SimpleExpandableListAdapter上的notifyDataSetChanged（）在广播接收器中不工作

我已经通过了Android: How to correctly use NotifyDataSetChanged with SimpleExpandableListAdapter?，并且具有类似的程序结构，但创建（第一次扫描）时出现（接入点）列表并且在下一次无线扫描时消失。SimpleExpandableListAdapter上的notifyDataSetChanged（）在广播接收器中不工作

public class APScanActivity extends ExpandableListActivity { 

    public static WifiManager mywifiManager; 
    private TextView PlotTitle; 
    boolean mDualPane; 
    int mCurCheckPosition = 0; 
    List<ScanResult> scanResults; 
    SimpleExpandableListAdapter expListAdapter; 
    ExpandableListView APList; 

    List GroupList = new ArrayList(); 
    List ChildList = new ArrayList(); 

    int scanResultsSize; 
    ArrayList<String> NetworkList; 
    Multimap<String,String> Networks; 
    private long[] expandedIds; 

    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     mywifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE); 
     setContentView(R.layout.activity_autoscan); 
     APList = getExpandableListView(); 
     PlotTitle = (TextView) findViewById(R.id.displayMsg); 

     View detailsFrame = findViewById(R.id.detailFragment); 
     mDualPane = detailsFrame != null && detailsFrame.getVisibility() == View.VISIBLE; 

     if (savedInstanceState != null) { 
      // Restore last state for checked position. 
      mCurCheckPosition = savedInstanceState.getInt("curChoice", 0); 
     } 

     if (mDualPane) { 
      // In dual-pane mode, list view highlights selected item. 
      getExpandableListView().setChoiceMode(ExpandableListView.CHOICE_MODE_SINGLE); 
      showDetails(mCurCheckPosition,null); 
     } 

     if (mywifiManager.isWifiEnabled()) 
      PlotTitle.setText("Choose Accesspoint from Network list"); 
     registerReceiver(wifiScanReceiver, new IntentFilter(
      WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)); 
     new WifiScanner().execute();  
} 



/** Implement a background task for Wi-Fi scans **/ 
public static class WifiScanner extends AsyncTask<Void, Void, Boolean> { 
    protected Boolean doInBackground(Void... params) { 
     return mywifiManager.startScan(); 
    } 
} 
private BroadcastReceiver wifiScanReceiver = new BroadcastReceiver() { 
    @Override 

    public void onReceive(Context context, Intent intent) { 

     /** Get the Wi-Fi scan results **/ 
     scanResults = mywifiManager.getScanResults(); 
     new WifiScanner().execute(); 
     scanResultsSize = (scanResults == null) ? 0 : scanResults 
       .size(); 
     Networks = ArrayListMultimap.create(); // This is our multimap with ssid,bssid pairs 

     for (int index = 0; index < scanResultsSize; index++) { 
      ScanResult scanResult = scanResults.get(index); 
      String ssid = scanResult.SSID; 
      String AccessPoint = scanResult.BSSID+" ("+scanResult.level+"dBm)"; 

      Networks.put(ssid, AccessPoint);    

     } 

     NetworkList = new ArrayList<String>(Networks.keySet()); 

     GroupList.clear(); 
     ChildList.clear(); 

     GroupList = createGroupList(); 
     ChildList = createChildList(); 

     if (expListAdapter == null){ 
      expListAdapter = new SimpleExpandableListAdapter(
        context, 
        GroupList,    // Creating group List. 
        R.layout.group_row,    // Group item layout XML. 
        new String[] { "Network" }, // the key of group item. 
        new int[] { R.id.row_name }, // ID of each group item.-Data under the key goes into this TextView. 
        ChildList,    // childData describes . 
        R.layout.child_row,    // Layout for sub-level entries(second level). 
        new String[] {"AccPt"},  // Keys in childData maps to. 
        new int[] { R.id.grp_child}  // Data under the keys above go into these TextViews. 
       ); 

      //setListAdapter(expListAdapter); 
      APList.setAdapter(expListAdapter); 
     } 
     expListAdapter.notifyDataSetChanged(); 
    } 
}; 

    @SuppressWarnings({ "unchecked", "rawtypes" }) 
    public List createGroupList() { 
      ArrayList result = new ArrayList(); 
      for(int i = 0 ; i < NetworkList.size() ; ++i) { 
       HashMap m = new HashMap(); 
       m.put("Network",NetworkList.get(i)); // the key and it's value. 
       result.add(m); 
      } 

      return (List)result; 
    } 

    @SuppressWarnings({ "unchecked", "rawtypes" }) 
    public List createChildList() { 

      ArrayList result = new ArrayList(); 
      for(int i = 0 ; i < NetworkList.size() ; ++i) { 
       /* each group need one HashMap-Here for each group we have subgroups */ 
       String nn = NetworkList.get(i); 
       ArrayList<String> APlist = new ArrayList<String>(Networks.get(nn)); 
       ArrayList secList = new ArrayList(); 

       for(int n = 0 ; n < APlist.size() ; n++) { 
       HashMap child = new HashMap(); 
       String AP = APlist.get(n); 
       child.put("AccPt", AP); 
       secList.add(child); 
       } 
      result.add(secList); 
      } 

      return result; 
    }

我无法弄清楚数据更新如何被通知到适配器。与arraylist适配器不同，SimpleExpandableListAdapter上没有直接添加/删除等方法。

来源

2013-07-23 essgee