Android小部件onReceive崩溃

Question

基本上，当我单击小部件上的特定按钮时，我想获取数据库中的下一条记录。当我在应用程序中使用它时，该功能本身可以正常工作。但是在小部件中它崩溃了。我认为问题出在 onReceive 函数本身，即使我只是将 onReceive 设置为更新文本视图，它也会作为 nullpointerexception 崩溃。

公共静态字符串 NEXT_RECORD = "next_record";

这里是调用它的地方：

Intent 意图 = new Intent(context, MyWidgetProvider.class);
意图.setAction(NEXT_RECORD);待定意图 待定意图 = PendingIntent.getBroadcast（上下文， 0，意图，PendingIntent.FLAG_UPDATE_CURRENT); remoteViews.setOnClickPendingIntent(R.id.TextView02, pendingIntent);

并在接收时

  @Override
  public void onReceive(Context context, Intent intent) {
   super.onReceive(context, intent);
   if(NEXT_RECORD.equals(intent.getAction())){
       newid = mDbHelper.getNextRecord(1, keyid);
    }

  }



04-12 14:47:57.591: E/AndroidRuntime(30633): FATAL EXCEPTION: main
04-12 14:47:57.591: E/AndroidRuntime(30633): java.lang.RuntimeException: Unable to start receiver com.example.app.hs.MyWidgetProvider: java.lang.NullPointerException
04-12 14:47:57.591: E/AndroidRuntime(30633):    at android.app.ActivityThread.handleReceiver(ActivityThread.java:2362)
04-12 14:47:57.591: E/AndroidRuntime(30633):    at android.app.ActivityThread.access$1500(ActivityThread.java:142)
04-12 14:47:57.591: E/AndroidRuntime(30633):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1284)
04-12 14:47:57.591: E/AndroidRuntime(30633):    at android.os.Handler.dispatchMessage(Handler.java:99)
04-12 14:47:57.591: E/AndroidRuntime(30633):    at android.os.Looper.loop(Looper.java:137)
04-12 14:47:57.591: E/AndroidRuntime(30633):    at android.app.ActivityThread.main(ActivityThread.java:4931)
04-12 14:47:57.591: E/AndroidRuntime(30633):    at java.lang.reflect.Method.invokeNative(Native Method)
04-12 14:47:57.591: E/AndroidRuntime(30633):    at java.lang.reflect.Method.invoke(Method.java:511)
04-12 14:47:57.591: E/AndroidRuntime(30633):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
04-12 14:47:57.591: E/AndroidRuntime(30633):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558)
04-12 14:47:57.591: E/AndroidRuntime(30633):    at dalvik.system.NativeStart.main(Native Method)
04-12 14:47:57.591: E/AndroidRuntime(30633): Caused by: java.lang.NullPointerException
04-12 14:47:57.591: E/AndroidRuntime(30633):    at com.example.app.hs.MyWidgetProvider.onReceive(MyWidgetProvider.java:100)

Answer 1

Caused by: java.lang.NullPointerException
    at com.example.app.hs.MyWidgetProvider.onReceive(MyWidgetProvider.java:100)

如果 newid = mDbHelper.getNextRecord(1, keyid); 抛出此 NPE，则 mDbHelper 为空。在尝试读取之前简单地实例化mDbHelper：

@Override
public void onReceive(Context context, Intent intent) {
    super.onReceive(context, intent);
    if (NEXT_RECORD.equals(intent.getAction())) {
        mDbHelper = new DbHelper(context); // I guessed at the constructor's parameters
        newid = mDbHelper.getNextRecord(1, keyid);
    }

}