Read text file via HTTP

Question

I’m creating an app for Android with Android Studio and I’m having trouble reading a text file that is hosted on the Internet. Whenever I try to execute the method checkVersion() it returns the following error:

The message is empty because net.getMessage() is returning null

iPoema.java

public int getVersion() {
    int versao = 0;
    String linha = "0";
    BufferedReader in = null;
    try {
        HttpClient httpclient = new DefaultHttpClient();
        HttpGet request = new HttpGet();
        URI website = new URI("http://www.xadees.xpg.com.br/iPoema.txt");
        request.setURI(website);
        HttpResponse response = httpclient.execute(request);
        in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
        String sb;
        while ((sb = in.readLine()) != null) {
            linha += sb;
        }
        in.close();
        versao = Integer.parseInt(linha);
    } catch (NetworkOnMainThreadException net) {
        showMessage(net.getClass().getName(), net.getMessage());
    } catch (IOException io) {
        showMessage(io.getClass().getName(), io.getMessage());
    } catch (URISyntaxException use) {
        showMessage(use.getClass().getName(), use.getMessage());
    }
    return versao;
}

Answer 1

Network operations on Android must be asynchronous, IE, They can not be performed on the main thread not to run the risk of freezing the user screen during operation. Use a Asynctask to run your code outside the main thread (main thread).

Here are the simplest examples:

AsyncTask<Void, Void, String> MinhaTask = new AsyncTask<Void, Void, String>(){
    @Override
    protected String doInBackground(Void... params) {
        //Qualquer código aqui é executado fora da thread principal (Views não podem ser atualizadas)
        return "qualquer coisa";
    }

    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);
        //Após o return do método doInBackground, qualquer código aqui estará novamente na main thread (Views podem ser atualizadas)
    }
};

MinhaTask.execute();