{ if (hasUnsavedInput()) { showConfirmationDialog() } else { finish() } } } 9 class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val onBackPressedCallback = object : OnBackPressedCallback(true) { override fun handleOnBackPressed() { if (hasUnsavedInput()) { showConfirmationDialog() } else { finish() } } } onBackPressedDispatcher.addCallback(this, onBackPressedCallback) } } onBackPressedのoverrideを置き換える