel
class SharedViewModel : ViewModel() {
    val data = MutableLiveData<String>()
}

// In the sending fragment
private val sharedViewModel: SharedViewModel by activityViewModels()
sharedViewModel.data.value = "value"

// In the receiving fragment
private val sharedViewModel: SharedViewModel by activityViewModels()
sharedViewModel.data.observe(viewLifecycleOwner) { value ->
    // ... use of value
}

Using interface callback: One fragment calls a method in the Activity, and the Activity then calls a method in another fragment.

// Interface in Activity or a separate file
interface DataTransferListener {
    fun onDataReceived(data: String)
}

// In the sending fragment
(activity as? DataTransferListener)?.onDataReceived("value")

// In the Activity implementing the interface
override fun onDataReceived(data: String) {
    val targetFragment = supportFragmentManager.findFragmentById(R.id.target_fragment_container) as? TargetFragment
    targetFragment?.updateUI(data)
}

// In the receiving fragment
fun updateUI(data: String) {
    // ... update UI with data
}

Fragment Result API: The modern and recommended way for exchanging data between fragments.

// In the sending fragment (set the result)
setFragmentResult("requestKey", bundleOf("bundleKey" to "value"))

// In the receiving fragment (listen for the result)
setFragmentResultListener("requestKey") { requestKey, bundle ->
    val result = bundle.getString("bundleKey")
    // ... use of result
}