<activity android:name=".MyActivity"
android:screenOrientation="portrait"
android:label="@string/app_name">

@Override
public Object onRetainNonConfigurationInstance() {
final MyDataObject data = collectMyLoadedData();
return data;
}

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final MyDataObject data = (MyDataObject) getLastNonConfigurationInstance();
if (data == null) {//表示不是由于Configuration改變觸發的onCreate()
data = loadMyData();
}
...
}

<activity android:name=".MyActivity"
android:configChanges="orientation|keyboardHidden"
android:label="@string/app_name">

@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);

// Checks the orientation of the screen
if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
Toast.makeText(this, "橫屏模式", Toast.LENGTH_SHORT).show();
} else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT){
Toast.makeText(this, "豎屏模式", Toast.LENGTH_SHORT).show();
}
}