Save more than one data

Question

I have a doubt and I don't know how to solve it, if I have an ArrayList with only 3 positions with the values [1,2,3]. I would like that when the user adds for example the text [1], the data is saved in local mode in the device. And if later the user wants to add another text, for example [3].

At the end the SharedPreference would have saved the [1,3]. So if the user exits the app and re-enters, he can only redeem the text [2]. Because I already redeemed the [1,3].

I have the following, but I don't know how to continue correctly.

Promotional codes.

private ArrayList<String> codigoInvitacionAmigos;
codigoInvitacionAmigos.add("1");
codigoInvitacionAmigos.add("2");
codigoInvitacionAmigos.add("3");

Here is the button, for when the user clicks to redeem

 btClaimInvite.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Log.d("TODOS: ", codigoInvitacionAmigos.toString());
            String codigo_temporal = inpt_Promo_code.getText().toString();
            if(!codigo_temporal.isEmpty()){//comprobamos que NO este el campo vacío
                for(int i=0; i < codigoInvitacionAmigos.size(); i++){
                    if(codigoInvitacionAmigos.get(i).contains(codigo_temporal)){
                        Toast.makeText(Bonus.this, "COINCIDENCIA", Toast.LENGTH_LONG).show();
                        //Guardar_CodigoReclamadoYCanjeado(0, codigo_temporal);
                        //codigoInvitacionAmigos.remove(codigo_temporal);
                    }else{
                        Toast.makeText(Bonus.this, "No coincide", Toast.LENGTH_LONG).show();
                    }
                }
            }
        }
    });

And here's how I'm trying to save it

   private void Cargar_CodigoReclamadoYCanjeado(){
    SharedPreferences load_CodigosReclamados = getSharedPreferences("CODIGO_CLAIM", MODE_PRIVATE);
    String codi = load_CodigosReclamados.getString("codes_0", "");
    if(!codi.isEmpty())codigoInvitacionAmigos.remove(codi);
    Log.d("TODOS_Cargar", codi);

    String codi_1 = load_CodigosReclamados.getString("codes_1", "");
    if(!codi_1.isEmpty())codigoInvitacionAmigos.remove(codi_1);
    Log.d("TODOS_Cargar", codi_1);

}

private void Guardar_CodigoReclamadoYCanjeado(int posicion, String codigoCanjeado){
    SharedPreferences saved_CodigosReclamados = getSharedPreferences("CODIGO_CLAIM", MODE_PRIVATE);
    SharedPreferences.Editor editor = saved_CodigosReclamados.edit();
    switch (posicion){
        case 1:
            editor.putString("codes_1", codigoCanjeado);
            break;
        default:
            editor.putString("codes_0", codigoCanjeado);
            break;
    }
    editor.apply();
    Log.d("TODOS_Saved", "Entra Saved");
}

Answer 1

Save used codes in shared preferences as a comma separated string (e.g. "1,3")

String[] codes = {"1", "2", "3"};

boolean isCodeValid(String code) {
    for (String s : codes)
        if (s.equals(code)) return true;
    return false;
}

boolean isCodeUsed(String code) {
    String usedCodes = sharedPreferences.getString("used_codes", "");
    String[] usedCodesArray = usedCodes.split(",");
    for (String s : usedCodesArray)
        if (s.equals(code)) return true;
    return false;
}

void setCodeUsed(String code) {
    String usedCodes = sharedPreferences.getString("used_codes", "");
    usedCodes += code + ",";
    editor.putString("used_codes", usedCodes).apply();
}

Usage of functions :

String enteredCode = edtCode.getText().toString()

if (isCodeValid(enteredCode)) {
    if (isCodeUsed(enteredCode)) System.out.println("Code already used");
    else {
        System.out.println("Code valid and not yet used");
        setCodeUsed(enteredCode);
    }
} else System.out.println("Code not valid");