JSON Weather Parser

JSON Weather Parser

Once we have created our model we have to parse it. We can create a specific class that handles this task. First we have to create the “root” object that receive as input the entire string containing all the JSON response:

1	// We create out JSONObject from the data

2	JSONObject jObj = new JSONObject(data);

Then we start parsing each piece of the response:

01	// We start extracting the info

02	Location loc = new Location();

03

04	JSONObject coordObj = getObject("coord", jObj);

05	loc.setLatitude(getFloat("lat", coordObj));

06	loc.setLongitude(getFloat("lon", coordObj));

07

08	JSONObject sysObj = getObject("sys", jObj);

09	loc.setCountry(getString("country", sysObj));

10	loc.setSunrise(getInt("sunrise", sysObj));

11	loc.setSunset(getInt("sunset", sysObj));

12	loc.setCity(getString("name", jObj));

13	weather.location = loc;

In the line 4,8 we create two “sub” object (coordObj and sysObj) having as parent the jObj as it clear from the JSON response. As we can see we use some helper methods to get String,int and float values:

01	private static JSONObject getObject(String tagName, JSONObject jObj)  throws JSONException {

02	JSONObject subObj = jObj.getJSONObject(tagName);

03	return subObj;

04

}

05

06	private static String getString(String tagName, JSONObject jObj) throws JSONException {

07	return jObj.getString(tagName);

08

}

09

10	private static float  getFloat(String tagName, JSONObject jObj) throws JSONException {

11	return (float) jObj.getDouble(tagName);

12

}

13

14	private static int  getInt(String tagName, JSONObject jObj) throws JSONException {

15	return jObj.getInt(tagName);

16

}

And then we finally parse the weather information. We have to remember that weather tag is an array so we have to handle it differently

01	// We get weather info (This is an array)

02	JSONArray jArr = jObj.getJSONArray("weather");

03

04	// We use only the first value

05	JSONObject JSONWeather = jArr.getJSONObject(0);

06	weather.currentCondition.setWeatherId(getInt("id", JSONWeather));

07	weather.currentCondition.setDescr(getString("description", JSONWeather));

08	weather.currentCondition.setCondition(getString("main", JSONWeather));

09	weather.currentCondition.setIcon(getString("icon", JSONWeather));

10

11	JSONObject mainObj = getObject("main", jObj);

12	weather.currentCondition.setHumidity(getInt("humidity", mainObj));

13	weather.currentCondition.setPressure(getInt("pressure", mainObj));

14	weather.temperature.setMaxTemp(getFloat("temp_max", mainObj));

15	weather.temperature.setMinTemp(getFloat("temp_min", mainObj));

16	weather.temperature.setTemp(getFloat("temp", mainObj));

17

18

// Wind

19	JSONObject wObj = getObject("wind", jObj);

20	weather.wind.setSpeed(getFloat("speed", wObj));

21	weather.wind.setDeg(getFloat("deg", wObj));

22

23

// Clouds

24	JSONObject cObj = getObject("clouds", jObj);

25	weather.clouds.setPerc(getInt("all", cObj));

At the end we have our Weather class filled with the data retrieved.