How to download String file which contain special characters of slovenia

You need to encode string bytes to UTF-8. Please check following code :

String slovenianJSON = new String(value.getBytes([Original Code]),"utf-8");
JSONObject newJSON = new JSONObject(reconstitutedJSONString);
String javaStringValue = newJSON.getString("content");

I hope it will help you!

Decoding line in while loop can work. Also you should add your connection in try catch block in case of IOException

URL url = new URL(f_url[0]);
try {
    URLConnection conection = url.openConnection();
    conection.connect();
    InputStream input1 = new BufferedInputStream(url.openStream(), 300);
    String myData = "";
    BufferedReader r = new BufferedReader(new InputStreamReader(input1));
    StringBuilder totalValue = new StringBuilder();
    String line;
    while ((line = r.readLine()) != null) {
        line = URLEncoder.encode(line, "UTF8");
        totalValue.append(line).append('\n');
    }
    input1.close();
    String value = totalValue.toString();
    Log.v("To Check Problem from http paramers", value);
} catch (Exception e) {
    Log.v("Exception Character Isssue", "" + e.getMessage());
}

It's not entirely clear why you're not using Android's JSONObject class (and related classes). You can try this, however:

String str = new String(value.getBytes("ISO-8859-1"), "UTF-8");

But you really should use the JSON libraries rather than parsing yourself