[Backボタン制御] #Android

MainActivity.kt

// legacy
public boolean onKeyDown(int keyCode, KeyEvent event) {
　　if (keyCode == KeyEvent.KEYCODE_BACK){
　　　　// do something...
　　} else {
　　　　return super.onKeyDown(keyCode, event);
　　}
}

MainFragment.kt

// use onBackPressedDispatcher
activity.onBackPressedDispatcher.addCallback(this@MainFragment) {
  // do something...
}