quickly change Android system language

I'm studying mandarin and want to change the language of my Android smartphone (Sony Xperia) between english/mandarin (or english/mandarin/portuguese/spanish) faster than using the default system settings. The way it is, I have to enter settings, scroll to the middle of it (which is slower than if it was on the beginning or end of the list), click Language & input, click language, have to scroll all the way down to 中文 (it should already be at the top, among the "recently used languages", but only my native language is always there), click 中文 and finally click ok.

I would like to reduce those 6+ clicks to a single button in the quick settings area (there is space for 4 more icons): when the phone is in a language, a tap on the icon would change to the next language, holding the icon would open a menu to add/remove languages/change order/etc.

I'm new to Android development, so I don't know if it's possible for an app to change the system language (need root privileges? I want it for myself, even if I won't be allowed to share it on Google Play, for instance). I've seen many answers on how to change an app language, that's not what I'm looking for. I also found many apps in Google Play, all of them promising to "quick toggle system language" etc, but none of them worked on my device. The closest I got was this, but looks like a dead thread.

So, is it possible? If so, where is the documentation?

I think this is what you might looking for!!!

If you would like to have your own application you can try this app i just created for you here!!!

Language Picker Widget

The Java Code

public class MainActivity extends Activity {
    private Button btn;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn = (Button)findViewById(R.id.add_button);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //in the line below it tells it to go to the language selection list
                Intent intent = new Intent(Settings.ACTION_LOCALE_SETTINGS);
                startActivity(intent);
                MainActivity.this.finish();


            }
        });
    }

}

The Layout File

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Change System Language"
        android:id="@+id/add_button"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

You can start a project in eclipse, use the codes above for the activity and the layout and then test it on the emulator