private class MyTask extends AsyncTask<Void, Void, Void> {

    private String idFromServer;
    private String url="jdbc:mysql://192.168.1.xxx:xxxxx/test";
    String name = "AAA";

    @Override
    protected Void doInBackground(Void... params) {
        try {
            ResultSet result = null;
            String a = "SELECT * FROM testtable";
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            Connection con = DriverManager.getConnection(url,"aaa","abcdef");
            Statement state = con.createStatement();
            result = state.executeQuery(a);
            while (result.next()) {
                if (name.equals(result.getString("name"))) {
                    idFromServer = result.getString("id");
                }
            }
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }

    protected void onPostExecute(Void result) {
        id.setText(idFromServer);
        super.onPostExecute(result);
    }

}