* gnu/java/util/DoubleEnumeration.java: new class, adapted from

	java/util/DoubleEnumeration. Clears references earlier, handles null
	and/or empty enumerations better.
	* gnu/java/util/EmptyEnumeration.java: new class.

1 files changed, 77 insertions, 0 deletions

diff --git a/gnu/java/util/EmptyEnumeration.java b/gnu/java/util/EmptyEnumeration.java
new file mode 100644
index 000000000..5ee11d7d4
--- /dev/null
+++ b/gnu/java/util/EmptyEnumeration.java
@@ -0,0 +1,77 @@
+/* gnu.java.util.EmptyEnumeration
+   Copyright (C) 2001 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+ 
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+02111-1307 USA.
+
+As a special exception, if you link this library with other files to
+produce an executable, this library does not by itself cause the
+resulting executable to be covered by the GNU General Public License.
+This exception does not however invalidate any other reasons why the
+executable file might be covered by the GNU General Public License. */
+
+package gnu.java.util;
+
+import java.util.Enumeration;
+import java.util.NoSuchElementException;
+
+/**
+ * This is a helper class that produces an empty Enumerations.
+ * There is only one instance of this class that can be used whenever one
+ * needs a non-null but empty enumeration. Using this class prevents multiple
+ * small objects and inner classes. <code>getInstance()</code> returns
+ * the only instance of this class. It can be shared by multiple objects and
+ * threads
+ * <p>
+ * <code>hasMoreElements()</code> always returns <code>false</code>.
+ * <code>nextElement()</code> always throws <code>NoSuchElementException</code>.
+ * 
+ * @author Mark Wielaard (mark@klomp.org)
+ */
+public final class EmptyEnumeration implements Enumeration {
+
+    /** The only instance of this class */
+    private static final EmptyEnumeration instance = new EmptyEnumeration();
+
+    /**
+     * Private constructor that creates a new empty Enumeration.
+     */
+    private EmptyEnumeration() {
+    }
+
+    /**
+     * Returns the only instance of this class.
+     * It can be shared by multiple objects and threads.
+     */
+    public static EmptyEnumeration getInstance() {
+        return instance;
+    }
+
+    /**
+     * Always returns <code>false</code>.
+     */
+    public boolean hasMoreElements() {
+        return false;
+    }
+
+    /**
+     * Always throws <code>NoSuchElementException</code>.
+     */
+    public Object nextElement() throws NoSuchElementException {
+        throw new NoSuchElementException();
+    }
+}