国际化 Java 应用程序时出错

我正在研究一个使用类ResourceBundle和ListResourceBundle.

该示例演示了如何使用名为 SampleRB 的资源包。

编译后我不断收到错误：

Английская версия программы: 
Exception in thread "main" java.lang.NullPointerException
    at java.util.ListResourceBundle.loadLookup(ListResourceBundle.java:202)
    at java.util.ListResourceBundle.handleGetObject(ListResourceBundle.java:130)
    at java.util.ResourceBundle.getObject(ResourceBundle.java:441)
    at java.util.ResourceBundle.getString(ResourceBundle.java:407)
    at LRBDemo.LRBDemo.main(LRBDemo.java:12)

该程序本身由LRBDemo类和主启动方法组成：

public class LRBDemo {
    public static void main(String[] args) {
        // загрузить комплект ресурсов по умолчанию
        ResourceBundle rd = ResourceBundle.getBundle("LRBDemo.SampleRB");

        System.out.println("Английская версия программы: ");
        System.out.println("Строка по ключу Title: " + rd.getString("title"));
        System.out.println("Строка по ключу StopText: " + rd.getString("StopText"));
        System.out.println("Строка по ключу StartText: " + rd.getString("StartText"));

        // загрузить комплект ресурсов для поддержки немецкого языка
        rd = ResourceBundle.getBundle("LRBDemo.SampleRBde", Locale.GERMAN);

        System.out.println("\nНемецкая версия программы: ");
        System.out.println("Строка для ключа Title: " + rd.getString("title"));
        System.out.println("Строка по ключу StopText: " + rd.getString("StopText"));
        System.out.println("Строка по ключу StartText: " + rd.getString("StartText"));
    }
}

具有英语语言支持的SampleRB类：

public class SampleRB extends ListResourceBundle {
    protected Object[][] getContents() {
        Object[][]  resources = new Object[3][2];

        resources[0][0] = "title";
        resources[0][1] = "MyProgram";

        resources[1][0] = "StopText";
        resources[1][1] = "Stop";

        resources[1][0] = "StartText";
        resources[2][1] = "Start";

        return resources;
    }
}

以及具有德语支持的SampleRBde类：

public class SampleRBde extends ListResourceBundle {
    protected Object[][] getContents() {
        Object[][] resources = new Object[3][2];

        resources[0][0] = "title";
        resources[0][1] = "Mein Programm";

        resources[1][0] = "StopText";
        resources[1][1] = "Anschlag";

        resources[2][0] = "StartText";
        resources[2][1] = "Anfang";

        return resources;
    }
}

代码本身不会显示错误，但是如果我在LRBDemoResourceBundle rd = ResourceBundle.getBundle("LRBDemo.SampleRB")类中以这种方式ResourceBundle rd = ResourceBundle.getBundle("SampleRB")而不是字符串而不是rd = ResourceBundle.getBundle("LRBDemo.SampleRBde", Locale.GERMAN);这样编写rd = ResourceBundle.getBundle("SampleRBde", Locale.GERMAN);，也就是说，我删除了类包，那么我得到了输出：

Exception in thread "main" java.util.MissingResourceException: Can't find bundle for base name SampleRB, locale ru_RU
    at java.util.ResourceBundle.throwMissingResourceException(ResourceBundle.java:1564)
    at java.util.ResourceBundle.getBundleImpl(ResourceBundle.java:1387)
    at java.util.ResourceBundle.getBundle(ResourceBundle.java:773)
    at LRBDemo.LRBDemo.main(LRBDemo.java:9)

我的项目结构：

对于如何消除错误并最终显示结果的建议，我将不胜感激。