8187443: Forest Consolidation: Move files to unified layout

Reviewed-by: darcy, ihse

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

@@ -0,0 +1,130 @@
+/*
+ * Copyright (c) 2015, 2017, 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 jdk.internal.vm.annotation.Stable;
+
+/**
+ * An immutable container for a key and a value, suitable for use
+ * in creating and populating {@code Map} instances.
+ *
+ * <p>This is a <a href="../lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code KeyValueHolder} may have unpredictable results and should be avoided.
+ *
+ * @apiNote
+ * This class is not public. Instances can be created using the
+ * {@link Map#entry Map.entry(k, v)} factory method, which is public.
+ *
+ * <p>This class differs from AbstractMap.SimpleImmutableEntry in the following ways:
+ * it is not serializable, it is final, and its key and value must be non-null.
+ *
+ * @param <K> the key type
+ * @param <V> the value type
+ *
+ * @see Map#ofEntries Map.ofEntries()
+ * @since 9
+ */
+final class KeyValueHolder<K,V> implements Map.Entry<K,V> {
+    @Stable
+    final K key;
+    @Stable
+    final V value;
+
+    KeyValueHolder(K k, V v) {
+        key = Objects.requireNonNull(k);
+        value = Objects.requireNonNull(v);
+    }
+
+    /**
+     * Gets the key from this holder.
+     *
+     * @return the key
+     */
+    @Override
+    public K getKey() {
+        return key;
+    }
+
+    /**
+     * Gets the value from this holder.
+     *
+     * @return the value
+     */
+    @Override
+    public V getValue() {
+        return value;
+    }
+
+    /**
+     * Throws {@link UnsupportedOperationException}.
+     *
+     * @param value ignored
+     * @return never returns normally
+     */
+    @Override
+    public V setValue(V value) {
+        throw new UnsupportedOperationException("not supported");
+    }
+
+    /**
+     * Compares the specified object with this entry for equality.
+     * Returns {@code true} if the given object is also a map entry and
+     * the two entries' keys and values are equal. Note that key and
+     * value are non-null, so equals() can be called safely on them.
+     */
+    @Override
+    public boolean equals(Object o) {
+        if (!(o instanceof Map.Entry))
+            return false;
+        Map.Entry<?,?> e = (Map.Entry<?,?>)o;
+        return key.equals(e.getKey()) && value.equals(e.getValue());
+    }
+
+    /**
+     * Returns the hash code value for this map entry. The hash code
+     * is {@code key.hashCode() ^ value.hashCode()}. Note that key and
+     * value are non-null, so hashCode() can be called safely on them.
+     */
+    @Override
+    public int hashCode() {
+        return key.hashCode() ^ value.hashCode();
+    }
+
+    /**
+     * Returns a String representation of this map entry.  This
+     * implementation returns the string representation of this
+     * entry's key followed by the equals character ("{@code =}")
+     * followed by the string representation of this entry's value.
+     *
+     * @return a String representation of this map entry
+     */
+    @Override
+    public String toString() {
+        return key + "=" + value;
+    }
+}