Can you explain who initiates the onSavedStateHandle function call in Android?

In Android, SavedStateHandle is used to save and restore the state of a ViewModel during recreation, such as during a screen rotation.

Functions or methods related to SavedStateHandle are usually called by the Android Architecture Components system. The initiator of the call is the ViewModelProvider framework, which passes the SavedStateHandle object to the ViewModel constructor when creating it.

That is, the developer declares a ViewModel with a SavedStateHandle parameter, and when the ViewModel is created, the system automatically passes this object. Example:

class MyViewModel(private val state: SavedStateHandle) : ViewModel() {
    fun saveData(data: String) {
        state.set("key", data)
    }

    fun getData(): String? {
        return state.get("key")
    }
}

Thus, the call and management of SavedStateHandle occur within the Android infrastructure, and the developer simply uses it to save the state.