More than 1 different Urls and only One listview

Question

I am using webservices in my app. Basically my app shows a posts of wordpress site. User can also bookmark the posts.I am saving all book mark posts in sqlite with post urls. Now the problem is I have many different urls. And i want to show the content of these url in One ListView.

Also json structure of all these urls is same.

I have looked upon other question related to this issue but those aren't helping much.

Let me show you how much i have tried so far.

here is code this is code of BookmarkActivity

ArrayList<HashMap<String,String>> allData;
String[] urlarray;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_bookmark);
    SqliteController controller= new SqliteController(this);

    allData = controller.getAllData();
    for (int i=0; i<allData.size(); i++){
        String url=allData.get(i).get("link");
        urlarray= new String[]{url};
    }
    for(int i=0; i <urlarray.length; i++){
        MyAsyncTask task = new MyAsyncTask(i);
        task.execute();
    }
}
private class MyAsyncTask extends AsyncTask<Object,Void,String>{
    int urlNumber;
    HttpURLConnection connection=null;
    BufferedReader reader=null;
    public MyAsyncTask (int number){
        this.urlNumber=number;
    }
    @Override
    protected String doInBackground(Object... params) {
        try {
            URL url = new URL(urlarray[urlNumber]);
            connection= (HttpURLConnection) url.openConnection();
            connection.connect();
            StringBuffer buffer = new StringBuffer();
            String line = "";
            while ((line = reader.readLine()) != null) {
                buffer.append(line);
            }
            String json = buffer.toString();
            return json;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);
        //Log.d("TAG",s);
    }
}

here is json. (its not the exact same json but i am sure every url will have same json structure)

{
  "status": "ok",
  "count": 1,
  "count_total": 1,
  "pages": 1,
  "posts": [
    {
      "id": 1,
      "type": "post",
      "slug": "hello-world",
      "url": "http:\/\/localhost\/wordpress\/?p=1",
      "title": "Hello world!",
      "title_plain": "Hello world!",
      "content": "<p>Welcome to WordPress. This is your first post. Edit or delete it, then start blogging!<\/p>\n",
      "excerpt": "Welcome to WordPress. This is your first post. Edit or delete it, then start blogging!\n",
      "date": "2009-11-11 12:50:19",
      "modified": "2009-11-11 12:50:19",
      "categories": [],
      "tags": [],
      "author": {
        "id": 1,
        "slug": "admin",
        "name": "admin",
        "first_name": "",
        "last_name": "",
        "nickname": "",
        "url": "",
        "description": ""
      },
      "comments": [
        {
          "id": 1,
          "name": "Mr WordPress",
          "url": "http:\/\/wordpress.org\/",
          "date": "2009-11-11 12:50:19",
          "content": "<p>Hi, this is a comment.<br \/>To delete a comment, just log in and view the post's comments. There you will have the option to edit or delete them.<\/p>\n",
          "parent": 0
        }
      ],
      "comment_count": 1,
      "comment_status": "open"
    }
  ]
}

Can somebody help me with this. How should i work around with such situation?

Answer 1

try this one...Actually in this code am using Volley Library for Network Operations. First of all create Application class in your Application to avoid creating new instance of Volley library for network operations.

public class ApplicationController extends Application {

public static final String TAG = ApplicationController.class
        .getSimpleName();

private RequestQueue mRequestQueue;
private ImageLoader mImageLoader;

private static ApplicationController mInstance;

@Override
public void onCreate() {
    super.onCreate();
    mInstance = this;
}

public static synchronized ApplicationController getInstance() {
    return mInstance;
}

public RequestQueue getRequestQueue() {
    if (mRequestQueue == null) {
        mRequestQueue = Volley.newRequestQueue(getApplicationContext());
    }

    return mRequestQueue;
}

 //This function  request the volley library to process with tag
  //where <T> a generic method with an unbound type variable T.You can pass any datatype to functions.for more info About generic method.go through this link:http://docs.oracle.com/javase/tutorial/extra/generics/methods.html
public <T> void addToRequestQueue(Request<T> req, String tag) {
    // set the default tag if tag is empty
    req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
    getRequestQueue().add(req);
}
 //This function  request the volley library to process with tag
public <T> void addToRequestQueue(Request<T> req) {
    req.setTag(TAG);
    getRequestQueue().add(req);
}
//This function cancel the requested Url those are all in pending
public void cancelPendingRequests(Object tag) {
    if (mRequestQueue != null) {
        mRequestQueue.cancelAll(tag);
    }
}
}

In app build.gradle add this line under dependencies

 compile 'com.mcxiaoke.volley:library-aar:1.0.0'

In manifest file add this permission to access network

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

in Application tag mentioned the application class name

  <application
    android:name=".ApplicationController" 
     android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
     //your activity....
     </application>

In Activity onCreate add this line...

    progressDialog=new ProgressDialog(MainClass.this);
    progressDialog.setMessage("Loading...");
    progressDialog.show();
   //place your code to form urlarray
    urlarray = new String[5];
   //where datas represents the arraylist to store received content from json response.if you want to show more datas add your custom object to arraylist
    datas=new ArrayList<String>();

     adapter= new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, android.R.id.text1);
    try {
        for (int i = 0; i < urlarray.length; i++) {
            final int j = i;
            String url=urlarray[i];
            JsonObjectRequest objectRequest = new JsonObjectRequest(Request.Method.GET, url, (JSONObject) null, new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    Log.e("Response is for  " + Integer.toString(j), response.toString());
        //Here i assumed received json response is same as of sample json Provided by you.
                    try{
                    JSONArray jsonArray=response.getJSONArray("posts");
                    if(jsonArray.length()>0){
                        JSONObject obj=jsonArray.getJSONObject(0);
                        String content=obj.getString("content");
                        datas.add(content);
                    }
                    if(j==urlarray.length-1) {
                        progressDialog.dismiss();
                        adapter= new ArrayAdapter<String>(MainClass.this,
                                android.R.layout.simple_list_item_1, android.R.id.text1,datas);
                        listView.setAdapter(adapter);
                    }
                    }catch(Exception e){
                        e.printStackTrace();
                    }
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.e("error",error.toString());
                    if(j==urlarray.length-1) {
                        progressDialog.dismiss();
                    }
                    }
            }){
                @Override
                public Map<String, String> getHeaders() throws AuthFailureError {
                    HashMap<String, String> headers = new HashMap<String, String>();
                    headers.put("Content-Type", "application/json");
                    headers.put( "charset", "utf-8");
                    return headers;
                }
            };
            objectRequest.setRetryPolicy(new DefaultRetryPolicy(5000,
                    DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                    DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
        ApplicationController.getInstance().addToRequestQueue(objectRequest, "JSON");
        }

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

Answer 2

You should be doing every execution in the onBackground method after you get the result of one asynchronous call. This is because the async task executes on a different thread.

ArrayList<HashMap<String,String>> allData;
Iterator iterator;
ArrayList<String> urlarray = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_bookmark);
    SqliteController controller= new SqliteController(this);

    allData = controller.getAllData();
    for (int i=0; i<allData.size(); i++){
        String url=allData.get(i).get("link");
        urlarray.add(url);
    }
    iterator = urlarray.iterator();
    MyAsyncTask task = new MyAsyncTask();
    task.execute();

}
private class MyAsyncTask extends AsyncTask<Object,Void,ArrayList<String>>{
    int urlNumber;
    ArrayList<String> resultList  = new ArrayList<>();
    HttpURLConnection connection=null;
    BufferedReader reader=null;
    public MyAsyncTask (){

    }
    @Override
    protected String doInBackground(Object... params) {
        if(iterator.hasNext()) {
            try {

            URL url = new URL(iterator.next());
            connection= (HttpURLConnection) url.openConnection();
            connection.connect();
            StringBuffer buffer = new StringBuffer();
            String line = "";
            while ((line = reader.readLine()) != null) {
                buffer.append(line);
            }
            String json = buffer.toString();
            resultList.add(json);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        }
        return resultList;
    }
        @Override
        protected void onPostExecute(ArrayList<String> s) {
            super.onPostExecute(s);
            //Log.d("TAG",s);
            if(s.size > 0){
              //Your listview processing here.
            }
        }
    }