Android: issue with data storage (SharedPreferences)

Question

I'm learning android and for this project I need to save user's data - color change of buttons, in this case -. During the program the change occurs (onClick), but when I restart the app, nothing happens - the change has not been saved (or read...) Can someone help me? Code:

   final String paintKey = "paint";

   protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    buttonCreate();
    preferences();
    togglePlay();
}

   public void preferences(){ //the issue in this method?

    SharedPreferences settings =   PreferenceManager.getDefaultSharedPreferences(this);
    data = settings.getString("stage", "Indoors");
    settings.getBoolean(paintKey,false);

    String backGround = settings.getString("stage", "Indoors");

    if (backGround.equals("Indoors")) {
        Picasso.with(this).load(R.drawable.shocked_crowd).fit().centerCrop().into(stage);

    }
    if (backGround.equals("Street")) {
        Picasso.with(this).load(R.drawable.coins).fit().centerCrop().into(stage);

    }
}

public void changeColor(){
    if(!paint) {    //paint variable has global scope and it is set to false
        c1.setBackgroundColor(Color.YELLOW);

        paint = true;
    }else{
        c1.setBackgroundColor(Color.BLUE);

        paint = false;
    }
    SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);
    SharedPreferences.Editor editor = settings.edit();
    editor.putBoolean("paint", paint);
    editor.commit();
}

EDIT: the onClick method:

public void onClick(View v) {

    if(v==color){

       changeColor();
    }

EDIT: this is how I have it now:

public void preferences(){

    SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);
    data = settings.getString("stage", "Indoors");
    final String paintKey = "paint";
    settings.getBoolean(paintKey,false);

Wrong? if I put editor instead of settings i get red underlined

Answer 1

In order to work with SharedPreferences you need a global key

final String paintKey = "paint"

To write boolean value info SharedPreferences use

SharedPreferences.Editor editor = PreferenceManager.getDefaultSharedPreferences(this).edit();
editor.putBoolean(paintKey, paint).commit();

To read that data later

paint = settings.getBoolean(paintKey, false);

Answer 2

settings.getBoolean(paintKey,false);

This line gets a value from the SharedPreferences and promptly ignores it. You must save the return value in a variable in order to use it later:

boolean paint = settings.getBoolean(paintKey,false);

This will create a local variable that can only be used in the same method. If you need to use the value in other methods, create a field instead.