import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class JSONParser {

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

        System.out.println("Enter Stock Symbol: ");
        String stockSymbol = new String(new BufferedReader(
                new InputStreamReader(System.in)).readLine());
        String jsonString = jsonURLToString(stockSymbolToURL(stockSymbol));
        System.out.println(getJsonKeyValue(jsonString, "change"));
    }

    static String jsonURLToString(String urlString) throws IOException {

        URL url = new URL(urlString);

        HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
        if (httpConn.getResponseCode() == HttpURLConnection.HTTP_OK) {

            String jsonString = new BufferedReader(new InputStreamReader(
                    url.openStream())).readLine().toString();

            return jsonString.trim();
        } else {
            return "Could not connect";
        }
    }

    static String stockSymbolToURL(String stockSymbol) {

        String urlString = "http://query.yahooapis.com/v1/public/yql?"
                + "q=select%20*%20from%20yahoo.finance.quote%20where%20"
                + "symbol%20in%20(%22" + stockSymbol
                + "%22)&format=json&diagnostics=t"
                + "rue&env=store%3A%2F%2Fdatatables.org%2Falltableswith"
                + "keys&callback=";
        return urlString;
    }

    static String getJsonKeyValue(String jsonString, String key) {

        String errorMessage = "getJsonArray: first argument does not contain second argument";
        String jsonValue = new String("");

        if (jsonString.contains(key)) {

            for (int i = 0; i < jsonString.length() - 1; i++) {

                if (jsonString.charAt(i) == '\"') {

                    if (jsonString.substring(i + 1, i + key.length() + 1)
                            .equalsIgnoreCase(key)) {

                        i += key.length() + 1;

                        if (jsonString.charAt(i) == '\"') {
                            i += 3;

                            while (jsonString.charAt(i) != '\"') {

                                jsonValue += jsonString.charAt(i);
                                i++;
                            }
                        }
                        return jsonValue;
                    }
                }
            }
            return jsonValue;
        } else {
            return errorMessage;
        }
    }
}