How to deal with JSON in Java (Android Studio)

Question

I'm new to android and i'm developing an Android App, i want to get JSON data from a URL : URL

I have the following code:

import java.io.IOException;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.os.Bundle;
import android.app.Activity;
import android.widget.TextView;
public class SingleContactActivity extends Activity {
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.article);
 String url = "http://ana.fm/api/article/256281468161349/";
 TextView title = (TextView) findViewById(R.id.single_article_title);
 TextView desc = (TextView) findViewById(R.id.single_article_desc);
 String str = "";
 HttpResponse response;
 HttpClient myClient = new DefaultHttpClient();
 HttpGet myConnection = new HttpGet(url);
 try {
 response = myClient.execute(myConnection);
 str = EntityUtils.toString(response.getEntity(), "UTF-8");
 } catch (ClientProtocolException e) {
 e.printStackTrace();
 } catch (IOException e) {
 e.printStackTrace();
 }
 try{
 JSONObject parent_obj = new JSONObject(str);
 JSONArray jArray= parent_obj.getJSONArray("article");
 JSONObject json = jArray.getJSONObject(0);
 title.setText(json.getString("title"));
 desc.setText(json.getString("description"));
 } catch ( JSONException e) {
 e.printStackTrace();
 }
 }
}

And this is article.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical" android:layout_width="match_parent"
 android:layout_height="match_parent">
 <!-- Article Cover Photo -->
 <ImageView
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:id="@+id/single_article_cover_photo"
 android:layout_gravity="center_horizontal" />
 <!-- Article Title -->
 <TextView
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:id="@+id/single_article_title"
 android:layout_gravity="center_horizontal"
 android:textColor="#acacac" />
 <!-- Article Description -->
 <TextView
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:id="@+id/single_article_desc"
 android:layout_gravity="center_horizontal" />
</LinearLayout>

And i have set the internet permission in AndroidManifest.xml:

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

But when i run the emulator i get: null null

I can't find anything wrong in my code.

I got it working with this code :

import java.io.IOException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.widget.TextView;
import java.io.InputStream;
public class SingleContactActivity extends Activity {
 public static String myArticleUrl = "http://ana.fm/api/article/256281468161349/";
 TextView title;
 TextView desc;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.article);
 title = (TextView) findViewById(R.id.single_article_title);
 desc = (TextView) findViewById(R.id.single_article_desc);
 new LoadAllArticles().execute();
 }
 // LOADING THE ARTICLE CONTENTS IN THE BACKGROUND
 class LoadAllArticles extends AsyncTask<String, String, Void> {
 private ProgressDialog progressDialog = new ProgressDialog(SingleContactActivity.this);
 InputStream inputStream = null;
 String result = "";
 HttpResponse httpResponse;
 HttpEntity httpEntity;
 protected void onPreExecute() {
 progressDialog.setMessage("Downloading article...");
 progressDialog.show();
 progressDialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
 public void onCancel(DialogInterface arg0) {
 LoadAllArticles.this.cancel(true);
 }
 });
 }
 @Override
 protected Void doInBackground(String... params) {
 String url_select = myArticleUrl;
 // Set up HTTP Get
 HttpClient httpClient = new DefaultHttpClient();
 HttpGet httpGet = new HttpGet(url_select);
 try {
 httpResponse = httpClient.execute(httpGet);
 result = EntityUtils.toString(httpResponse.getEntity(), "UTF-8");
 } catch (ClientProtocolException e) {
 e.printStackTrace();
 } catch (IOException e) {
 e.printStackTrace();
 }
 return null;
 }
 protected void onPostExecute(Void v) {
 //parse JSON data
 try {
 JSONObject parent_obj = new JSONObject(result);
 JSONArray jArray= parent_obj.getJSONArray("article");
 JSONObject json = jArray.getJSONObject(0);
 title.setText(json.getString("title"));
 desc.setText(json.getString("description"));
 this.progressDialog.dismiss();
 } catch (JSONException e) {
 Log.e("JSONException", "Error: " + e.toString());
 } // catch (JSONException e)
 }
 }
}

But now i need to deal with the HTML tags, anybody know how i can handle HTML tags in JSON ?

• Alexis C.: First of all, don't do HTTP requests in the main thread. You're subject to a NetworkOnMainThread exception. Move the code used to fetch the JSON datas to an asynctask.
• Fadi Obaji: and how can i do that ? @ZouZou
• zapl: It's in the documentation: developer.android.com/training/basics/network-ops/… - you can also use an even simpler approach: there are several libraries that are made specifically for async networking like volley or retrofit

Answer 1

EDIT: Ok, I finally managed to get to my working PC so I corrected all the errors, this is now working:

import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.widget.TextView;
import java.io.InputStream;
import java.util.ArrayList;
public class SingleContactActivity extends Activity {
 String myArticleUrl = "http://ana.fm/api/article/256281468161349/";
 TextView txtTitle;
 TextView txtDesc;
 JSONParser jParser = new JSONParser();
 JSONArray articles = null;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.article);
 txtTitle = (TextView) findViewById(R.id.single_article_title);
 txtDesc = (TextView) findViewById(R.id.single_article_desc);
 new LoadAllArticles().execute();
 }
 // LOADING ALL ARTICLES IN THE BACKGROUND
 class LoadAllArticles extends AsyncTask<String, String, String> {
 private ProgressDialog progressDialog = new ProgressDialog(SingleContactActivity.this);
 InputStream inputStream = null;
 String result = "";
 String title = "";
 String description = "";
 protected void onPreExecute() {
 progressDialog.setMessage("Downloading articles...");
 progressDialog.show();
 progressDialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
 public void onCancel(DialogInterface arg0) {
 LoadAllArticles.this.cancel(true);
 }
 });
 }
 @Override
 protected String doInBackground(String... params) {
 String url_select = myArticleUrl;
 ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
 try {
 JSONObject json = jParser.makeHttpRequest(url_select,
 "GET", param); // Change "GET" to "POST" if you want the POST method
 articles = json.getJSONArray("article");
 JSONObject jsonObj = articles.getJSONObject(0);
 title = jsonObj.getString("title");
 description = jsonObj.getString("description");
 }
 catch (IllegalStateException e3) {
 Log.e("IllegalStateException", e3.toString());
 e3.printStackTrace();
 }
 catch (JSONException e5) {
 Log.e("JSONException", e5.toString());
 e5.printStackTrace();
 }
 return null;
 }
 @Override
 protected void onPostExecute(String s) {
 try {
 String newTitle = Html.fromHtml(title).toString();
 txtTitle.setText(newTitle);
 String newDesc = Html.fromHtml(description).toString();
 txtDesc.setText(newDesc);
 progressDialog.dismiss();
 } catch (Exception e) {
 Log.e("JSONException", "Error: " + e.toString());
 }
 }
 }
}

And you need the JSONParser class:

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.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URLEncodedUtils;
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() {
 }
 // function get json from url
 // by making HTTP POST or GET mehtod
 public JSONObject makeHttpRequest(String url, String method,
 List<NameValuePair> params) {
 // Making HTTP request
 try {
 // check for request method
 if(method == "POST"){
 // request method is POST
 // 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();
 }else if(method == "GET"){
 // request method is GET
 DefaultHttpClient httpClient = new DefaultHttpClient();
 String paramString = URLEncodedUtils.format(params, "utf-8");
 url += "?" + paramString;
 HttpGet httpGet = new HttpGet(url);
 HttpResponse httpResponse = httpClient.execute(httpGet);
 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();
 } 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;
 }
} 

Try this, it is working for me, I can see a bunch of arabic text...

• Fadi Obaji: Thanks a lot! , let me test it and i'll get back to you.
• miselking: I edited some code, I think I made a mistake when declaring myArticleUrl, now should be fixed... Still cannot test though :(
• Fadi Obaji: I'm testing your code, but i changed HttpPost to HttpGet then i got this error : httpGet.setEntity(new UrlEncodedFormEntity(param)); "can't resolve method "setEntity"
• Fadi Obaji: Still not working, displaying "Downloading artile..." and the dialog never goes away
• miselking: Ok, I edited again with tested code that works for me... Hope this works for you as well... Vote up if you like ;)

Answer 2

Instead of anal parsing, you can use GSON . You will get your publications are java objects.

• gdaramouskas: Could you please define "anal parsing"?