App restarts when it changes orientation (rotated)?

Question

I made this in my app:

• onCreate:

  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
  
  ...
  

• instances:

  @Override
  protected void onSaveInstanceState(Bundle outState){
      super.onSaveInstanceState(outState);//Salva Activity
      siteWebView.saveState(outState);//Salva WebView
  }
  
  @Override
  protected void onRestoreInstanceState(Bundle savedInstanceState){
      super.onRestoreInstanceState(savedInstanceState);//Restaura o Activity
      siteWebView.restoreState(savedInstanceState);//Restaura o WebView
  }
  

And in the manifest I used:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="br.com.foo.bar">

    <uses-permission android:name="android.permission.INTERNET" />

    <application
            android:allowBackup="true"
            android:icon="@mipmap/ic_launcher"
            android:label="@string/app_name"
            android:supportsRtl="true"
            android:configChanges="keyboardHidden|orientation|screenSize"
            android:theme="@style/AppTheme">
        <activity
                android:name=".MainActivity"
                android:label="@string/app_name"
                android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>

</manifest>

Answer 1

If you want Android does not recreate Activity every time you rotate the phone, just put in Manifest, within the tag Activity, the code:

<activity android:name=".MinhaActivity"
          android:configChanges="keyboardHidden|orientation" />

In the official documentation that is here you can find an excerpt (last paragraph) that guides (not explicitly) to use the configChanges.

You can also search for isChangingConfigurations which is available from the HONEYCOMB version of Android.

    @TargetApi(Build.VERSION_CODES.HONEYCOMB) 
    @Override
    public boolean isChangingConfigurations() {
        if(android.os.Build.VERSION.SDK_INT >= 11){
            Log.i("DEBUG", "Orientation changed api >= 11 ");
            return super.isChangingConfigurations();    
        }else {
            Log.i("DEBUG", "Orientation changed api < 11 ");
            return IsconfigChange; 
        }
    }

    @TargetApi(Build.VERSION_CODES.HONEYCOMB) 
    @Override
    protected void onStop() {
        super.onStop();
        if(isChangingConfigurations()){
            Log.i("DEBUG", "isChangingConfirgurations OnStop Called");
        }  else{
            Log.i("DEBUG", "OnStop Called");
        }
    }

Some time ago a professor of mine, of android, mentioned that the fact that he call onCreate, is because there and put the layout for Landscape and Portrait, and when we do (layouts with Landscape can be put in the layout-land folder that when the mobile phone is in landscape, will be automatically loaded) - and that according to my teacher, onCreate should do nothing but load the layout and initialize one variable or another.