How to check if stream in twitch.tv is on?

Question

Here is code of my getStream method:

public static Twitch_Stream getStream(String channelname) {
        try {
            String json = API.readJsonFromUrl("https://api.twitch.tv/kraken/streams?channel=" + channelname);

            Twitch_Stream stream = new Twitch_Stream();
            if (json.equalsIgnoreCase("[]")) {
                stream.setOnline(false);
                return stream;
            }

            JsonArray jb = gson.fromJson(json, JsonArray.class);
            if (jb.size() != 0) {
                JsonObject jo = (JsonObject) jb.get(0);
                stream.setOnline(true);
                stream.load(jo);
            }

            return stream;
        } catch (Exception error) {
            error.printStackTrace();
        }

        return null;

    }

and here is code of Twitch_Stream class http://pastebin.com/3RX1L1cv

When I make something like this

Twitch_Stream streamer = Twitch_API.getStream("Jankos");
Bukkit.broadcastMessage("getName " + streamer.getName());
Bukkit.broadcastMessage(streamer.isOnline() + "");

streamer.getName() return null and streamer.isOnline() returns false, even when stream is on.

Where did I make a mistake?

Answer 1

I don't know what problem is in your code but simple workaround would be reading content from "https://api.twitch.tv/kraken/streams/" + channel which is JSON in format:

{
    "_links" : {
       //links to stream and channel
    },
    "stream" : {
       //details about current stream
    }
}

Now if value of stream key is null stream is off-line. If it is not null, it is on-line.

So your code can look like

public static void main(String[] argv) throws IOException {

    System.out.println(checkIfOnline("Jankos"));
    System.out.println(checkIfOnline("nightblue3"));

}

public static boolean checkIfOnline(String channel) throws IOException {
    String channerUrl = "https://api.twitch.tv/kraken/streams/" + channel;

    String jsonText = readFromUrl(channerUrl);// reads text from URL
    JSONObject json = new JSONObject(jsonText);

    return !json.isNull("stream");
}

private static String readFromUrl(String url) throws IOException {
    URL page = new URL(url);
    try (Stream<String> stream = new BufferedReader(new InputStreamReader(
            page.openStream(), StandardCharsets.UTF_8)).lines()) {
        return stream.collect(Collectors.joining(System.lineSeparator()));
    }
}

I used JSONObject from org.json library. I am also using Java 8 and its streams.

If you want to use gson you can use instead something like

public static boolean checkIfOnline(String channel) throws IOException {
    String channerUrl = "https://api.twitch.tv/kraken/streams/" + channel;

    String jsonText = readFromUrl(channerUrl);// reads text from URL

    JsonParser parser = new JsonParser();
    JsonObject json = parser.parse(jsonText).getAsJsonObject();

    return !json.get("stream").isJsonNull();
}

If you don't have Java 8 you can rewrite code reading text from URL to something like

private static String readFromUrl(String url) throws IOException {
    URL page = new URL(url);
    StringBuilder sb = new StringBuilder();
    Scanner scanner = null;
    try{
        scanner = new Scanner(page.openStream(), StandardCharsets.UTF_8.name());
        while (scanner.hasNextLine()){
            sb.append(scanner.nextLine());
        }
    }finally{
        if (scanner!=null)
            scanner.close();
    }
    return sb.toString();
}

or from what I see you can use your API.readJsonFromUrl instead of readFromUrl.