Android在方向更改时保存状态

Question

I've got an Android application which maintains state regarding distance traveled, time elapsed, etc. This state I can conveniently store in an object and store a reference to that object in the Bundle when Android calls onDestroy() when the user changes the screen orientation, then restore the state in onCreate(Bundle savedBundle). However, I also have some state in the Buttons and EditText objects on the screen that I want to persist through screen orientations. For example, in onStart(Bundle savedBundle) I call:

_timerButton.setBackgroundColor(Color.GREEN);
_pauseButton.setBackgroundColor(Color.YELLOW);
_pauseButton.setEnabled(false);

Then throughout the operation of my app, the colors/enabled status of these buttons will be changed. Is there a more convenient way to persist the state of user interface items (EditText, Button objects, etc) without having to manually save/restore each attribute for each button? It feels really clumsy to have to manually manage this type of state in between screen orientations.

Thanks for any help.

Answer 1

Have you tried using: its work through

<activity name= ".YourActivity" android:configChanges="orientation|screenSize"/>

in Manifest file?

It does not work by default because , when you change the orientation onCreate will be called again and it redraws your view.

If you write this parameter no need to handle in Activity , the framework will take care of rest of things. It will retain the state of the screen or layout if orientation is changed.

NOTE If you are using a different layout for landscape mode , by adding these parameters the layout for landscape mode will not be called.

Other way and Another way

Answer 2

To save your variable or values you should use onSaveInstanceState(Bundle); and when orientation changes then should recover values should use onRestoreInstanceState() as well, but not very common. ( onRestoreInstanceState() is called after onStart(), whereas onCreate() is called before onStart() . Use the put methods to store values in onSaveInstanceState()

protected void onSaveInstanceState(Bundle icicle) {
  super.onSaveInstanceState(icicle);
  icicle.putLong("param", value);
}

And restore the values in onCreate() :

public void onCreate(Bundle icicle) {
  if (icicle != null){
    value = icicle.getLong("param");
  }
}