Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Android Build a Blog Reader Android App Adapting Data for Display in a List Handling Errors Using Dialogs

Rachit Agarwal
Rachit Agarwal
6,235 Points

Error dialog comes up for me!

Unfortunately, this error actually happens for me. I cross-checked my code with the project files from TeamTreehouse and they're essentially the same, aside from a few comments here and there. Whenever I open up the app, it brings up the dialog and says that there was an error getting the data from the blog. It also says "no items to display" in the listview. Please help! Thanks.

package com.rachitagarwal.blogreader;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.AlertDialog;
import android.app.ListActivity;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.text.Html;
import android.util.Log;
import android.view.MenuItem;
import android.view.View;
import android.widget.ProgressBar;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;

public class MainListActivity extends ListActivity {

    public static final int NUMBER_OF_POSTS = 20;
    public static final String BLOG_URL = "http://blog.teamtreehouse.com/api/get_recent_summary/?count=";
    public static final String TAG = MainListActivity.class.getSimpleName();
    protected JSONObject mBlogData;
    protected ProgressBar mProgressBar;

    private final String KEY_TITLE = "title";
    private final String KEY_AUTHOR = "author";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_list);

        mProgressBar = (ProgressBar) findViewById(R.id.progressBar1);

        if (isNetworkAvailable()) {
            mProgressBar.setVisibility(View.VISIBLE);
            GetBlogPostsTask getBlogPostsTask = new GetBlogPostsTask();
            getBlogPostsTask.execute();
        }
        else {
            Toast.makeText(this, "Network is unavailable!", Toast.LENGTH_LONG).show();
        }

        //Toast.makeText(this, getString(R.string.no_items), Toast.LENGTH_LONG).show();
    }

    private boolean isNetworkAvailable () {
        ConnectivityManager manager = (ConnectivityManager) getSystemService (Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = manager.getActiveNetworkInfo();
        boolean isAvailable = false;
        if(networkInfo!=null && networkInfo.isConnected()) {
            isAvailable = true;
        }
        return isAvailable;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    public void handleBlogResponse() {
        mProgressBar.setVisibility(View.INVISIBLE);

        if (mBlogData==null) {
            updateDisplayForError();
        }
        else {
            try {
                //Log.d(TAG, mBlogData.toString(2));
                JSONArray jsonPosts = mBlogData.getJSONArray("posts");
                ArrayList<HashMap<String, String>> blogPosts = new ArrayList<HashMap<String, String>>();


                for (int i=0; i<jsonPosts.length(); i++) {
                    JSONObject post = jsonPosts.getJSONObject (i);

                    String title = post.getString(KEY_TITLE);
                    title = Html.fromHtml(title).toString();
                    String author = post.getString(KEY_AUTHOR);
                    author = Html.fromHtml(author).toString();

                    HashMap<String, String> blogPost = new HashMap<String, String>();
                    blogPost.put(KEY_TITLE, title);
                    blogPost.put(KEY_AUTHOR, author);

                    blogPosts.add(blogPost);
                }

                String[] keys = { KEY_TITLE, KEY_AUTHOR };
                int[] ids = { android.R.id.text1, android.R.id.text2 };
                SimpleAdapter adapter = new SimpleAdapter (this, blogPosts, android.R.layout.simple_list_item_2, keys, ids);
                setListAdapter (adapter);

            } catch (JSONException e) {
                Log.e(TAG, "Exception caught: ", e);
            }
        }

    }

    private void updateDisplayForError() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle(getString(R.string.error_title));
        builder.setMessage(getString(R.string.error_message));
        builder.setPositiveButton(android.R.string.ok, null);
        AlertDialog dialog = builder.create();
        dialog.show();

        TextView emptyTextView = (TextView) getListView().getEmptyView();
        emptyTextView.setText(getString(R.string.no_items));
    }

    private class GetBlogPostsTask extends AsyncTask<Object, Void, JSONObject> {
        @Override
        protected JSONObject doInBackground (Object... arg0) {
            int responseCode = -1;
            JSONObject jsonResponse = null;

            try {
                URL blogFeedUrl = new URL(BLOG_URL + NUMBER_OF_POSTS);
                HttpURLConnection connection = (HttpURLConnection) blogFeedUrl.openConnection();
                connection.connect();

                responseCode = connection.getResponseCode();
                if (responseCode==HttpURLConnection.HTTP_OK) {
                    InputStream inputStream = connection.getInputStream();
                    Reader reader = new InputStreamReader(inputStream);
                    int contentLength = connection.getContentLength();
                    char[] charArray = new char[contentLength];
                    reader.read(charArray);
                    String responseData = new String (charArray);
                    Log.v(TAG, responseData);

                    jsonResponse = new JSONObject (responseData);
                    /*
                    String status = jsonResponse.getString ("status");
                    Log.v(TAG, status);
                    JSONArray jsonPosts = jsonResponse.getJSONArray("posts");
                    for (int i = 0; i<jsonPosts.length(); i++) {
                        JSONObject jsonPost = jsonPosts.getJSONObject(i);
                        String title = jsonPost.getString ("title");
                        Log.v(TAG, "Post " + i + ": " + title);
                    }*/
                }
                else {
                Log.i(TAG, "Unsuccessful HTTP Response Code: " + responseCode);
                }
            }
            catch(MalformedURLException e) {
                Log.e(TAG, "MalformedURLException caught: ", e);
            }
            catch (IOException e) {
                Log.e(TAG, "IOException caught: ", e);
            }
            catch (Exception e) { 
                Log.e(TAG, "Exception caught: ", e);
            }

            return jsonResponse;
        }

        @Override
        protected void onPostExecute (JSONObject result) {
            mBlogData = result;
            handleBlogResponse();
        }
    }
}