src/java.base/share/classes/java/util/AbstractSet.java

rev 54827 : 6394757: AbstractSet.removeAll semantics are surprisingly dependent on relative sizes
Reviewed-by: XXX

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2019, 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

@@ -63,24 +63,31 @@
     protected AbstractSet() {
     }
 
     // Comparison and hashing
 
+    // FIXME: the first paragraph below is copied from Set.equals, because
+    // {@inheritDoc} inherits text from superclasses, not interfaces (see JDK-6376959).
     /**
      * Compares the specified object with this set for equality.  Returns
-     * {@code true} if the given object is also a set, the two sets have
-     * the same size, and every member of the given set is contained in
-     * this set.  This ensures that the {@code equals} method works
-     * properly across different implementations of the {@code Set}
-     * interface.<p>
+     * {@code true} if the specified object is also a set, the two sets
+     * have the same size, and every member of the specified set is
+     * contained in this set. This operation uses the membership semantics
+     * of this set. This definition ensures that the {@code equals} method
+     * works properly across different implementations of the
+     * {@code Set} interface.
      *
+     * @implSpec
      * This implementation first checks if the specified object is this
      * set; if so it returns {@code true}.  Then, it checks if the
      * specified object is a set whose size is identical to the size of
-     * this set; if not, it returns false.  If so, it returns
+     * this set; if not, it returns {@code false}.  If so, it returns
      * {@code containsAll((Collection) o)}.
      *
+     * @implNote
+     * {@inheritDoc}
+     *
      * @param o object to be compared for equality with this set
      * @return {@code true} if the specified object is equal to this set
      */
     public boolean equals(Object o) {
         if (o == this)

@@ -123,62 +130,6 @@
             if (obj != null)
                 h += obj.hashCode();
         }
         return h;
     }
-
-    /**
-     * Removes from this set all of its elements that are contained in the
-     * specified collection (optional operation).  If the specified
-     * collection is also a set, this operation effectively modifies this
-     * set so that its value is the <i>asymmetric set difference</i> of
-     * the two sets.
-     *
-     * <p>This implementation determines which is the smaller of this set
-     * and the specified collection, by invoking the {@code size}
-     * method on each.  If this set has fewer elements, then the
-     * implementation iterates over this set, checking each element
-     * returned by the iterator in turn to see if it is contained in
-     * the specified collection.  If it is so contained, it is removed
-     * from this set with the iterator's {@code remove} method.  If
-     * the specified collection has fewer elements, then the
-     * implementation iterates over the specified collection, removing
-     * from this set each element returned by the iterator, using this
-     * set's {@code remove} method.
-     *
-     * <p>Note that this implementation will throw an
-     * {@code UnsupportedOperationException} if the iterator returned by the
-     * {@code iterator} method does not implement the {@code remove} method.
-     *
-     * @param  c collection containing elements to be removed from this set
-     * @return {@code true} if this set changed as a result of the call
-     * @throws UnsupportedOperationException if the {@code removeAll} operation
-     *         is not supported by this set
-     * @throws ClassCastException if the class of an element of this set
-     *         is incompatible with the specified collection
-     * (<a href="Collection.html#optional-restrictions">optional</a>)
-     * @throws NullPointerException if this set contains a null element and the
-     *         specified collection does not permit null elements
-     * (<a href="Collection.html#optional-restrictions">optional</a>),
-     *         or if the specified collection is null
-     * @see #remove(Object)
-     * @see #contains(Object)
-     */
-    public boolean removeAll(Collection<?> c) {
-        Objects.requireNonNull(c);
-        boolean modified = false;
-
-        if (size() > c.size()) {
-            for (Object e : c)
-                modified |= remove(e);
-        } else {
-            for (Iterator<?> i = iterator(); i.hasNext(); ) {
-                if (c.contains(i.next())) {
-                    i.remove();
-                    modified = true;
-                }
-            }
-        }
-        return modified;
-    }
-
 }