0

大家好，我在使用 NULL POINTER EXCEPTION 时遇到了一些问题。只有当我第一次将小部件放在主屏幕时才会出现错误。每隔一段时间小部件都能正常工作。小部件具有配置活动。此活动不会启动，而是调用小部件提供程序中的 onReceive 并通过 NULL POINTER EXCEPTION。任何人都可以为我的问题提供一个好的解决方案吗？

我附上了配置活动和小部件提供程序类的代码。

小部件配置类：

public class SingleNoteConfigure extends ListActivity  {


private NotesDbAdapter mDbHelper;
int mAppWidgetId = AppWidgetManager.INVALID_APPWIDGET_ID;
public static String ACTION_WIDGET_LIST = "ActionReceiverList";
public static String ACTION_WIDGET_NEW = "ActionReceiverNew";



@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    //set the result to canceled to allow the user
    //to change their mind mid widget configure
    setResult(RESULT_CANCELED);
    Log.d("MYTAG", "in the onCreate of of the widget configure");

    //set the layout file for the widget configure
    setContentView(R.layout.notes_list_config);

    //using the action bar title for user instruction
    setTitle("Select note to display on the wodget");

    // Find the widget id from the intent. 
    Intent intent = getIntent();
    Bundle extras = intent.getExtras();
    if (extras != null) {
        mAppWidgetId = extras.getInt(
                AppWidgetManager.EXTRA_APPWIDGET_ID, AppWidgetManager.INVALID_APPWIDGET_ID);
    }
    Log.d("MYTAG", "in the onCreate");
    //stuff to get the database to open
    mDbHelper = new NotesDbAdapter(this);
    mDbHelper.open();

    //call the method that fills the list view
    fillData();

}

 @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);

        Cursor note = mDbHelper.fetchNote(id);
        startManagingCursor(note);
        String title = note.getString(note.getColumnIndexOrThrow(NotesDbAdapter.KEY_TITLE));
        String text = note.getString(note.getColumnIndexOrThrow(NotesDbAdapter.KEY_BODY));



        RemoteViews views = new RemoteViews(this.getPackageName(), R.layout.singlenote_widget);
        AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(this); 
        appWidgetManager.updateAppWidget(mAppWidgetId, views);    



        Log.d("MYTAG", "in the onListItemClick....");

        loadData(title, text, id);//here id is the row id of the selection;it is returned by the onListItemSelect 

        Intent resultValue = new Intent();
        resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, mAppWidgetId);            
        setResult(RESULT_OK,resultValue);   
        finish();
 }



 void loadData(String title, String text, Long Id) {

    AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(this); 
    Log.d("MYTAG", "in the load data....");
    SingleNote.updateWidget(this, appWidgetManager, mAppWidgetId, title, text);
    NotesDbAdapter.updateWidgetId(mAppWidgetId,Id);

}

private void fillData() {
    Cursor notesCursor = mDbHelper.fetchAllNotes();
    startManagingCursor(notesCursor);
    Log.d("MYTAG", "in the fill data  of the widget configure");
    // Create an array to specify the fields we want to display in the list (TITLE and DATE)
    String[] from = new String[]{NotesDbAdapter.KEY_TITLE,NotesDbAdapter.KEY_DATE};


    // and an array of the fields we want to bind those fields to (title and date)
    int[] to = new int[]{R.id.title,R.id.date};


    // Now create a simple cursor adapter and set it to display
    SimpleCursorAdapter notes = new SimpleCursorAdapter(this, R.layout.notes_row1, notesCursor, from, to);

    setListAdapter(notes);


}  
}

小部件提供类：

public class SingleNote extends AppWidgetProvider {

public static String UPDATE_ACTION = "ActionUpdateSinglenoteWidget";

private static NotesDbAdapter mDbHelper;



public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
    final int N = appWidgetIds.length;

    // Perform this loop procedure for each App Widget that belongs to this provider
    for (int i=0; i<N; i++) {
        int appWidgetId = appWidgetIds[i];            

        Log.d("MYTAG", "in the onUpdate");

        Intent intent = new Intent(context, Notepadv3.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);
        RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.singlenote_widget);
        views.setOnClickPendingIntent(R.id.single_note_text, pendingIntent);  

        // Push update for this widget to the home screen

        ComponentName thisWidget = new ComponentName(context, SingleNote.class);
        AppWidgetManager manager = AppWidgetManager.getInstance(context);
        manager.updateAppWidget(thisWidget, views);

    }
}

@Override 
public void onReceive(Context context, Intent intent) { 
    Log.d("MYTAG", "in the onReceive....");
        String action = intent.getAction(); 
        Log.d("MYTAG", "in the onReceive....line 2");
        Bundle extras = intent.getExtras(); 
        Log.d("MYTAG", "in the onReceive....after bundle");//THis gets in the log 
        String title = extras.getString("title");
        Log.d("MYTAG", "in the onReceive....after title");//Non of the other log entry's
                                                          // make it in 
        String text = extras.getString("body");
        Log.d("MYTAG", "in the onReceive....after text");
        Log.d("MYTAG", "@ the point of int");
        int id = extras.getInt("widget_id");

        Log.d("MYTAG", action+ title + text + id);

        if (action != null && action.equals(UPDATE_ACTION)) { 
            final AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context); 

            if (id > 0)
            {
                updateWidget(context, appWidgetManager, id ,title ,text);
            }
            else {
                return;

            }
    } 

    else { 
            super.onReceive(context, intent); 
    } 


}

static void updateWidget(Context context, AppWidgetManager appWidgetManager, int appWidgetId, String title, String text){

    Log.d("MYTAG", "in the updatewidget method in the siglenote widget....");
    RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.singlenote_widget);
    views.setTextViewText(R.id.single_note_title, title);
    views.setTextViewText(R.id.single_note_text, text);
    appWidgetManager.updateAppWidget(appWidgetId, views);



}
}

如您所见，我到处都有日志条目，并且我在日志条目结束的地方发表了评论。

此方法在其中一个活动中，我调用它来根据需要更新我的小部件。我在方法的末尾有一个“if(!null)”，这样就不会得到 NULL POINTER EXCEPTION ，但这似乎没有帮助

private void updateWidget() { 
    Cursor note = mDbHelper.fetchWidgetId(mRowId);
    startManagingCursor(note);
    Log.d("MYTAG", "in the updatewidget method in edit note");
    int id = note.getInt(note.getColumnIndexOrThrow(NotesDbAdapter.KEY_WIDGET_ID));//here id is the widget id we get out of the database
    Intent i = new Intent(this, SingleNote.class); 
    i.setAction(SingleNote.UPDATE_ACTION); 
    i.putExtra("title", mTitleText.getText().toString());
    i.putExtra("body", mBodyText.getText().toString());
    i.putExtra("widget_id",id);
    String title = mTitleText.getText().toString();
    //String body =  mBodyText.getText().toString();
    if(title != null){ 
    sendBroadcast(i); 
    }

编辑堆栈跟踪：

    07-12 04:08:36.473: E/STACKTRACE_TAG(2615): STACKTRACE
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615): java.lang.NullPointerException
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at drkstr.yan.SingleNote.onReceive(SingleNote.java:58)
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at android.app.ActivityThread.handleReceiver(ActivityThread.java:1994)
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at android.app.ActivityThread.access$2400(ActivityThread.java:132)
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1093)
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at android.os.Handler.dispatchMessage(Handler.java:99)
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at android.os.Looper.loop(Looper.java:143)
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at android.app.ActivityThread.main(ActivityThread.java:4196)
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at java.lang.reflect.Method.invokeNative(Native Method)
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at java.lang.reflect.Method.invoke(Method.java:507)
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
    07-12 04:08:36.483: E/STACKTRACE_TAG(2615):     at dalvik.system.NativeStart.main(Native Method)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615): STACKTRACE
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615): java.lang.NullPointerException
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at drkstr.yan.SingleNote.onReceive(SingleNote.java:58)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at android.app.ActivityThread.handleReceiver(ActivityThread.java:1994)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at android.app.ActivityThread.access$2400(ActivityThread.java:132)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1093)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at android.os.Handler.dispatchMessage(Handler.java:99)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at android.os.Looper.loop(Looper.java:143)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at android.app.ActivityThread.main(ActivityThread.java:4196)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at java.lang.reflect.Method.invokeNative(Native Method)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at java.lang.reflect.Method.invoke(Method.java:507)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
    07-12 04:08:45.483: E/STACKTRACE_TAG(2615):     at dalvik.system.NativeStart.main(Native Method)

以下是我的主要问题： 1. 为什么只有在全新安装应用程序后第一次放置小部件时才会出现这种情况？2. 为什么在小部件配置之前调用onRecieve？3.最后我该如何解决。

感谢您花时间阅读本文以及您可以提供的任何帮助。

4

1 回答 1

1

你应该注意的主要事情是你有一个NullPointerExceptionat SingleNote.java:58。

从您对日志中显示哪些语句的评论来看，我猜这extras是空的，这意味着Intent 中没有额外内容。如果它只发生在第一次，那是有道理的。在使用它之前对附加功能进行空检查。

于 2013-07-11T19:45:44.170 回答