为什么roboguice不会开始我的领域？

Question

我看到了tutorial

并且我不确定为什么roboguice不会初始化PhoneDal？

public class OutgoingCallReceiver extends BroadcastReceiver {

    @Inject private CommentDal commentDal;
    @Inject private PhoneDal phoneDal;

    @Override
    public void onReceive(final Context context, final Intent intent) {
        Log.v(Constants.LOGGER_TAG, "OutgoingCallReceiver onReceive");
        if (intent.getAction()
                .equals(OutgoingCallReceiver.OUTGOING_CALL_ACTION)) {

            Log.v(Constants.LOGGER_TAG,
                    "OutgoingCallReceiver NEW_OUTGOING_CALL received");

            String phoneNumber = intent.getExtras().getString(
                    OutgoingCallReceiver.INTENT_PHONE_NUMBER);

            if (isBlocked(phoneNumber))
            {
                setResultData(null);
                Intent i = new Intent(context, PopupActivity.class);
                i.putExtra(Constants.DIALED_PHONE, phoneDal.getItem(phoneNumber));
                i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                context.startActivity(i);
            }
        }
    }

    private boolean isBlocked(String phoneNumber) {
        Phone phone = phoneDal.getItem(phoneNumber);
        boolean ans;
        if (phone != null && phone.isBlocked == false)
        {
            ans = true;
        }
        else
        {
            ans = false;
        }

        return ans;
    }
}

在这一行中，它在运行时属于NPE： Phone phone = phoneDal.getItem(phoneNumber);

我必须先拨打guice.getInjectedElement(type)吗？