### Question:
ResourceBundleHelper { @Nullable public static String getString (@Nullable final ResourceBundle aResourceBundle, @Nonnull @PropertyKey final String sKey) { if (aResourceBundle != null) try { return aResourceBundle.getString (sKey); } catch (final MissingResourceException ex) { } return null; } private  ResourceBundleHelper(); @Nullable static ResourceBundle getResourceBundle(@Nonnull final String sBundleName, @Nonnull final Locale aContentLocale); @Nullable static ResourceBundle getResourceBundle(@Nonnull final String sBundleName,
                                                  @Nonnull final Locale aContentLocale,
                                                  @Nonnull final ClassLoader aClassLoader); @Nullable static ResourceBundle getUtf8ResourceBundle(@Nonnull final String sBundleName, @Nonnull final Locale aContentLocale); @Nullable static ResourceBundle getUtf8ResourceBundle(@Nonnull final String sBundleName,
                                                      @Nonnull final Locale aContentLocale,
                                                      @Nonnull final ClassLoader aClassLoader); @Nullable static String getString(@Nullable final ResourceBundle aResourceBundle, @Nonnull @PropertyKey final String sKey); @Nullable static String getString(@Nonnull final String sBundleName,
                                  @Nonnull final Locale aContentLocale,
                                  @Nonnull @PropertyKey final String sKey); @Nullable static String getString(@Nonnull final String sBundleName,
                                  @Nonnull final Locale aContentLocale,
                                  @Nonnull @PropertyKey final String sKey,
                                  @Nonnull final ClassLoader aClassLoader); @Nullable static String getUtf8String(@Nonnull final String sBundleName,
                                      @Nonnull final Locale aContentLocale,
                                      @Nonnull @PropertyKey final String sKey); @Nullable static String getUtf8String(@Nonnull final String sBundleName,
                                      @Nonnull final Locale aContentLocale,
                                      @Nonnull @PropertyKey final String sKey,
                                      @Nonnull final ClassLoader aClassLoader); static void clearCache(); static void clearCache(@Nonnull final ClassLoader aClassLoader);  }### Answer:
@Test public void testGetString () { assertEquals ("äöü", ResourceBundleHelper.getString ("properties/test-iso8859", L_DE, "key1")); assertNull (ResourceBundleHelper.getString ("properties/test-iso8859-noway", L_DE, "key1")); assertEquals ("äöü", ResourceBundleHelper.getString ("properties/test-iso8859", L_FR, "key1")); assertNull (ResourceBundleHelper.getString ("properties/test-iso8859", L_DE, "key-noway")); assertEquals ("abc", ResourceBundleHelper.getString ("properties/test-iso8859", L_DE, "key2")); assertEquals ("colon", ResourceBundleHelper.getString ("properties/test-iso8859", L_DE, "key3")); assertEquals ("a:b", ResourceBundleHelper.getString ("properties/test-iso8859", L_DE, "key4")); assertEquals ("a=b", ResourceBundleHelper.getString ("properties/test-iso8859", L_DE, "key5")); assertEquals ("a#b", ResourceBundleHelper.getString ("properties/test-iso8859", L_DE, "key6")); assertEquals ("a:b", ResourceBundleHelper.getString ("properties/test-iso8859", L_DE, "key7")); assertEquals ("a=b", ResourceBundleHelper.getString ("properties/test-iso8859", L_DE, "key8")); assertEquals ("a#b", ResourceBundleHelper.getString ("properties/test-iso8859", L_DE, "key9")); }