Question

我正在尝试构建一个库，只要包含在应用程序项目中，它就会在系统托盘上弹出persistent notification。我做了一个正常的应用程序，并在运行完美的设备上测试它。现在，我已将该项目转换为库并将该库引用到android项目。

以下是我的MainActivity，它被命名为图书馆项目的SearchBar：

public class SearchBar extends Activity {

NotificationManager nm;
public static String PACKAGE_NAME;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.search_bar);

    PACKAGE_NAME = getApplicationContext().getPackageName();
}

public void searchBar() {

    Notification notification = new Notification(R.drawable.ic_stat_notify,
            "STest", System.currentTimeMillis());

    RemoteViews contentView = new RemoteViews(PACKAGE_NAME,
            R.layout.persistent_notification_layout);

    notification.contentView = contentView;

    Intent notificationIntent = new Intent();
    notificationIntent.setClassName("com.example.searchbar",
            "com.example.searchbar.SearchAutoSuggest");

    notificationIntent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP
            | Intent.FLAG_ACTIVITY_CLEAR_TOP);

    nm = (NotificationManager) getSystemService(SearchBar.NOTIFICATION_SERVICE);

    notification.flags |= Notification.FLAG_NO_CLEAR;
    notification.flags |= Notification.FLAG_ONGOING_EVENT;

    PendingIntent contentIntent = PendingIntent.getActivity(this, 2,
            notificationIntent, PendingIntent.FLAG_UPDATE_CURRENT);

    notification.contentIntent = contentIntent;

    nm.notify(AppSingleton.NOTIFICATION_ID_ALWAYS, notification);
}

}

而且，我正在将此库称为testProject's MainActivity，如下所示：

public class MainActivity extends Activity {

SearchBar notification;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    notification = new SearchBar();

    notification.searchBar();

}
}

现在，当我运行testProject时，我收到的错误是：

 Caused by: java.lang.IllegalStateException: System services not available to Activities before onCreate()
at android.app.Activity.getSystemService(Activity.java:4463)
at com.example.searchbar.SearchBar.searchBar(SearchBar.java:43)
at com.example.libtest.MainActivity.onCreate(MainActivity.java:19)

在：

nm = (NotificationManager) getSystemService(SearchBar.NOTIFICATION_SERVICE);

我尝试/搜索了几个东西，但是没有他们帮助我解决问题。我究竟做错了什么？任何形式的帮助将不胜感激。

Answer 1

同意@Karakuri aplly他的建议和这段代码尝试以下代码

nm = (NotificationManager) context.getSystemService(SearchBar.NOTIFICATION_SERVICE);

Answer 2

活动并不是要通过new关键字自行实例化。 Android操作系统应该这样做。以下是我要改变的内容：

没有SearchBar扩展Activity。
为SearchBar提供public方法（甚至可以是static方法），将Context作为参数。用它来获取NotificationManager实例。

喜欢这样

public class SearchBar {
    private SearchBar() {/* no instantiation */}

    public static void notifyPersistently(Context context) {
        NotificationManager nm = (NotificationManager)context.getSystemService(SearchBar.NOTIFICATION_SERVICE);
        // all the rest ...
    }
}

Answer 3

IllegalStateException：活动无法使用的系统服务在onCreate（）
之前

因为您正在SearchBar课程中扩展活动但未在AndroidManifest.xml中注册。

所以创建SearchBar类作为普通的java类而不扩展Activity并使用类构造函数将MainActivity上下文传递给SearchBar类，或者作为方法参数传递：

public class SearchBar {

NotificationManager nm;
public static String PACKAGE_NAME;
Context context;
 public  SearchBar(Context context) {
    this.context=context;
    PACKAGE_NAME = context.getPackageName();
}
....

当我尝试在库项目中使用getSystemService时获取java.lang.IllegalStateException

3 个答案: