在ListView中更改圖像（使用簡單適配器）

Question

我正在按照this鏈接的教程創建一個包含數據庫數據的列表視圖。它包含一張圖片（默認情況下 - 關閉燈泡）和兩個文本 - 數據庫記錄的名稱（房間）和狀態（開/關）。在從數據庫加載數據的AsyncTask結束時，我想要掃描列表並更改狀態等於「1」的每個位置的圖片以打開燈泡。

但圖像沒有改變。就好像listview不刷新一樣。

每一個幫助將不勝感激。

public class LightingActivity extends ListActivity { 

private ProgressDialog pDialog; 
JSONParser jParser = new JSONParser(); 
JSONArray status = null; 
ArrayList<HashMap<String, String>> statusList; 

private static String address_getall = "http://192.168.2.112/db_lighting_getall.php"; 
private static String address_update = "http://192.168.2.112/db_lighting_change.php"; 

private static final String SID_SUCCESS = "success"; 
private static final String SID_ARRAY = "Lighting"; 
private static final String SID_ID = "light_id"; 
private static final String SID_NAME = "name"; 
private static final String SID_STATUS = "value"; 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 
      WindowManager.LayoutParams.FLAG_FULLSCREEN); 
    setContentView(R.layout.lighting_activity); 

    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build(); 
    StrictMode.setThreadPolicy(policy); 

    statusList = new ArrayList<HashMap<String, String>>(); 

    new LoadData().execute(); 

    ListView lv = getListView(); 
    lv.setOnItemClickListener(new OnItemClickListener() { 

     @Override 
     public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
      // ...Listener... 
     } 
    }); 
} 

class LoadData extends AsyncTask<String, String, String> { 

    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 
     pDialog = new ProgressDialog(LightingActivity.this); 
     pDialog.setMessage("Downloading..."); 
     pDialog.setIndeterminate(false); 
     pDialog.setCancelable(false); 
     pDialog.show(); 
    } 

    protected String doInBackground(String... args) { 

     List<NameValuePair> params = new ArrayList<NameValuePair>(); 
     JSONObject json = jParser.makeHttpRequest(address_getall, "GET", params); 

     try { 
      int success = json.getInt(SID_SUCCESS); 
      if (success == 1) { 
       status = json.getJSONArray(SID_ARRAY); 
       for (int i = 0; i < status.length(); i++) { 
        JSONObject data = status.getJSONObject(i); 
        String light_id = data.getString(SID_ID); 
        String light_name = data.getString(SID_NAME); 
        String light_status = data.getString(SID_STATUS); 

        HashMap<String, String> map = new HashMap<String, String>(); 
        map.put(SID_ID, light_id); 
        map.put(SID_NAME, light_name); 
        map.put(SID_STATUS, light_status); 

        statusList.add(map); 
       } 
      } else { 
       // Error 
      } 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
     return null; 
    } 

    protected void onPostExecute(String file_url) { 

     pDialog.dismiss(); 
     runOnUiThread(new Runnable() { 
      public void run() { 
       ListAdapter adapter = new SimpleAdapter(
         LightingActivity.this, statusList, 
         R.layout.lighting_list, new String[]{SID_ID, SID_STATUS, SID_NAME}, 
         new int[]{R.id.light_id, R.id.light_status, R.id.light_name}); 
       setListAdapter(adapter); 

       // I tried doing it like this: 
       ListView lv = getListView(); 
       for (int i = 0; i < lv.getCount(); i++) { 
       View v = lv.getAdapter().getView(i, null, null); 
       TextView light_status = (TextView) v.findViewById(R.id.light_status); 
       String status = light_status.getText().toString(); 
       if (status.equals("1")) { 
       // Everything works till here - I checked with Toasts 
        ImageView img = (ImageView) v.findViewById(R.id.light_icon); 
        img.setImageResource(R.drawable.light_on); 
        lv.invalidateViews(); 
        lv.refreshDrawableState(); 
       } 
       } 
      } 
     }); 
    } 
} 

請寬容，我是新來的Java :)

Answer 1

有這麼多的事情錯在你的代碼，它是超越儲蓄！我建議你谷歌有關如何使用AsyncTask將數據加載到ListView。有很多例子。通過快速搜索，這看起來接近您的需求。

http://android-er.blogspot.gr/2010/07/load-listview-in-background-asynctask.html

短短指針

1) onPostExecute, onProgressUpdate and onPreExceute of AsyncTask are executed 
    in the UI thread so the runOnUiThread(new Runnable() {}) is not necessary. 
    Only the doInBackground method is executed in another thread; 

2) Put all the logic about what each rows shows like inside the getView method 
    of the adapter. 

3) To update the views of a listView you change the data in the ArrayList and then 
    call notifyDataSetChanged() on the ListView 's adapter. This causes all of the views 
    to be re-drawn. And because all the logic is in the getView method your views 
    are showing what the data contains.