无法以 null 启动服务 [服务名称]

我最近编写了一个 Android Widget 并在模拟器和我的 Galaxy S 上进行了测试，它在两者上都运行良好，在我将其发布到 Android 市场后，现在我收到了一些错误报告。

我在 Widget 类的 onUpdate 中声明一个服务，如下所示：

if (appWidgetIds != null) {
    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++) {
        // Start Service for each instance
        int appWidgetId = appWidgetIds[i];
        Intent active = new Intent(context, DialerService.class);
        active.setAction("Start");
        active.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID,
                appWidgetId);

        context.startService(active);
    }
}

有些人遇到的错误是：

java.lang.RuntimeException: Unable to start service dialer.impact.DialerService@45f926f0 with null: java.lang.NullPointerException
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3282)
at android.app.ActivityThread.access$3600(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2211)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:144)
at android.app.ActivityThread.main(ActivityThread.java:4937)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
**at dialer.impact.DialerService.onStart(DialerService.java:18)**
at android.app.Service.onStartCommand(Service.java:420)
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3267)
... 10 more

错误状态为NullPointerException在第 18 行ServiceClass这是：

@Override
public void onStart(Intent intent, int startId) {
    //Line 18th 
            String command = intent.getAction();
    int appWidgetId = intent.getExtras().getInt(
            AppWidgetManager.EXTRA_APPWIDGET_ID);
    RemoteViews remoteView = new RemoteViews(getApplicationContext()
            .getPackageName(), R.layout.main);
    AppWidgetManager appWidgetManager = AppWidgetManager
            .getInstance(getApplicationContext());
}

18号线是String command = intent.getAction();

意图无效的原因可能是什么 请帮忙

根据文档onStart() http://developer.android.com/reference/android/app/Service.html#onStart(android.content.Intent,%20int)（实际上onStartCommand()但参数是相同的）：

intent如给定的，提供给 startService(Intent) 的 Intent。这可能为空如果服务在其进程消失后重新启动，并且之前返回了除 START_STICKY COMPATIBILITY 之外的任何内容。