JsonParsing.java

/* The date/time conversion code is going to be moved outside the asynctask later,
 * so for convenience we're breaking it out into its own method now.
 */
private String getReadableDateString(long time){
    // Because the API returns a unix timestamp (measured in seconds),
    // it must be converted to milliseconds in order to be converted to valid date.
    Date date = new Date(time * 1000);
    SimpleDateFormat format = new SimpleDateFormat("E, MMM d");
    return format.format(date).toString();
}

/**
 * Prepare the weather high/lows for presentation.
 */
private String formatHighLows(double high, double low) {
    // For presentation, assume the user doesn't care about tenths of a degree.
    long roundedHigh = Math.round(high);
    long roundedLow = Math.round(low);

    String highLowStr = roundedHigh + "/" + roundedLow;
    return highLowStr;
}

/**
 * Take the String representing the complete forecast in JSON Format and
 * pull out the data we need to construct the Strings needed for the wireframes.
 *
 * Fortunately parsing is easy:  constructor takes the JSON string and converts it
 * into an Object hierarchy for us.
 */
private String[] getWeatherDataFromJson(String forecastJsonStr, int numDays)
        throws JSONException {

    // These are the names of the JSON objects that need to be extracted.
    final String OWM_LIST = "list";
    final String OWM_WEATHER = "weather";
    final String OWM_TEMPERATURE = "temp";
    final String OWM_MAX = "max";
    final String OWM_MIN = "min";
    final String OWM_DATETIME = "dt";
    final String OWM_DESCRIPTION = "main";

    JSONObject forecastJson = new JSONObject(forecastJsonStr);
    JSONArray weatherArray = forecastJson.getJSONArray(OWM_LIST);

    String[] resultStrs = new String[numDays];
    for(int i = 0; i < weatherArray.length(); i++) {
        // For now, using the format "Day, description, hi/low"
        String day;
        String description;
        String highAndLow;

        // Get the JSON object representing the day
        JSONObject dayForecast = weatherArray.getJSONObject(i);

        // The date/time is returned as a long.  We need to convert that
        // into something human-readable, since most people won't read "1400356800" as
        // "this saturday".
        long dateTime = dayForecast.getLong(OWM_DATETIME);
        day = getReadableDateString(dateTime);

        // description is in a child array called "weather", which is 1 element long.
        JSONObject weatherObject = dayForecast.getJSONArray(OWM_WEATHER).getJSONObject(0);
        description = weatherObject.getString(OWM_DESCRIPTION);

        // Temperatures are in a child object called "temp".  Try not to name variables
        // "temp" when working with temperature.  It confuses everybody.
        JSONObject temperatureObject = dayForecast.getJSONObject(OWM_TEMPERATURE);
        double high = temperatureObject.getDouble(OWM_MAX);
        double low = temperatureObject.getDouble(OWM_MIN);

        highAndLow = formatHighLows(high, low);
        resultStrs[i] = day + " - " + description + " - " + highAndLow;
    }

    return resultStrs;
}