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Java Problem - Listview

Discussion in 'Programming' started by scottlpool2003, Jan 16, 2015.

  1. #1
    I'm trying to create an Android app and I've only limited experience with Java so this is my first real-world app.

    What I'm trying to do is create a listview and the end result I am looking for is similar to:

    +========+
    |SCROLLVIEW |
    +========+
    |Listview line 1|
    |Listview line 2|
    |Listview line 1|
    |Listview line 2|
    |Listview line 1|
    |Listview line 2|
    +========+
    SEMrush
    I'm struggling even getting the listview working though with a nullpointer exception. I've noted it down as
    I'm a little clueless as to where to go from here so if anyone could help I'd be grateful.

    
    package info.androidhive.slidingmenu;
    
    import android.app.Fragment;
    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ArrayAdapter;
    import android.widget.ListView;
    import org.apache.http.HttpResponse;
    import org.apache.http.HttpStatus;
    import org.apache.http.StatusLine;
    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.json.JSONArray;
    import org.json.JSONException;
    import org.json.JSONObject;
    import java.io.ByteArrayOutputStream;
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.List;
    
    
    public class PhotosFragment extends Fragment {
        public PhotosFragment(){}
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_photos, container, false);
            new RequestTask().execute("http://www.myjsonurl.co.uk/app/index.php?Type=8&catid=7&userid=4");
    
            return rootView;
        }
    
        @Override
        public void onActivityCreated(Bundle savedInstanceState) {
            super.onActivityCreated(savedInstanceState);
    
            Log.v("created", "onActivityCreated()");
            setHasOptionsMenu(true);
    
        }
        private static final String TAG = MainActivity.class.getSimpleName();
        private static List<ListViewItem> mItems;        // ListView items list
        JSONObject obj;
        JSONArray stories;
    
        public class RequestTask extends AsyncTask<String, String, String> {
    
            @Override
            protected String doInBackground(String... uri) {
                HttpClient httpclient = new DefaultHttpClient();
                HttpResponse response;
                String responseString = null;
                try {
    
                    response = httpclient.execute(new HttpGet(uri[0]));
                    StatusLine statusLine = response.getStatusLine();
                    if (statusLine.getStatusCode() == HttpStatus.SC_OK) {
                        ByteArrayOutputStream out = new ByteArrayOutputStream();
                        response.getEntity().writeTo(out);
    
                        out.close();
                        responseString = out.toString();
    
                        //Do anything with response..
                        Log.d(TAG, responseString);
    
                    } else {
                        //Closes the connection.
                        response.getEntity().getContent().close();
                        throw new IOException(statusLine.getReasonPhrase());
                    }
                } catch (ClientProtocolException e) {
                    //TODO Handle problems..
                    Log.d(TAG, String.valueOf(e));
                } catch (IOException e) {
                    //TODO Handle problems..
                    Log.d(TAG, String.valueOf(e));
                }
                return responseString;
            }
    
            @Override
            protected void onPostExecute(String result) {
                super.onPostExecute(result);
    
                Log.e(TAG, result);
                try {
                    obj = new JSONObject(result);
                    stories = obj.getJSONArray("stories");
    
                    // initialize the items list
                    mItems = new ArrayList<ListViewItem>();
    
                    for (int i = 0; i < stories.length(); i++) {
    
                        JSONObject storyObj = stories.getJSONObject(i);
    
                        if (!storyObj.has("Advert")) {
    
                            newsStories newsStories = new newsStories();
    
                            newsStories.setTitle(storyObj.getString("subject"));
                            newsStories.setBody(storyObj.getString("body"));
    
                            mItems.add(new ListViewItem(newsStories.getTitle(), newsStories.getBody(), ""));
    
                        } else {
                            newsStories newsStories = new newsStories();
                            newsStories.setThumbnailUrl(storyObj.getString("Advert"));
                            mItems.add(new ListViewItem("", "", newsStories.getThumbnailUrl()));
    
                        }
    
                        // initialize and set the list adapter
                        //setListAdapter(new ListViewDemoAdapter(getActivity(), mItems));
    
                    }
    
                } catch (JSONException e) {
                    e.printStackTrace();
                }
    
                //mProgressBar = (ProgressBar) getView().findViewById(R.id.progressBar);
                ListView mListView = (ListView) getView().findViewById(R.id.listView2); //Here is the issue
                //mTvEmpty = (TextView) getView().findViewById(R.id.textView);
    
                Log.d("mListView: ", String.valueOf(mListView));
    
                ArrayAdapter<ListViewItem> adapter = new ArrayAdapter<ListViewItem>(getActivity(), android.R.layout.simple_list_item_1, mItems);
    
                Log.d("Adapter: ", String.valueOf(adapter));
    
                // load your data to your mListView
                mListView.setAdapter(adapter); //NULL POINTER
            }
    
    
    
            public class newsStories {
                private String name, thumbnailUrl, body;
    
                public String getTitle() {
                    return name;
                }
    
                public void setTitle(String name) {
                    this.name = name;
                }
    
                public String getBody() {
                    return body;
                }
    
                public void setBody(String body) {
    
                    this.body = body.substring(0, 150);
    
                }
    
    
                public String getThumbnailUrl() {
                    return thumbnailUrl;
                }
    
                public void setThumbnailUrl(String thumbnailUrl) {
                   
                    this.thumbnailUrl = thumbnailUrl;
    
                }
    
            }
    
        }
    
        public class ListViewItem {
            public final String title;        // the text for the ListView item title
            public final String description;  // the text for the ListView item description
            public final String adUrl;
            //public final Drawable image;
    
            public ListViewItem(String title, String description, String Advert_Url) {
    
    
    
    
                if (Advert_Url != null && !Advert_Url.isEmpty()) {
    
                    String Advert = "http://www.myurl.co.uk/images/advert.png?width=700&height=200";
    
    
                    this.title = "";
                    this.description = "";
                    this.adUrl = Advert;
    
                } else {
                    this.title = title;
                    this.description = description;
                    this.adUrl = "";
                }
    
    
            }
        }
    
    
    }
    
    Code (markup):
     
    scottlpool2003, Jan 16, 2015 IP
    SEMrush
  2. ThePHPMaster

    ThePHPMaster Well-Known Member

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    #2
    Before using findViewById the element needs to be in Activity (R.id.listView2) in this case. If you google "getView().findViewById" you can find many examples of that. I don't have my Java stack setup so I can't test this out.
     
    ThePHPMaster, Jan 17, 2015 IP
  3. scottlpool2003

    scottlpool2003 Well-Known Member

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    #3
    The problem is that I'm doing it Async so if I put it in the activity it tries to set the listview before the Async task has finished.
     
    scottlpool2003, Jan 19, 2015 IP