--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/util/Hashtable/SelfRef.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2001-2005 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/**
+ * @test
+ * @bug 4421469 6282555
+ * @summary Hashtable's toString method should detect self-referential
+ *          hash tables rather than throwing a StackOverflowException.
+ * @author Josh Bloch, Martin Buchholz
+ */
+
+import java.util.*;
+import java.util.concurrent.*;
+
+public class SelfRef {
+    public static void main(String[] args) {
+        testMap(new Hashtable<Object,Object>());
+        testMap(new HashMap<Object,Object>());
+        testMap(new LinkedHashMap<Object,Object>());
+        testMap(new ConcurrentHashMap<Object,Object>());
+    }
+
+    private static void testMap(Map<Object,Object> m) {
+        if (! (m.toString().equals("{}")))
+            throw new Error();
+        m.put("Harvey", m);
+        if (! (m.toString().equals("{Harvey=(this Map)}")))
+            throw new Error();
+        m.clear();
+        m.put(m, "Harvey");
+        if (! (m.toString().equals("{(this Map)=Harvey}")))
+            throw new Error();
+        m.clear();
+        m.hashCode();
+    }
+}