--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/java/util/Comparators.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2012, 2013, Oracle and/or its affiliates. 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package java.util;
+
+import java.io.Serializable;
+import java.util.function.BinaryOperator;
+import java.util.function.Function;
+import java.util.function.ToDoubleFunction;
+import java.util.function.ToIntFunction;
+import java.util.function.ToLongFunction;
+
+/**
+ * Package private supporting class for {@link Comparator}.
+ */
+class Comparators {
+    private Comparators() {
+        throw new AssertionError("no instances");
+    }
+
+    /**
+     * Compares {@link Comparable} objects in natural order.
+     *
+     * @see Comparable
+     */
+    enum NaturalOrderComparator implements Comparator<Comparable<Object>> {
+        INSTANCE;
+
+        @Override
+        public int compare(Comparable<Object> c1, Comparable<Object> c2) {
+            return c1.compareTo(c2);
+        }
+
+        @Override
+        public Comparator<Comparable<Object>> reversed() {
+            return Comparator.reverseOrder();
+        }
+    }
+
+    /**
+     * Null-friendly comparators
+     */
+    static final class NullComparator<T> implements Comparator<T>, Serializable {
+        private static final long serialVersionUID = -7569533591570686392L;
+        private final boolean nullFirst;
+        // if null, non-null Ts are considered equal
+        private final Comparator<T> real;
+
+        @SuppressWarnings("unchecked")
+        NullComparator(boolean nullFirst, Comparator<? super T> real) {
+            this.nullFirst = nullFirst;
+            this.real = (Comparator<T>) real;
+        }
+
+        @Override
+        public int compare(T a, T b) {
+            if (a == null) {
+                return (b == null) ? 0 : (nullFirst ? -1 : 1);
+            } else if (b == null) {
+                return nullFirst ? 1: -1;
+            } else {
+                return (real == null) ? 0 : real.compare(a, b);
+            }
+        }
+
+        @Override
+        public Comparator<T> thenComparing(Comparator<? super T> other) {
+            Objects.requireNonNull(other);
+            return new NullComparator<>(nullFirst, real == null ? other : real.thenComparing(other));
+        }
+
+        @Override
+        public Comparator<T> reversed() {
+            return new NullComparator<>(!nullFirst, real == null ? null : real.reversed());
+        }
+    }
+}