public void Metoda(View v) throws IOException, JSONException
    {
        TextView tv = (TextView) findViewById(R.id.wyswietl);

        JSONObject jsonObject = readJSONFromURL("http://api.fixer.io/latest?base=USD");
        String s =  jsonObject.get("rates").toString();


        tv.setText(s);
    }

    static JSONObject readJSONFromURL(String url) throws IOException, JSONException
    {

        InputStream inputStream =  new URL(url).openStream();

        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, Charset.forName("UTF-8")));

        String jsonText = readAllFromJSON(bufferedReader);

        return new JSONObject(jsonText);
    }

    private static String readAllFromJSON(BufferedReader bufferedReader) throws IOException
    {
        StringBuilder stringBuilder = new StringBuilder();
        int i;
        while((i = bufferedReader.read()) != -1)
        {
            stringBuilder.append((char) i);
        }

        return stringBuilder.toString();
    }