# HG changeset patch
# User redestad
# Date 1511190101 -3600
#      Mon Nov 20 16:01:41 2017 +0100
# Node ID 15663ec3c162efac8c816af2a3af91eaabafe724
# Parent  4fab795915b645475a8ed94c46e2c9ae3f27409c
imported patch immu0

diff --git a/src/java.base/share/classes/java/util/ImmutableCollections.java b/src/java.base/share/classes/java/util/ImmutableCollections.java
--- a/src/java.base/share/classes/java/util/ImmutableCollections.java
+++ b/src/java.base/share/classes/java/util/ImmutableCollections.java
@@ -59,6 +59,8 @@
         SALT = (int)((nt >>> 32) ^ nt);
     }
 
+    private static final Object NULL = new Object();
+
     /** No instances. */
     private ImmutableCollections() { }
 
@@ -86,55 +88,25 @@
         @Override public void    sort(Comparator<? super E> c) { throw uoe(); }
     }
 
-    static final class List0<E> extends AbstractImmutableList<E> {
-        private static final List0<?> INSTANCE = new List0<>();
+    static final List<?> EMPTY_LIST = new ListN<>();
 
-        @SuppressWarnings("unchecked")
-        static <T> List0<T> instance() {
-            return (List0<T>) INSTANCE;
-        }
+    static final Set<?> EMPTY_SET = new SetN<>();
 
-        private List0() { }
+    static final Map<?,?> EMPTY_MAP = new MapN<>();
 
-        @Override
-        public int size() {
-            return 0;
-        }
+    @SuppressWarnings("unchecked")
+    static <T> List<T> emptyList() {
+        return (List<T>) EMPTY_LIST;
+    }
 
-        @Override
-        public E get(int index) {
-            Objects.checkIndex(index, 0); // always throws IndexOutOfBoundsException
-            return null;                  // but the compiler doesn't know this
-        }
+    @SuppressWarnings("unchecked")
+    static <T> Set<T> emptySet() {
+        return (Set<T>) EMPTY_SET;
+    }
 
-        @Override
-        public Iterator<E> iterator() {
-            return Collections.emptyIterator();
-        }
-
-        private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
-            throw new InvalidObjectException("not serial proxy");
-        }
-
-        private Object writeReplace() {
-            return new CollSer(CollSer.IMM_LIST);
-        }
-
-        @Override
-        public boolean contains(Object o) {
-            Objects.requireNonNull(o);
-            return false;
-        }
-
-        @Override
-        public boolean containsAll(Collection<?> o) {
-            return o.isEmpty(); // implicit nullcheck of o
-        }
-
-        @Override
-        public int hashCode() {
-            return 1;
-        }
+    @SuppressWarnings("unchecked")
+    static <K,V> Map<K,V> emptyMap() {
+        return (Map<K,V>) EMPTY_MAP;
     }
 
     static final class List1<E> extends AbstractImmutableList<E> {
@@ -175,52 +147,6 @@
         }
     }
 
-    static final class List2<E> extends AbstractImmutableList<E> {
-        @Stable
-        private final E e0;
-        @Stable
-        private final E e1;
-
-        List2(E e0, E e1) {
-            this.e0 = Objects.requireNonNull(e0);
-            this.e1 = Objects.requireNonNull(e1);
-        }
-
-        @Override
-        public int size() {
-            return 2;
-        }
-
-        @Override
-        public E get(int index) {
-            Objects.checkIndex(index, 2);
-            if (index == 0) {
-                return e0;
-            } else { // index == 1
-                return e1;
-            }
-        }
-
-        @Override
-        public boolean contains(Object o) {
-            return o.equals(e0) || o.equals(e1); // implicit nullcheck of o
-        }
-
-        @Override
-        public int hashCode() {
-            int hash = 31 + e0.hashCode();
-            return 31 * hash + e1.hashCode();
-        }
-
-        private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
-            throw new InvalidObjectException("not serial proxy");
-        }
-
-        private Object writeReplace() {
-            return new CollSer(CollSer.IMM_LIST, e0, e1);
-        }
-    }
-
     static final class ListN<E> extends AbstractImmutableList<E> {
         @Stable
         private final E[] elements;
@@ -287,51 +213,6 @@
         @Override public boolean retainAll(Collection<?> c) { throw uoe(); }
     }
 
-    static final class Set0<E> extends AbstractImmutableSet<E> {
-        private static final Set0<?> INSTANCE = new Set0<>();
-
-        @SuppressWarnings("unchecked")
-        static <T> Set0<T> instance() {
-            return (Set0<T>) INSTANCE;
-        }
-
-        private Set0() { }
-
-        @Override
-        public int size() {
-            return 0;
-        }
-
-        @Override
-        public boolean contains(Object o) {
-            Objects.requireNonNull(o);
-            return false;
-        }
-
-        @Override
-        public boolean containsAll(Collection<?> o) {
-            return o.isEmpty(); // implicit nullcheck of o
-        }
-
-        @Override
-        public Iterator<E> iterator() {
-            return Collections.emptyIterator();
-        }
-
-        private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
-            throw new InvalidObjectException("not serial proxy");
-        }
-
-        private Object writeReplace() {
-            return new CollSer(CollSer.IMM_SET);
-        }
-
-        @Override
-        public int hashCode() {
-            return 0;
-        }
-    }
-
     static final class Set1<E> extends AbstractImmutableSet<E> {
         @Stable
         private final E e0;
@@ -369,75 +250,6 @@
         }
     }
 
-    static final class Set2<E> extends AbstractImmutableSet<E> {
-        @Stable
-        final E e0;
-        @Stable
-        final E e1;
-
-        Set2(E e0, E e1) {
-            if (e0.equals(Objects.requireNonNull(e1))) { // implicit nullcheck of e0
-                throw new IllegalArgumentException("duplicate element: " + e0);
-            }
-
-            if (SALT >= 0) {
-                this.e0 = e0;
-                this.e1 = e1;
-            } else {
-                this.e0 = e1;
-                this.e1 = e0;
-            }
-        }
-
-        @Override
-        public int size() {
-            return 2;
-        }
-
-        @Override
-        public boolean contains(Object o) {
-            return o.equals(e0) || o.equals(e1); // implicit nullcheck of o
-        }
-
-        @Override
-        public int hashCode() {
-            return e0.hashCode() + e1.hashCode();
-        }
-
-        @Override
-        public Iterator<E> iterator() {
-            return new Iterator<E>() {
-                private int idx = 0;
-
-                @Override
-                public boolean hasNext() {
-                    return idx < 2;
-                }
-
-                @Override
-                public E next() {
-                    if (idx == 0) {
-                        idx = 1;
-                        return e0;
-                    } else if (idx == 1) {
-                        idx = 2;
-                        return e1;
-                    } else {
-                        throw new NoSuchElementException();
-                    }
-                }
-            };
-        }
-
-        private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
-            throw new InvalidObjectException("not serial proxy");
-        }
-
-        private Object writeReplace() {
-            return new CollSer(CollSer.IMM_SET, e0, e1);
-        }
-    }
-
     /**
      * An array-based Set implementation. The element array must be strictly
      * larger than the size (the number of contained elements) so that at
@@ -474,7 +286,8 @@
 
         @Override
         public boolean contains(Object o) {
-            return probe(o) >= 0; // implicit nullcheck of o
+            Objects.requireNonNull(0);
+            return size > 0 && probe(o) >= 0; // implicit nullcheck of o
         }
 
         @Override
@@ -565,47 +378,6 @@
         @Override public void replaceAll(BiFunction<? super K,? super V,? extends V> f) { throw uoe(); }
     }
 
-    static final class Map0<K,V> extends AbstractImmutableMap<K,V> {
-        private static final Map0<?,?> INSTANCE = new Map0<>();
-
-        @SuppressWarnings("unchecked")
-        static <K,V> Map0<K,V> instance() {
-            return (Map0<K,V>) INSTANCE;
-        }
-
-        private Map0() { }
-
-        @Override
-        public Set<Map.Entry<K,V>> entrySet() {
-            return Set.of();
-        }
-
-        @Override
-        public boolean containsKey(Object o) {
-            Objects.requireNonNull(o);
-            return false;
-        }
-
-        @Override
-        public boolean containsValue(Object o) {
-            Objects.requireNonNull(o);
-            return false;
-        }
-
-        private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
-            throw new InvalidObjectException("not serial proxy");
-        }
-
-        private Object writeReplace() {
-            return new CollSer(CollSer.IMM_MAP);
-        }
-
-        @Override
-        public int hashCode() {
-            return 0;
-        }
-    }
-
     static final class Map1<K,V> extends AbstractImmutableMap<K,V> {
         @Stable
         private final K k0;
@@ -658,7 +430,6 @@
     static final class MapN<K,V> extends AbstractImmutableMap<K,V> {
         @Stable
         final Object[] table; // pairs of key, value
-        @Stable
         final int size; // number of pairs
 
         MapN(Object... input) {
@@ -689,7 +460,8 @@
 
         @Override
         public boolean containsKey(Object o) {
-            return probe(o) >= 0; // implicit nullcheck of o
+            Objects.requireNonNull(0);
+            return size > 0 && probe(o) >= 0;
         }
 
         @Override
@@ -718,6 +490,9 @@
         @Override
         @SuppressWarnings("unchecked")
         public V get(Object o) {
+            if (size == 0) {
+                return null;
+            }
             int i = probe(o);
             if (i >= 0) {
                 return (V)table[i+1];
@@ -948,7 +723,7 @@
                     return Set.of(array);
                 case IMM_MAP:
                     if (array.length == 0) {
-                        return ImmutableCollections.Map0.instance();
+                        return ImmutableCollections.emptyMap();
                     } else if (array.length == 2) {
                         return new ImmutableCollections.Map1<>(array[0], array[1]);
                     } else {
diff --git a/src/java.base/share/classes/java/util/List.java b/src/java.base/share/classes/java/util/List.java
--- a/src/java.base/share/classes/java/util/List.java
+++ b/src/java.base/share/classes/java/util/List.java
@@ -787,7 +787,7 @@
      * @since 9
      */
     static <E> List<E> of() {
-        return ImmutableCollections.List0.instance();
+        return ImmutableCollections.emptyList();
     }
 
     /**
@@ -820,7 +820,7 @@
      * @since 9
      */
     static <E> List<E> of(E e1, E e2) {
-        return new ImmutableCollections.List2<>(e1, e2);
+        return new ImmutableCollections.ListN<>(e1, e2);
     }
 
     /**
@@ -1030,11 +1030,9 @@
     static <E> List<E> of(E... elements) {
         switch (elements.length) { // implicit null check of elements
             case 0:
-                return ImmutableCollections.List0.instance();
+                return ImmutableCollections.emptyList();
             case 1:
                 return new ImmutableCollections.List1<>(elements[0]);
-            case 2:
-                return new ImmutableCollections.List2<>(elements[0], elements[1]);
             default:
                 return new ImmutableCollections.ListN<>(elements);
         }
diff --git a/src/java.base/share/classes/java/util/Map.java b/src/java.base/share/classes/java/util/Map.java
--- a/src/java.base/share/classes/java/util/Map.java
+++ b/src/java.base/share/classes/java/util/Map.java
@@ -1286,7 +1286,7 @@
      * @since 9
      */
     static <K, V> Map<K, V> of() {
-        return ImmutableCollections.Map0.instance();
+        return ImmutableCollections.emptyMap();
     }
 
     /**
@@ -1603,7 +1603,7 @@
     @SuppressWarnings("varargs")
     static <K, V> Map<K, V> ofEntries(Entry<? extends K, ? extends V>... entries) {
         if (entries.length == 0) { // implicit null check of entries
-            return ImmutableCollections.Map0.instance();
+            return ImmutableCollections.emptyMap();
         } else if (entries.length == 1) {
             return new ImmutableCollections.Map1<>(entries[0].getKey(),
                                                    entries[0].getValue());
diff --git a/src/java.base/share/classes/java/util/Set.java b/src/java.base/share/classes/java/util/Set.java
--- a/src/java.base/share/classes/java/util/Set.java
+++ b/src/java.base/share/classes/java/util/Set.java
@@ -448,7 +448,7 @@
      * @since 9
      */
     static <E> Set<E> of() {
-        return ImmutableCollections.Set0.instance();
+        return ImmutableCollections.emptySet();
     }
 
     /**
@@ -480,7 +480,7 @@
      * @since 9
      */
     static <E> Set<E> of(E e1, E e2) {
-        return new ImmutableCollections.Set2<>(e1, e2);
+        return new ImmutableCollections.SetN<>(e1, e2);
     }
 
     /**
@@ -691,11 +691,9 @@
     static <E> Set<E> of(E... elements) {
         switch (elements.length) { // implicit null check of elements
             case 0:
-                return ImmutableCollections.Set0.instance();
+                return ImmutableCollections.emptySet();
             case 1:
                 return new ImmutableCollections.Set1<>(elements[0]);
-            case 2:
-                return new ImmutableCollections.Set2<>(elements[0], elements[1]);
             default:
                 return new ImmutableCollections.SetN<>(elements);
         }
# HG changeset patch
# User redestad
# Date 1511196859 -3600
#      Mon Nov 20 17:54:19 2017 +0100
# Node ID 5fd20486d4c1d62f09231cd4e3a3d0d625a5449b
# Parent  15663ec3c162efac8c816af2a3af91eaabafe724
imported patch listn

diff --git a/src/java.base/share/classes/java/util/AbstractList.java b/src/java.base/share/classes/java/util/AbstractList.java
--- a/src/java.base/share/classes/java/util/AbstractList.java
+++ b/src/java.base/share/classes/java/util/AbstractList.java
@@ -341,6 +341,7 @@
     }
 
     private class Itr implements Iterator<E> {
+
         /**
          * Index of element to be returned by subsequent call to next.
          */
diff --git a/src/java.base/share/classes/java/util/ImmutableCollections.java b/src/java.base/share/classes/java/util/ImmutableCollections.java
--- a/src/java.base/share/classes/java/util/ImmutableCollections.java
+++ b/src/java.base/share/classes/java/util/ImmutableCollections.java
@@ -74,20 +74,6 @@
 
     // ---------- List Implementations ----------
 
-    abstract static class AbstractImmutableList<E> extends AbstractList<E>
-                                                implements RandomAccess, Serializable {
-        @Override public boolean add(E e) { throw uoe(); }
-        @Override public boolean addAll(Collection<? extends E> c) { throw uoe(); }
-        @Override public boolean addAll(int index, Collection<? extends E> c) { throw uoe(); }
-        @Override public void    clear() { throw uoe(); }
-        @Override public boolean remove(Object o) { throw uoe(); }
-        @Override public boolean removeAll(Collection<?> c) { throw uoe(); }
-        @Override public boolean removeIf(Predicate<? super E> filter) { throw uoe(); }
-        @Override public void    replaceAll(UnaryOperator<E> operator) { throw uoe(); }
-        @Override public boolean retainAll(Collection<?> c) { throw uoe(); }
-        @Override public void    sort(Comparator<? super E> c) { throw uoe(); }
-    }
-
     static final List<?> EMPTY_LIST = new ListN<>();
 
     static final Set<?> EMPTY_SET = new SetN<>();
@@ -109,95 +95,394 @@
         return (Map<K,V>) EMPTY_MAP;
     }
 
-    static final class List1<E> extends AbstractImmutableList<E> {
-        @Stable
-        private final E e0;
+    static final class ListN<E> extends AbstractCollection<E>
+            implements List<E>, RandomAccess, Serializable {
 
-        List1(E e0) {
-            this.e0 = Objects.requireNonNull(e0);
+        // all mutating methods throw UnsupportedOperationException
+        @Override public boolean add(E e) { throw uoe(); }
+        @Override public void    add(int index, E element) { throw uoe(); }
+        @Override public boolean addAll(Collection<? extends E> c) { throw uoe(); }
+        @Override public boolean addAll(int index, Collection<? extends E> c) { throw uoe(); }
+        @Override public void    clear() { throw uoe(); }
+        @Override public boolean remove(Object o) { throw uoe(); }
+        @Override public E       remove(int index) { throw uoe(); }
+        @Override public boolean removeAll(Collection<?> c) { throw uoe(); }
+        @Override public boolean removeIf(Predicate<? super E> filter) { throw uoe(); }
+        @Override public void    replaceAll(UnaryOperator<E> operator) { throw uoe(); }
+        @Override public boolean retainAll(Collection<?> c) { throw uoe(); }
+        @Override public E       set(int index, E element) { throw uoe(); }
+        @Override public void    sort(Comparator<? super E> c) { throw uoe(); }
+
+        @Override
+        public int indexOf(Object o) {
+            Objects.requireNonNull(o);
+            ListIterator<E> it = listIterator();
+            while (it.hasNext()) {
+                if (o.equals(it.next())) {
+                    return it.previousIndex();
+                }
+            }
+            return -1;
         }
 
         @Override
-        public int size() {
-            return 1;
+        public int lastIndexOf(Object o) {
+            Objects.requireNonNull(o);
+            ListIterator<E> it = listIterator();
+            while (it.hasNext()) {
+                if (o.equals(it.next())) {
+                    return it.previousIndex();
+                }
+            }
+            return -1;
         }
 
         @Override
+        public boolean equals(Object o) {
+            if (o == this) {
+                return true;
+            }
+
+            if (!(o instanceof List)) {
+                return false;
+            }
+
+            if (!(o instanceof ListN)) {
+                ListN<?> other = (ListN<?>)o;
+                return this.e0.equals(other.e0) && this.e1.equals(e1);
+            }
+
+            ListIterator<E> e1 = listIterator();
+            ListIterator<?> e2 = ((List<?>) o).listIterator();
+            while (e1.hasNext() && e2.hasNext()) {
+                E o1 = e1.next();
+                Object o2 = e2.next();
+                if (!(o1==null ? o2==null : o1.equals(o2)))
+                    return false;
+            }
+            return !(e1.hasNext() || e2.hasNext());
+        }
+
+        @Override
+        public List<E> subList(int fromIndex, int toIndex) {
+            int size = size();
+            Objects.checkFromToIndex(fromIndex, toIndex, size);
+            if (size == 0 || fromIndex == toIndex) {
+                return emptyList();
+            } else if (size == 1) {
+                // checks above deal with corner cases subList(0,0) and subList(1,1)
+                // that would return the empty list
+                assert(fromIndex == 0 && toIndex == 1);
+                return this;
+            } else {
+                return new SubList<E>(this, fromIndex, toIndex);
+            }
+        }
+
+        private static class SubList<E> extends AbstractList<E> implements RandomAccess {
+            private final List<E> root;
+            private final int offset;
+            int size;
+
+            // all mutating methods throw UnsupportedOperationException
+            @Override public boolean add(E e) { throw uoe(); }
+            @Override public void    add(int index, E element) { throw uoe(); }
+            @Override public boolean addAll(Collection<? extends E> c) { throw uoe(); }
+            @Override public boolean addAll(int index, Collection<? extends E> c) { throw uoe(); }
+            @Override public void    clear() { throw uoe(); }
+            @Override public boolean remove(Object o) { throw uoe(); }
+            @Override public E       remove(int index) { throw uoe(); }
+            @Override public boolean removeAll(Collection<?> c) { throw uoe(); }
+            @Override public boolean removeIf(Predicate<? super E> filter) { throw uoe(); }
+            @Override public void    replaceAll(UnaryOperator<E> operator) { throw uoe(); }
+            @Override public boolean retainAll(Collection<?> c) { throw uoe(); }
+            @Override public E       set(int index, E element) { throw uoe(); }
+            @Override public void    sort(Comparator<? super E> c) { throw uoe(); }
+
+            /**
+             * Constructs a sublist of an arbitrary AbstractList, which is
+             * not a SubList itself.
+             */
+            public SubList(List<E> root, int fromIndex, int toIndex) {
+                this.root = root;
+                this.offset = fromIndex;
+                this.size = toIndex - fromIndex;
+            }
+
+            /**
+             * Constructs a sublist of another SubList.
+             */
+            protected SubList(SubList<E> parent, int fromIndex, int toIndex) {
+                this.root = parent.root;
+                this.offset = parent.offset + fromIndex;
+                this.size = toIndex - fromIndex;
+            }
+
+            public E get(int index) {
+                Objects.checkIndex(index, size);
+                return root.get(offset + index);
+            }
+
+            public int size() {
+                return size;
+            }
+
+            protected void removeRange(int fromIndex, int toIndex) {
+                throw uoe();
+            }
+
+            public Iterator<E> iterator() {
+                return listIterator();
+            }
+
+            public ListIterator<E> listIterator(int index) {
+                rangeCheck(index);
+
+                return new ListIterator<E>() {
+                    private final ListIterator<E> i =
+                            root.listIterator(offset + index);
+
+                    public boolean hasNext() {
+                        return nextIndex() < size;
+                    }
+
+                    public E next() {
+                        if (hasNext())
+                            return i.next();
+                        else
+                            throw new NoSuchElementException();
+                    }
+
+                    public boolean hasPrevious() {
+                        return previousIndex() >= 0;
+                    }
+
+                    public E previous() {
+                        if (hasPrevious())
+                            return i.previous();
+                        else
+                            throw new NoSuchElementException();
+                    }
+
+                    public int nextIndex() {
+                        return i.nextIndex() - offset;
+                    }
+
+                    public int previousIndex() {
+                        return i.previousIndex() - offset;
+                    }
+
+                    public void remove() { throw uoe(); }
+                    public void set(E e) { throw uoe(); }
+                    public void add(E e) { throw uoe(); }
+                };
+            }
+
+            public List<E> subList(int fromIndex, int toIndex) {
+                subListRangeCheck(fromIndex, toIndex, size);
+                return new SubList<>(this, fromIndex, toIndex);
+            }
+
+            private void rangeCheck(int index) {
+                if (index < 0 || index > size)
+                    throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
+            }
+
+            private String outOfBoundsMsg(int index) {
+                return "Index: "+index+", Size: "+size;
+            }
+        }
+
+        @Stable
+        private final Object e0;
+
+        @Stable
+        private final Object e1;
+
+        private final int size;
+
+        @SafeVarargs
+        ListN(E... input) {
+            if (input.length == 1) {
+                e0 = Objects.requireNonNull(input[0]);
+                e1 = NULL;
+                size = 1;
+            } else if (input.length == 2) {
+                e0 = Objects.requireNonNull(input[0]);
+                e1 = Objects.requireNonNull(input[1]);
+                size = 2;
+            } else {
+                e0 = NULL;
+                // copy and check manually to avoid TOCTOU
+                @SuppressWarnings("unchecked")
+                E[] tmp = (E[])new Object[input.length]; // implicit nullcheck of input
+                for (int i = 0; i < input.length; i++) {
+                    tmp[i] = Objects.requireNonNull(input[i]);
+                }
+                this.e1 = tmp;
+                size = input.length;
+            }
+        }
+
+        @Override
+        public boolean isEmpty() {
+            return size() == 0;
+        }
+
+        @Override
+        @SuppressWarnings("unchecked")
+        public int size() {
+            return size;
+        }
+
+        @Override
+        @SuppressWarnings("unchecked")
         public E get(int index) {
-            Objects.checkIndex(index, 1);
-            return e0;
+            int size = size();
+            Objects.checkIndex(index, size); // IOOBE if size == 0, or size == 1 and index == 1
+            if (size <= 2) {
+                if (index == 0) {
+                    return (E)e0;
+                } else {
+                    return (E)e1;
+                }
+            } else {
+                return ((E[]) e1)[index];
+            }
+        }
+
+        @Override
+        @SuppressWarnings("unchecked")
+        public boolean contains(Object o) {
+            int size = size();
+            Objects.requireNonNull(o);
+            if (size == 1) {
+                return o.equals(e0);
+            } else if (size == 2) {
+                return o.equals(e0) || o.equals(e1);
+            } else {
+                for (E e : (E[])e1) {
+                    if (o.equals(e)) { // implicit nullcheck of o
+                        return true;
+                    }
+                }
+                return false;
+            }
+        }
+
+        @Override
+        @SuppressWarnings("unchecked")
+        public int hashCode() {
+            int size = size();
+            if (size == 1) {
+                return 31 + e0.hashCode();
+            } else if (size == 2) {
+                return (31 + e0.hashCode()) * 31 + e1.hashCode();
+            }
+
+            int hash = 1;
+            for (E e : (E[])e1) {
+                hash = 31 * hash + e.hashCode();
+            }
+            return hash;
+        }
+
+        @Override
+        public Iterator<E> iterator() {
+            return new Itr();
+        }
+
+        @Override
+        public ListIterator<E> listIterator() {
+            return listIterator(0);
+        }
+
+        @Override
+        public ListIterator<E> listIterator(final int index) {
+            Objects.checkIndex(index, size());
+            return new ListItr(index);
+        }
+
+        private class Itr implements Iterator<E> {
+            Itr() {
+                size = size();
+            }
+
+            int cursor = 0;
+
+            private final int size;
+
+            public boolean hasNext() {
+                return cursor != size;
+            }
+
+            public E next() {
+                try {
+                    int i = cursor;
+                    E next = get(i);
+                    cursor = i + 1;
+                    return next;
+                } catch (IndexOutOfBoundsException e) {
+                    throw new NoSuchElementException();
+                }
+            }
+
+            public void remove() {
+                throw uoe();
+            }
+        }
+
+        private class ListItr extends Itr implements ListIterator<E> {
+            ListItr(int index) {
+                cursor = index;
+            }
+
+            public boolean hasPrevious() {
+                return cursor != 0;
+            }
+
+            public E previous() {
+                try {
+                    int i = cursor - 1;
+                    E previous = get(i);
+                    cursor = i;
+                    return previous;
+                } catch (IndexOutOfBoundsException e) {
+                    throw new NoSuchElementException();
+                }
+            }
+
+            public int nextIndex() {
+                return cursor;
+            }
+
+            public int previousIndex() {
+                return cursor - 1;
+            }
+
+            public void set(E e) {
+                throw uoe();
+            }
+
+            public void add(E e) {
+                throw uoe();
+            }
         }
 
         private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
             throw new InvalidObjectException("not serial proxy");
         }
 
+        @SuppressWarnings("unchecked")
         private Object writeReplace() {
-            return new CollSer(CollSer.IMM_LIST, e0);
-        }
-
-        @Override
-        public boolean contains(Object o) {
-            return o.equals(e0); // implicit nullcheck of o
-        }
-
-        @Override
-        public int hashCode() {
-            return 31 + e0.hashCode();
-        }
-    }
-
-    static final class ListN<E> extends AbstractImmutableList<E> {
-        @Stable
-        private final E[] elements;
-
-        @SafeVarargs
-        ListN(E... input) {
-            // copy and check manually to avoid TOCTOU
-            @SuppressWarnings("unchecked")
-            E[] tmp = (E[])new Object[input.length]; // implicit nullcheck of input
-            for (int i = 0; i < input.length; i++) {
-                tmp[i] = Objects.requireNonNull(input[i]);
+            int size = size();
+            if (size == 1) {
+                return new CollSer(CollSer.IMM_LIST, (E)e0);
+            } else if (size == 2) {
+                return new CollSer(CollSer.IMM_LIST, (E)e0, (E)e1);
+            } else {
+                return new CollSer(CollSer.IMM_LIST, (E[])e1);
             }
-            this.elements = tmp;
-        }
-
-        @Override
-        public int size() {
-            return elements.length;
-        }
-
-        @Override
-        public E get(int index) {
-            Objects.checkIndex(index, elements.length);
-            return elements[index];
-        }
-
-        @Override
-        public boolean contains(Object o) {
-            for (E e : elements) {
-                if (o.equals(e)) { // implicit nullcheck of o
-                    return true;
-                }
-            }
-            return false;
-        }
-
-        @Override
-        public int hashCode() {
-            int hash = 1;
-            for (E e : elements) {
-                hash = 31 * hash + e.hashCode();
-            }
-            return hash;
-        }
-
-        private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
-            throw new InvalidObjectException("not serial proxy");
-        }
-
-        private Object writeReplace() {
-            return new CollSer(CollSer.IMM_LIST, elements);
         }
     }
 
diff --git a/src/java.base/share/classes/java/util/List.java b/src/java.base/share/classes/java/util/List.java
--- a/src/java.base/share/classes/java/util/List.java
+++ b/src/java.base/share/classes/java/util/List.java
@@ -803,7 +803,7 @@
      * @since 9
      */
     static <E> List<E> of(E e1) {
-        return new ImmutableCollections.List1<>(e1);
+        return new ImmutableCollections.ListN<>(e1);
     }
 
     /**
@@ -1031,8 +1031,6 @@
         switch (elements.length) { // implicit null check of elements
             case 0:
                 return ImmutableCollections.emptyList();
-            case 1:
-                return new ImmutableCollections.List1<>(elements[0]);
             default:
                 return new ImmutableCollections.ListN<>(elements);
         }