1

我制作了一个应用程序，在其中我正在获取产品列表及其名称、描述和图像，我能够在单击任何 ListView 项目行时以详细的产品表单显示图像，但显示图像时出现问题在 ListView 中，我不知道为什么会遇到这个问题..

请让我知道我在哪里失踪：

代码：

   public class CategoryActivity extends ListActivity {
    // Connection detector
    ConnectionDetector cd;      
    // Alert dialog manager
    AlertDialogManager alert = new AlertDialogManager();        
    // Progress Dialog
    private ProgressDialog pDialog;
    // Creating JSON Parser object
    JSONParser jsonParser = new JSONParser();
    ArrayList<HashMap<String, String>> albumsList;
    // albums JSONArray
    JSONArray albums = null;
    String imagepath;
    // albums JSON url
    private static final String URL_ALBUMS = "http://XXX.com/albums.php";

    // ALL JSON node names
    static final String TAG_ID = "id";
    static final String TAG_NAME = "name";
    static final String TAG_DESCRIPTION = "description";
    static final String TAG_IMAGEPATH = "imagepath";
    static final String TAG_SONGS_COUNT = "songs_count";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_category);
        cd = new ConnectionDetector(getApplicationContext());
        // Check for internet connection
        if (!cd.isConnectingToInternet()) {
            // Internet Connection is not present
            alert.showAlertDialog(CategoryActivity.this, "Internet Connection Error",
                    "Please connect to working Internet connection", false);
            // stop executing code by return
            return;
        }
        // Hashmap for ListView
        albumsList = new ArrayList<HashMap<String, String>>();
        // Loading Albums JSON in Background Thread
        new LoadCategories().execute();
        // get listview
        ListView lv = getListView();

        /**
         * Listview item click listener
         * TrackListActivity will be lauched by passing album id
         * */
        lv.setOnItemClickListener(new android.widget.AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> arg0, View view, int arg2,
                    long arg3) {
                // on selecting a single album
                // TrackListActivity will be launched to show tracks inside the album
                Intent i = new Intent(getApplicationContext(), ProductListActivity.class);
                // send album id to tracklist activity to get list of songs under that album
                String album_id = ((TextView) view.findViewById(R.id.album_id)).getText().toString();
                i.putExtra("album_id", album_id);           
                startActivity(i);
            }
        }); 
    }

    /**
     * Background Async Task to Load all Albums by making http request
     * */
    class LoadCategories extends AsyncTask<String, String, String> {

        /**
         * Before starting background thread Show Progress Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(CategoryActivity.this);
            pDialog.setMessage("Loading Please Wait ...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }

        /**
         * getting Albums JSON
         * */
        protected String doInBackground(String... args) {
            // Building Parameters
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            // getting JSON string from URL
            String json = jsonParser.makeHttpRequest(URL_ALBUMS, "GET",
                    params);
            // Check your log cat for JSON reponse
            Log.d("Albums JSON: ", "> " + json);
            try {               
                albums = new JSONArray(json);
                if (albums != null) {
                    // looping through All albums
                    for (int i = 0; i < albums.length(); i++) {
                        JSONObject c = albums.getJSONObject(i);

                        // Storing each json item values in variable
                        String id = c.getString(TAG_ID);
                        String name = c.getString(TAG_NAME);
                        String description = c.getString(TAG_DESCRIPTION);
                        String imageurl = c.getString(TAG_IMAGEPATH);
                        String songs_count = c.getString(TAG_SONGS_COUNT);
                        // creating new HashMap
                        HashMap<String, String> map = new HashMap<String, String>();
                        // adding each child node to HashMap key => value
                        map.put(TAG_ID, id);
                        map.put(TAG_NAME, name);
                        map.put(TAG_DESCRIPTION, description);
                        map.put(TAG_IMAGEPATH,imageurl);
                        map.put(TAG_SONGS_COUNT, songs_count);
                        // adding HashList to ArrayList
                        albumsList.add(map);
                    }
                }else{
                    Log.d("Albums: ", "null");
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
            return null;
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after getting all albums
            pDialog.dismiss();
            // updating UI from Background Thread
            runOnUiThread(new Runnable() {
                public void run() {
                    /**
                     * Updating parsed JSON data into ListView
                     * */
                    ListAdapter adapter = new SimpleAdapter(
                            CategoryActivity.this, albumsList,
                            R.layout.list_item_categories, new String[] 
                                    {
                                    TAG_ID, TAG_NAME, TAG_DESCRIPTION, TAG_IMAGEPATH, TAG_SONGS_COUNT 
                                    }, 
                                    new int[] 
                                    {
                                    R.id.album_id, R.id.album_name, R.id.album_description, R.id.list_image, R.id.songs_count 
                                    }
                            );
                    // updating listview
                    setListAdapter(adapter);
                }
            });         
        }
    }
}
4

1 回答 1

2

不用担心

我想你必须使用下面的代码，它对你很有用，几天前我在我的应用程序中使用了它：

首先将 onPostExecute 替换为：

    protected void onPostExecute(String file_url) {

            /**
             * Updating parsed JSON data into ListView
             * */
            adapter = new LazyAdapter(
                    CategoryActivity.this, albumsList);
            // updating listview
            setListAdapter(adapter);
            // updating UI from Background Thread
            pDialog.dismiss();

        }

现在创建一个 LazyAdapter 类并放入下面的代码，只需要复制和粘贴我已经以您的方式更改了它：

     public class LazyAdapter extends BaseAdapter {

private Activity activity;
private ArrayList<HashMap<String, String>> data;
private static LayoutInflater inflater=null;
public ImageLoader imageLoader; 

public LazyAdapter(Activity a, ArrayList<HashMap<String, String>> d) {
    activity = a;
    data=d;
    inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    imageLoader=new ImageLoader(activity.getApplicationContext());
}

public int getCount() {
    return data.size();
}

public Object getItem(int position) {
    return position;
}

public long getItemId(int position) {
    return position;
}

public View getView(int position, View convertView, ViewGroup parent) {
    View vi=convertView;
    if(convertView==null)
        vi = inflater.inflate(R.layout.listrow, null);

    TextView title = (TextView)vi.findViewById(R.id.title); 
    TextView description = (TextView)vi.findViewById(R.id.description); 
    TextView cost = (TextView)vi.findViewById(R.id.cost); 
    ImageView thumb_image=(ImageView)vi.findViewById(R.id.list_image); 


    HashMap<String, String> item = new HashMap<String, String>();
    item = data.get(position);

    // Setting all values in listview
    title.setText(item.get(Catalogue.KEY_TITLE));
    description.setText(item.get(Catalogue.KEY_DESCRIPTION));
    cost.setText(item.get(Catalogue.KEY_COST));

    imageLoader.DisplayImage(item.get(Catalogue.KEY_THUMB_URL), thumb_image);
    return vi;
}
}

快乐......快乐编码快乐结局

于 2013-02-01T09:58:39.053 回答