Android : How can I write a parameter in .CSV file (Android)

I don't know how can I write a parameter or a line in a .csv File when I press a button in my app. I have this in my code, but I'm not sure if I need create another class or doing it in the method onCreate.

EditText newParam;
protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_menu_parametros);

        Button btnAgrParam = (Button) findViewById(R.id.btn_AgrParam);
      btnAgrParam.setOnClickListener(new OnClickListener() {
                public void onClick(View v) {

                    newParam = (EditText)findViewById(R.id.label_NewParam);
                    try{

                        String csv ="C:\\Users\\Rubén\\Desktop\\Universidad\\TFG\\Plantilla.csv";
                        CSVWriter writer;
                        writer = new CSVWriter(new FileWriter(csv));
                        String parametro = newParam.getText().toString();
                        String datos = parametro;
                        writer.writeNext(datos);

                        writer.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }

            });
}