JSON Parsing without Any Library

Note: In Android, we can/Should not write any network base code in the main thread/same thread, it'll through an exception when we will try to run the app.

we should not do anything / any code which can be the cause of being the slow main thread.

main thread means UI thread.

we can use AsyncTask<> class, which generate a different thread ( for working in the background thread).
and this class have a doInBackground method.

[ Android Basic tutorial 21 (json parsing) - BITM ]

Some Important Links for using :

http://json.parser.online.fr/

http://www.sercandemir.com/

Yahoo Weather API as location in JSON Formate

http://services.hanselandpetal.com/feeds/flowers.json

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JSON Parsing:

আমাদের JSON parsing করতে হলে ২ টা part নিয়ে কাজ করতে হবে ।

Part:1

Connection

Part:2

AsyncTask

[ কারন এটা (AsyncTask ) আমাদের কে মেইন থ্রেড থেকে অন্য থ্রেড এ নিয়ে যায়। যেখানে কিছু মেথড (method) overriding করলেই হবে। ]

But for some reason, we are doing Part:1 first

Part:2 AsyncTask

---- make a private inner class within the main class and which extends by an

AsyncTask<String, Void, String>

----- and implement all the methods which need.

------ Now write the below code for formatting JSON object to string ... into doInBackground method .

-- some terms: HTTP request, setrequestMethod, connect().

@Override

protected String doInBackground(String... params) {
    URL url = null;
    try {
        url = new URL(params[0]);
        HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
        httpURLConnection.setRequestMethod("GET");
        httpURLConnection.connect(); //connect korar sathe sathe dataa asa suru hoye jabe
        //0/1 or binary data should collect in inputStream

        InputStream inputStream = httpURLConnection.getInputStream();

        //lets Decode it

        // utf-8  wise convert korbe

        InputStreamReader inputStreamReader = new InputStreamReader(inputStream,"UTF-8");

        
        //lets convert it as String
        //its easy with Buffer Reader

        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);

        //Now take a little little and set as stringBuilder

        StringBuilder stringBuilder = new StringBuilder();
        String line = "";
        while ((line = bufferedReader.readLine())  != null)
        {
            stringBuilder.append(line);
        }

        return  stringBuilder.toString();

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}

3. Now, onPostExecute we got the JSON Array.

-------- so here we should write some code to take the JSON array .

@Override

protected void onPostExecute(String s) {
    super.onPostExecute(s);

    try {
        JSONArray jsonArray = new JSONArray(s);
        JSONObject FlowerObject = jsonArray.getJSONObject(1);                 

        String FlowerName = FlowerObject.getString("name");

        FlowerTV.setText(FlowerName);

    } catch (JSONException e) {
        e.printStackTrace();
    }
}

Part:1 Connection

1. open your AndroidManifest.xml file -> and take permissions

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
.

2. for
the connection we use ConnectivityManager.
the network check we use NetworkInfo.

ConnectivityManager cm = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);

  NetworkInfo info = cm.getActiveNetworkInfo();

then we check if the network is available and is Connected? if yes then call the Asynctask execute, with the URL as a parameter.

if(info.isAvailable() && info.isConnected())

{
    new MyJSONDownloadTask().execute(Flower_Url);

   //execute()  call er sathe sathe doInBackground() run hobe and paramtr nibe}
else {

}

এই ব্লগটি সন্ধান করুন

Android Rough Book