Sauver sur un stockage externe

bonjour;
j'essaie d'enregistrer un texte dans external storage mais je n'obtiens ni dossier ni fichier
mon code:

Code:

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 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_DENIED)
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, PackageManager.PERMISSION_GRANTED);
    }
    public void save(View v){
       Boolean b= Environment.isExternalStorageRemovable();
        File f = Environment.getExternalStorageDirectory();
// to this path add a new directory path
        File dir = new File(f.getAbsolutePath() + "/Queneau");
// create this directory if not already created
        dir.mkdir();
// create the file in which we will write the contents
        File file = new File(dir, "sonnet1.txt");
        String data = "Vive les vacances";
        try {
            OutputStreamWriter os = new OutputStreamWriter(getApplicationContext().openFileOutput("sonnet1.txt", Context.MODE_PRIVATE));
            os.write(data);
            os.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
 
 
    }

pouvez vous m'aider?merci