how to write the AsyncTask in JSON parser for my code?

Question

I am developing a login application using MySQL database. I am using JSONParser from the database package to connect to the local mysql database I am getting the following error please some one help me. I googled for this error but what I got is to use the AsyncTask but I don't know where to use and how to use and what is the Mainthread also. Please some one edit my code and explain or post relevant codes... "android.os.NetworkonMainThreadException" is the error when I running the application from 4.2 genymotion emulator...

package com.android.database;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.util.Log;

public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";

    // constructor
    public JSONParser() {

    }

    public JSONObject getJSONFromUrl(String url, List<NameValuePair> params) {

        // Making HTTP request
        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);
            httpPost.setEntity(new UrlEncodedFormEntity(params));

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            json = sb.toString();
            Log.e("JSON", json);
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        // try parse the string to a JSON object
        try {
            jObj = new JSONObject(json);            
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }

        // return JSON String
        return jObj;

    }
}``

You try call network request in UI thread You should do it in new thread or asynctask — Konrad Krakowiak, Mar 02 '15 at 12:24
possible duplicate of [android.os.NetworkOnMainThreadException](http://stackoverflow.com/questions/6343166/android-os-networkonmainthreadexception) — Don Chakkappan, Mar 02 '15 at 12:29

score 0 · Answer 1 · answered Mar 02 '15 at 12:25

0

Network Operations must be done in background.

You can use AsyncTask to accomplish this.

answered Mar 02 '15 at 12:25

Don Chakkappan

7,397
5
44
59

score 0 · Answer 2 · answered Mar 02 '15 at 12:31

0

You are performing network operation on the UI thread and you can't do it. Consider using AsyncTask to do this kind operations, or an external library like this, which allows you to make Http request asynchronously in a very simple way.

answered Mar 02 '15 at 12:31

Morry

726
4
11

score 0 · Answer 3 · answered Mar 02 '15 at 12:33

I'm not sure if I understand your question correctly, and I would like to rather add a comment but am not allowed (too low rep) so here goes:

This class JSONParser i'm assuming is the "Activity" you are talking about. This is not an activity though, but a class, so you could rather create a new object of this class and use it from your calling activity:

JSONParser json = new JSONParser();
json.getJSONFromUrl(url,params);

Thing is, doing this parsing will take time and on the main UI thread this will probably pause the thread and might even let the app crash if the thread takes longer than 5 seconds to respond. This means you should use AsyncTask to run this JSONParser methods. A good place to start with learning AsyncTask is Vogella. He has some great tutorials on his site.

You will probably use doInBackground to run your getJSONFromUrl method and then update your UI thread from the onPostExecute method. So basically: Use AsyncTask

how to write the AsyncTask in JSON parser for my code?

3 Answers3