Save state of activity when orientation changes android

There are two ways of doing this, the first one is in the AndroidManifest.xml file. You can add this to your activity's tag 

android:configChanges="keyboardHidden|orientation|screenSize|screenLayout"

Or you can override two methods that will take care of this. This method requires some more effort, but arguably is much better. onSaveInstanceState saves the state of the activity before it's killed, and onRestoreInstanceState restores that information after onStart() Refer to the official documentation for a more in depth look.

In my sample code below, I am saving 2 int values, the current selection from the spinner as well as a radio button. 

 @Override
    public void onSaveInstanceState(@NonNull Bundle savedInstanceState) {
        spinPosition = options.getSelectedItemPosition();
        savedInstanceState.putInt(Constants.KEY, spinPosition);
        savedInstanceState.putInt(Constants.KEY_RADIO, radioPosition);
        super.onSaveInstanceState(savedInstanceState);

    }

    // And I am restoring those values with `getInt`, then I can pass those stored values into the spinner and radio button group to select the same values that we saved earlier. 

    @Override
    public void onRestoreInstanceState(@NotNull Bundle savedInstanceState) {
        spinPosition = savedInstanceState.getInt(Constants.KEY);
        radioPosition = savedInstanceState.getInt(Constants.KEY_RADIO);
        options.setSelection(spinPosition, true);
        type.check(radioPosition);
        super.onRestoreInstanceState(savedInstanceState);
    }

When your orientation changes, you don't have to manually change to the landscape layout file. Android does this automatically for you. When orientation changes, Android destroys your current activity and creates a new activity again, this is why you are losing the text.

There are 2 parts you need to do, assuming you want a separate layout for portrait and landscape.

  1. Assuming you have 2 XML layout files for portrait and landscape, put your main.xml layout file in the following folders:

    res/layout/main.xml <-- this will be your portrait layout
    res/layout-land/main.xml <-- this will be your landscape layout

    That's all you need to do, you don't have to touch the manifest file to modify android:configChanges="orientation" or override the onConfigurationChanged(). Actually, it's recommended you do not touch this for what you are trying to achieve.

  2. Now to save your text from the text view =) Lets assume your textview is named as MyTextView in your layout xml file. Your activity will need the following:

    private TextView mTextView;
private static final String KEY_TEXT_VALUE = "textValue";

@Override
protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   mTextView = (TextView) findViewById(R.id.main);
   if (savedInstanceState != null) {
      CharSequence savedText = savedInstanceState.getCharSequence(KEY_TEXT_VALUE);
      mTextView.setText(savedText);
   }
}

@Override
protected void onSaveInstanceState (Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putCharSequence(KEY_TEXT_VALUE, mTextView.getText());
}

Basically, whenever Android destroys and recreates your Activity for orientation change, it calls onSaveInstanceState() before destroying and calls onCreate() after recreating. Whatever you save in the bundle in onSaveInstanceState, you can get back from the onCreate() parameter.

So you want to save the value of the text view in the onSaveInstanceState(), and read it and populate your textview in the onCreate(). If the activity is being created for the first time (not due to rotation change), the savedInstanceState will be null in onCreate(). You also probably don't need the android:freezesText="true"

You can also try saving other variables if you need to, since you'll lose all the variables you stored when the activity is destroyed and recreated.

Tags:

Android

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