Android部件nullpointexception

我正在JSON.I解析JSON，我可以顯示我的JSON列表視圖（圖像和文本），也成功創建了部件，我想在我的widget中顯示我的JSON的第一項標題。此代碼（如果我刪除小部件，然後我可以顯示小部件的第一個標題），但一段時間後，當我點擊小部件的按鈕，我有nullPointExcetpion 我做錯了什麼？Android部件nullpointexception

public class BriWidget extends AppWidgetProvider { 
public static String CLOCK_WIDGET_UPDATE = "CLOCK_WIDGET_UPDATE"; 
RemoteViews remoteViews; 
int appWidgetId; 
public File file; 
public Bitmap bitmap; 

@Override 
public void onDeleted(Context context, int[] appWidgetIds) { 
    Toast.makeText(context, "TimeWidgetRemoved id(s):" + appWidgetIds, 
      Toast.LENGTH_SHORT).show(); 
    super.onDeleted(context, appWidgetIds); 
} 

@Override 
public void onUpdate(Context context, AppWidgetManager appWidgetManager, 
     int[] appWidgetIds) { 
    super.onUpdate(context, appWidgetManager, appWidgetIds); 
    ComponentName thisWidget = new ComponentName(context, BriWidget.class); 
    for (int widgetId : appWidgetManager.getAppWidgetIds(thisWidget)) { 

     Intent intent = new Intent(context, SpleshScreen.class); 
     PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, 
       intent, 0); 
     remoteViews = new RemoteViews(context.getPackageName(), 
       R.layout.widget_demo1); 
     remoteViews 
       .setOnClickPendingIntent(R.id.widgetbtn, pendingIntent); 
     remoteViews 
       .setOnClickPendingIntent(R.id.widgetImage, pendingIntent); 
     remoteViews.setOnClickPendingIntent(R.id.widgetdesc, pendingIntent); 
     remoteViews.setOnClickPendingIntent(R.id.widgetbtn, 
       buildButtonPendingIntent1(context)); 
     remoteViews.setTextViewText(R.id.widgetdesc, getDesc()); 
     appWidgetManager.updateAppWidget(widgetId, remoteViews); 
    } 
} 

@Override 
public void onAppWidgetOptionsChanged(Context context, 
     AppWidgetManager appWidgetManager, int appWidgetId, 
     Bundle newOptions) { 

    Toast.makeText(context, "onAppWidgetOptionsChanged() called", 
      Toast.LENGTH_SHORT).show(); 
} 

public static PendingIntent buildButtonPendingIntent1(Context context) { 

    Intent intent = new Intent(); 
    intent.setAction(WidgetUtils.WIDGET_UPDATE_ACTION); 
    return PendingIntent.getBroadcast(context, 0, intent, 
      PendingIntent.FLAG_UPDATE_CURRENT); 
} 

private static CharSequence getDesc() { 
    return "this is a widget example"; 
} 

public static void pushWidgetUpdate(Context context, RemoteViews remoteViews) { 
    ComponentName myWidget = new ComponentName(context, BriWidget.class); 
    AppWidgetManager manager = AppWidgetManager.getInstance(context); 
    manager.updateAppWidget(myWidget, remoteViews); 
}

}

public class MyWidgetIntentReceiver extends BroadcastReceiver { 



@Override 
public void onReceive(Context context, Intent intent) { 
    PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE); 
    PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "YOUR TAG"); 

    wl.acquire(); 

    RemoteViews remoteViews = new RemoteViews(context.getPackageName(), 
      R.layout.widget_demo1); 
    remoteViews.setTextViewText(R.id.widgetdesc, getDesc("")); 
    remoteViews.setOnClickPendingIntent(R.id.widgetbtn, 
      BriWidget.buildButtonPendingIntent1(context)); 

    BriWidget 
      .pushWidgetUpdate(context.getApplicationContext(), remoteViews); 
    ComponentName thiswidget = new ComponentName(context, BriWidget.class); 
    AppWidgetManager manager = AppWidgetManager.getInstance(context); 
    manager.updateAppWidget(thiswidget, remoteViews); 

    wl.release(); 

} 
public void setOnetimeTimer(Context context){ 
    AlarmManager am=(AlarmManager)context.getSystemService(Context.ALARM_SERVICE); 
    Intent intent = new Intent(context, MyWidgetIntentReceiver.class); 
    PendingIntent pi = PendingIntent.getBroadcast(context, 0, intent, 0); 
    am.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), pi); 
} 


private String getDesc(String abc) { 
    abc = (MainActivity.itemList.get(0).get(MainActivity.KEY_title)) 
      .toString(); 

    return abc; 
}

}

公共類BRIgeAdapter延伸BaseAdapter {

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

private int screenSize; 

public BRIgeAdapter(Context context, ArrayList<HashMap<String, String>> d, 
     int screenSize) { 
    this.mContext = context; 
    this.data = d; 
    this.screenSize = screenSize; 
    inflater = (LayoutInflater) mContext 
      .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
    imageLoader = new ImageLoader(context.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.list_row, null); 

    TextView journal = (TextView) vi.findViewById(R.id.smalljournal); 
    TextView title = (TextView) vi.findViewById(R.id.smalltitle); 
    TextView description = (TextView) vi 
      .findViewById(R.id.smallDescription); 
    ImageView thumb_image = (ImageView) vi.findViewById(R.id.smallthumb); 
    TextView statId = (TextView) vi.findViewById(R.id.smallstatID); 
    TextView DateTime = (TextView) vi.findViewById(R.id.smallDateTime); 
    HashMap<String, String> itemList = new HashMap<String, String>(); 
    itemList = data.get(position); 

    journal.setText(itemList.get(MainActivity.KEY_journal)); 
    statId.setText(itemList.get(MainActivity.KEY_statID)); 


    String titleString = itemList.get(MainActivity.KEY_title); 

    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); 

    String DateTimeTxt = itemList.get(MainActivity.KEY_pubDate).replace(
      "T", " "); 

    try { 
     Date _d = df.parse(DateTimeTxt); 
     SimpleDateFormat new_df = new SimpleDateFormat("dd.MM.yyyy"); 
     String _s = new_df.format(_d); 
     DateTime.setText(_s); 
    } catch (ParseException e) { 

     e.printStackTrace(); 
    } 

    if (screenSize == Configuration.SCREENLAYOUT_SIZE_NORMAL) 
     description.setVisibility(View.INVISIBLE); 

    else 
     description.setVisibility(View.VISIBLE); 
    title.setText(titleString); 

    description.setText(itemList.get(MainActivity.KEY_description)); 


    String url = itemList.get(MainActivity.KEY_image); 

    imageLoader.DisplayImage(url, thumb_image); 

    return vi; 
}

}

public class MainActivity extends Activity { 
public String URL = "***********************"; 

public static String KEY_title = "title"; 
public static String KEY_description = "description"; 
public static String KEY_image = "image"; 
public static String KEY_journal = "journal"; 
public static String KEY_JournalID = "JournalID"; 
public static String KEY_pubDate = "pubDate"; 
public static String KEY_statID = "statID"; 
public JSONArray jsonarray; 
public ListView list; 
public JSONParser jsonparser; 
static BRIgeAdapter adapter; 

public static ArrayList<HashMap<String, String>> itemList; 
public ImageLoader imageLoader; 
static final int DIALOG_ERROR_CONNECTION = 1; 

private ArrayList<Content> contents = new ArrayList<Content>(); 

public TransparentProgressDialog pd; 
public HashMap<String, String> map; 
public Tools tools; 

private int screenSize; 

public LoadDataAllChanelsToServer loadData; 

private ConnectionDetector cd; 

@SuppressLint("CutPasteId") 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    setContentView(R.layout.main); 
    screenSize = getResources().getConfiguration().screenLayout 
      & Configuration.SCREENLAYOUT_SIZE_MASK; 

    itemList = new ArrayList<HashMap<String, String>>(); 
    list = (ListView) findViewById(R.id.listView1); 
    cd = new ConnectionDetector(getApplicationContext()); 
    adapter = new BRIgeAdapter(MainActivity.this, itemList, screenSize); 

    Thread.setDefaultUncaughtExceptionHandler(new UnCaughtException(this, 
      this)); 
    loadData = new LoadDataAllChanelsToServer(); 

    pd = new TransparentProgressDialog(this, R.drawable.loader); 

    loadData.execute(); 

} 

private class LoadDataAllChanelsToServer extends 
     AsyncTask<String, Integer, String> { 

    @Override 
    protected void onPreExecute() { 

     pd.show(); 
    } 

    @Override 
    protected String doInBackground(String... urls) { 

     jsonparser = new JSONParser(); 

     JSONObject jsonobject = jsonparser.getJSONfromURL(URL); 
     try { 

      jsonarray = jsonobject.getJSONArray("data"); 

      for (int i = 0; i < jsonarray.length(); i++) { 
       jsonobject = jsonarray.getJSONObject(i); 

       map = new HashMap<String, String>(); 

       map.put("journal", jsonobject.getString(KEY_journal)); 
       map.put("image", jsonobject.getString(KEY_image)); 
       map.put("title", jsonobject.getString(KEY_title)); 
       map.put("description", 
         jsonobject.getString(KEY_description)); 
       map.put("JournalID", jsonobject.getString(KEY_JournalID)); 
       map.put("pubDate", jsonobject.getString(KEY_pubDate)); 
       map.put("statID", jsonobject.getString(KEY_statID)); 

       Content cont = new Content(jsonobject.getString("journal"), 
         jsonobject.getString("image"), 
         jsonobject.getString("title"), 
         jsonobject.getString("pubDate"), 
         jsonobject.getString("description"), 
         jsonobject.getString("JournalID"), 
         jsonobject.getString("statID")); 
       contents.add(cont); 

       itemList.add(map); 

      } 

     } catch (JSONException e) { 
      Log.e("Error", e.getMessage()); 
      e.printStackTrace(); 
     } 

     return itemList.toString(); 

    } 

    @Override 
    protected void onPostExecute(String result) { 
     try { 
      if (pd != null) { 
       pd.dismiss(); 

      } 
     } catch (Exception e) { 

     } 

     try { 
      adapter = new BRIgeAdapter(MainActivity.this, itemList, 
        screenSize); 
      list.setAdapter(adapter); 

     } catch (NullPointerException e) { 
      e.printStackTrace(); 
     } 

    } 

}

}

後的一段時間，我有nullpointexception在MyWidgetIntentReceiver類getDesc方法 ABC =（MainActivity.itemList.get（0）獲得（MainActivity.KEY_title））的ToString（）; 是空

來源

2014-02-13 user3293990

顯示你的logcat – rajshree

是的，我用logcat和nullpointexception是MyWidgetIntentReceiver getDesc方法 – user3293990

粘貼你的logcat像你發佈你的代碼的問題。 – InnocentKiller

它是不是安全的單行用這麼多點，嘗試更換

abc = (MainActivity.itemList.get(0).get(MainActivity.KEY_title)) 
      .toString();

有：

if (MainActivity.itemList != null && MainActivity.itemList.size() > 0) { 

      HashMap<String, String> listItem = MainActivity.itemList.get(0); 

      if (listItem != null) { 
       adb = listItem.get(MainActivity.KEY_title); 
      } 
     }

和調試到以找出哪些對象爲空。

順便說一句，在Activity中使用靜態ArrayList對象是一個壞主意，Activity的靜態數據將被系統GC清除，使用startActivityForResult（）從Activity中獲取數據。

來源

2014-02-13 10:13:23 herbertD

謝謝你我會嘗試你的代碼..（在Activity中使用靜態的ArrayList對象是一個壞主意。）我怎麼能解決（改變它）？ – user3293990

此代碼工作。但如果我關閉應用tittle爲null nothink – user3293990

使用startActivityForResult（）從Activity獲取數據。 – herbertD

Android部件nullpointexception

回答

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