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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* published by the Free Software Foundation. Oracle designates this
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* by Oracle in the LICENSE file that accompanied this code.
*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
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*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package java.util;
/**
* A Red-Black tree based {@link NavigableMap} implementation.
* The map is sorted according to the {@linkplain Comparable natural
* ordering} of its keys, or by a {@link Comparator} provided at map
* creation time, depending on which constructor is used.
*
* This implementation provides guaranteed log(n) time cost for the
* {@code containsKey}, {@code get}, {@code put} and {@code remove}
* operations. Algorithms are adaptations of those in Cormen, Leiserson, and
* Rivest's Introduction to Algorithms.
*
*
Note that the ordering maintained by a tree map, like any sorted map, and
* whether or not an explicit comparator is provided, must be consistent
* with {@code equals} if this sorted map is to correctly implement the
* {@code Map} interface. (See {@code Comparable} or {@code Comparator} for a
* precise definition of consistent with equals.) This is so because
* the {@code Map} interface is defined in terms of the {@code equals}
* operation, but a sorted map performs all key comparisons using its {@code
* compareTo} (or {@code compare}) method, so two keys that are deemed equal by
* this method are, from the standpoint of the sorted map, equal. The behavior
* of a sorted map is well-defined even if its ordering is
* inconsistent with {@code equals}; it just fails to obey the general contract
* of the {@code Map} interface.
*
*
Note that this implementation is not synchronized.
* If multiple threads access a map concurrently, and at least one of the
* threads modifies the map structurally, it must be synchronized
* externally. (A structural modification is any operation that adds or
* deletes one or more mappings; merely changing the value associated
* with an existing key is not a structural modification.) This is
* typically accomplished by synchronizing on some object that naturally
* encapsulates the map.
* If no such object exists, the map should be "wrapped" using the
* {@link Collections#synchronizedSortedMap Collections.synchronizedSortedMap}
* method. This is best done at creation time, to prevent accidental
* unsynchronized access to the map:
* SortedMap m = Collections.synchronizedSortedMap(new TreeMap(...));
*
* The iterators returned by the {@code iterator} method of the collections
* returned by all of this class's "collection view methods" are
* fail-fast: if the map is structurally modified at any time after
* the iterator is created, in any way except through the iterator's own
* {@code remove} method, the iterator will throw a {@link
* ConcurrentModificationException}. Thus, in the face of concurrent
* modification, the iterator fails quickly and cleanly, rather than risking
* arbitrary, non-deterministic behavior at an undetermined time in the future.
*
*
Note that the fail-fast behavior of an iterator cannot be guaranteed
* as it is, generally speaking, impossible to make any hard guarantees in the
* presence of unsynchronized concurrent modification. Fail-fast iterators
* throw {@code ConcurrentModificationException} on a best-effort basis.
* Therefore, it would be wrong to write a program that depended on this
* exception for its correctness: the fail-fast behavior of iterators
* should be used only to detect bugs.
*
*
All {@code Map.Entry} pairs returned by methods in this class
* and its views represent snapshots of mappings at the time they were
* produced. They do not support the {@code Entry.setValue}
* method. (Note however that it is possible to change mappings in the
* associated map using {@code put}.)
*
*
This class is a member of the
*
* Java Collections Framework.
*
* @param the type of keys maintained by this map
* @param the type of mapped values
*
* @author Josh Bloch and Doug Lea
* @see Map
* @see HashMap
* @see Hashtable
* @see Comparable
* @see Comparator
* @see Collection
* @since 1.2
*/
public class TreeMap
extends AbstractMap
implements NavigableMap, Cloneable, java.io.Serializable
{
/**
* The comparator used to maintain order in this tree map, or
* null if it uses the natural ordering of its keys.
*
* @serial
*/
private final Comparator comparator;
private transient Entry root = null;
/**
* The number of entries in the tree
*/
private transient int size = 0;
/**
* The number of structural modifications to the tree.
*/
private transient int modCount = 0;
/**
* Constructs a new, empty tree map, using the natural ordering of its
* keys. All keys inserted into the map must implement the {@link
* Comparable} interface. Furthermore, all such keys must be
* mutually comparable: {@code k1.compareTo(k2)} must not throw
* a {@code ClassCastException} for any keys {@code k1} and
* {@code k2} in the map. If the user attempts to put a key into the
* map that violates this constraint (for example, the user attempts to
* put a string key into a map whose keys are integers), the
* {@code put(Object key, Object value)} call will throw a
* {@code ClassCastException}.
*/
public TreeMap() {
comparator = null;
}
/**
* Constructs a new, empty tree map, ordered according to the given
* comparator. All keys inserted into the map must be mutually
* comparable by the given comparator: {@code comparator.compare(k1,
* k2)} must not throw a {@code ClassCastException} for any keys
* {@code k1} and {@code k2} in the map. If the user attempts to put
* a key into the map that violates this constraint, the {@code put(Object
* key, Object value)} call will throw a
* {@code ClassCastException}.
*
* @param comparator the comparator that will be used to order this map.
* If {@code null}, the {@linkplain Comparable natural
* ordering} of the keys will be used.
*/
public TreeMap(Comparator comparator) {
this.comparator = comparator;
}
/**
* Constructs a new tree map containing the same mappings as the given
* map, ordered according to the natural ordering of its keys.
* All keys inserted into the new map must implement the {@link
* Comparable} interface. Furthermore, all such keys must be
* mutually comparable: {@code k1.compareTo(k2)} must not throw
* a {@code ClassCastException} for any keys {@code k1} and
* {@code k2} in the map. This method runs in n*log(n) time.
*
* @param m the map whose mappings are to be placed in this map
* @throws ClassCastException if the keys in m are not {@link Comparable},
* or are not mutually comparable
* @throws NullPointerException if the specified map is null
*/
public TreeMap(Map m) {
comparator = null;
putAll(m);
}
/**
* Constructs a new tree map containing the same mappings and
* using the same ordering as the specified sorted map. This
* method runs in linear time.
*
* @param m the sorted map whose mappings are to be placed in this map,
* and whose comparator is to be used to sort this map
* @throws NullPointerException if the specified map is null
*/
public TreeMap(SortedMap m) {
comparator = m.comparator();
try {
buildFromSorted(m.size(), m.entrySet().iterator(), null, null);
} catch (java.io.IOException cannotHappen) {
} catch (ClassNotFoundException cannotHappen) {
}
}
// Query Operations
/**
* Returns the number of key-value mappings in this map.
*
* @return the number of key-value mappings in this map
*/
public int size() {
return size;
}
/**
* Returns {@code true} if this map contains a mapping for the specified
* key.
*
* @param key key whose presence in this map is to be tested
* @return {@code true} if this map contains a mapping for the
* specified key
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
*/
public boolean containsKey(Object key) {
return getEntry(key) != null;
}
/**
* Returns {@code true} if this map maps one or more keys to the
* specified value. More formally, returns {@code true} if and only if
* this map contains at least one mapping to a value {@code v} such
* that {@code (value==null ? v==null : value.equals(v))}. This
* operation will probably require time linear in the map size for
* most implementations.
*
* @param value value whose presence in this map is to be tested
* @return {@code true} if a mapping to {@code value} exists;
* {@code false} otherwise
* @since 1.2
*/
public boolean containsValue(Object value) {
for (Entry e = getFirstEntry(); e != null; e = successor(e))
if (valEquals(value, e.value))
return true;
return false;
}
/**
* Returns the value to which the specified key is mapped,
* or {@code null} if this map contains no mapping for the key.
*
* More formally, if this map contains a mapping from a key
* {@code k} to a value {@code v} such that {@code key} compares
* equal to {@code k} according to the map's ordering, then this
* method returns {@code v}; otherwise it returns {@code null}.
* (There can be at most one such mapping.)
*
*
A return value of {@code null} does not necessarily
* indicate that the map contains no mapping for the key; it's also
* possible that the map explicitly maps the key to {@code null}.
* The {@link #containsKey containsKey} operation may be used to
* distinguish these two cases.
*
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
*/
public V get(Object key) {
Entry p = getEntry(key);
return (p==null ? null : p.value);
}
public Comparator comparator() {
return comparator;
}
/**
* @throws NoSuchElementException {@inheritDoc}
*/
public K firstKey() {
return key(getFirstEntry());
}
/**
* @throws NoSuchElementException {@inheritDoc}
*/
public K lastKey() {
return key(getLastEntry());
}
/**
* Copies all of the mappings from the specified map to this map.
* These mappings replace any mappings that this map had for any
* of the keys currently in the specified map.
*
* @param map mappings to be stored in this map
* @throws ClassCastException if the class of a key or value in
* the specified map prevents it from being stored in this map
* @throws NullPointerException if the specified map is null or
* the specified map contains a null key and this map does not
* permit null keys
*/
public void putAll(Map map) {
int mapSize = map.size();
if (size==0 && mapSize!=0 && map instanceof SortedMap) {
Comparator c = ((SortedMap)map).comparator();
if (c == comparator || (c != null && c.equals(comparator))) {
++modCount;
try {
buildFromSorted(mapSize, map.entrySet().iterator(),
null, null);
} catch (java.io.IOException cannotHappen) {
} catch (ClassNotFoundException cannotHappen) {
}
return;
}
}
super.putAll(map);
}
/**
* Returns this map's entry for the given key, or {@code null} if the map
* does not contain an entry for the key.
*
* @return this map's entry for the given key, or {@code null} if the map
* does not contain an entry for the key
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
*/
final Entry getEntry(Object key) {
// Offload comparator-based version for sake of performance
if (comparator != null)
return getEntryUsingComparator(key);
if (key == null)
throw new NullPointerException();
Comparable k = (Comparable) key;
Entry p = root;
while (p != null) {
int cmp = k.compareTo(p.key);
if (cmp < 0)
p = p.left;
else if (cmp > 0)
p = p.right;
else
return p;
}
return null;
}
/**
* Version of getEntry using comparator. Split off from getEntry
* for performance. (This is not worth doing for most methods,
* that are less dependent on comparator performance, but is
* worthwhile here.)
*/
final Entry getEntryUsingComparator(Object key) {
K k = (K) key;
Comparator cpr = comparator;
if (cpr != null) {
Entry p = root;
while (p != null) {
int cmp = cpr.compare(k, p.key);
if (cmp < 0)
p = p.left;
else if (cmp > 0)
p = p.right;
else
return p;
}
}
return null;
}
/**
* Gets the entry corresponding to the specified key; if no such entry
* exists, returns the entry for the least key greater than the specified
* key; if no such entry exists (i.e., the greatest key in the Tree is less
* than the specified key), returns {@code null}.
*/
final Entry getCeilingEntry(K key) {
Entry p = root;
while (p != null) {
int cmp = compare(key, p.key);
if (cmp < 0) {
if (p.left != null)
p = p.left;
else
return p;
} else if (cmp > 0) {
if (p.right != null) {
p = p.right;
} else {
Entry parent = p.parent;
Entry ch = p;
while (parent != null && ch == parent.right) {
ch = parent;
parent = parent.parent;
}
return parent;
}
} else
return p;
}
return null;
}
/**
* Gets the entry corresponding to the specified key; if no such entry
* exists, returns the entry for the greatest key less than the specified
* key; if no such entry exists, returns {@code null}.
*/
final Entry getFloorEntry(K key) {
Entry p = root;
while (p != null) {
int cmp = compare(key, p.key);
if (cmp > 0) {
if (p.right != null)
p = p.right;
else
return p;
} else if (cmp < 0) {
if (p.left != null) {
p = p.left;
} else {
Entry parent = p.parent;
Entry ch = p;
while (parent != null && ch == parent.left) {
ch = parent;
parent = parent.parent;
}
return parent;
}
} else
return p;
}
return null;
}
/**
* Gets the entry for the least key greater than the specified
* key; if no such entry exists, returns the entry for the least
* key greater than the specified key; if no such entry exists
* returns {@code null}.
*/
final Entry getHigherEntry(K key) {
Entry p = root;
while (p != null) {
int cmp = compare(key, p.key);
if (cmp < 0) {
if (p.left != null)
p = p.left;
else
return p;
} else {
if (p.right != null) {
p = p.right;
} else {
Entry parent = p.parent;
Entry ch = p;
while (parent != null && ch == parent.right) {
ch = parent;
parent = parent.parent;
}
return parent;
}
}
}
return null;
}
/**
* Returns the entry for the greatest key less than the specified key; if
* no such entry exists (i.e., the least key in the Tree is greater than
* the specified key), returns {@code null}.
*/
final Entry getLowerEntry(K key) {
Entry p = root;
while (p != null) {
int cmp = compare(key, p.key);
if (cmp > 0) {
if (p.right != null)
p = p.right;
else
return p;
} else {
if (p.left != null) {
p = p.left;
} else {
Entry parent = p.parent;
Entry ch = p;
while (parent != null && ch == parent.left) {
ch = parent;
parent = parent.parent;
}
return parent;
}
}
}
return null;
}
/**
* Associates the specified value with the specified key in this map.
* If the map previously contained a mapping for the key, the old
* value is replaced.
*
* @param key key with which the specified value is to be associated
* @param value value to be associated with the specified key
*
* @return the previous value associated with {@code key}, or
* {@code null} if there was no mapping for {@code key}.
* (A {@code null} return can also indicate that the map
* previously associated {@code null} with {@code key}.)
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
*/
public V put(K key, V value) {
Entry t = root;
if (t == null) {
compare(key, key); // type (and possibly null) check
root = new Entry<>(key, value, null);
size = 1;
modCount++;
return null;
}
int cmp;
Entry parent;
// split comparator and comparable paths
Comparator cpr = comparator;
if (cpr != null) {
do {
parent = t;
cmp = cpr.compare(key, t.key);
if (cmp < 0)
t = t.left;
else if (cmp > 0)
t = t.right;
else
return t.setValue(value);
} while (t != null);
}
else {
if (key == null)
throw new NullPointerException();
Comparable k = (Comparable) key;
do {
parent = t;
cmp = k.compareTo(t.key);
if (cmp < 0)
t = t.left;
else if (cmp > 0)
t = t.right;
else
return t.setValue(value);
} while (t != null);
}
Entry e = new Entry<>(key, value, parent);
if (cmp < 0)
parent.left = e;
else
parent.right = e;
fixAfterInsertion(e);
size++;
modCount++;
return null;
}
/**
* Removes the mapping for this key from this TreeMap if present.
*
* @param key key for which mapping should be removed
* @return the previous value associated with {@code key}, or
* {@code null} if there was no mapping for {@code key}.
* (A {@code null} return can also indicate that the map
* previously associated {@code null} with {@code key}.)
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
*/
public V remove(Object key) {
Entry p = getEntry(key);
if (p == null)
return null;
V oldValue = p.value;
deleteEntry(p);
return oldValue;
}
/**
* Removes all of the mappings from this map.
* The map will be empty after this call returns.
*/
public void clear() {
modCount++;
size = 0;
root = null;
}
/**
* Returns a shallow copy of this {@code TreeMap} instance. (The keys and
* values themselves are not cloned.)
*
* @return a shallow copy of this map
*/
public Object clone() {
TreeMap clone = null;
try {
clone = (TreeMap) super.clone();
} catch (CloneNotSupportedException e) {
throw new InternalError();
}
// Put clone into "virgin" state (except for comparator)
clone.root = null;
clone.size = 0;
clone.modCount = 0;
clone.entrySet = null;
clone.navigableKeySet = null;
clone.descendingMap = null;
// Initialize clone with our mappings
try {
clone.buildFromSorted(size, entrySet().iterator(), null, null);
} catch (java.io.IOException cannotHappen) {
} catch (ClassNotFoundException cannotHappen) {
}
return clone;
}
// NavigableMap API methods
/**
* @since 1.6
*/
public Map.Entry firstEntry() {
return exportEntry(getFirstEntry());
}
/**
* @since 1.6
*/
public Map.Entry lastEntry() {
return exportEntry(getLastEntry());
}
/**
* @since 1.6
*/
public Map.Entry pollFirstEntry() {
Entry p = getFirstEntry();
Map.Entry result = exportEntry(p);
if (p != null)
deleteEntry(p);
return result;
}
/**
* @since 1.6
*/
public Map.Entry pollLastEntry() {
Entry p = getLastEntry();
Map.Entry result = exportEntry(p);
if (p != null)
deleteEntry(p);
return result;
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @since 1.6
*/
public Map.Entry lowerEntry(K key) {
return exportEntry(getLowerEntry(key));
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @since 1.6
*/
public K lowerKey(K key) {
return keyOrNull(getLowerEntry(key));
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @since 1.6
*/
public Map.Entry floorEntry(K key) {
return exportEntry(getFloorEntry(key));
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @since 1.6
*/
public K floorKey(K key) {
return keyOrNull(getFloorEntry(key));
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @since 1.6
*/
public Map.Entry ceilingEntry(K key) {
return exportEntry(getCeilingEntry(key));
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @since 1.6
*/
public K ceilingKey(K key) {
return keyOrNull(getCeilingEntry(key));
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @since 1.6
*/
public Map.Entry higherEntry(K key) {
return exportEntry(getHigherEntry(key));
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @since 1.6
*/
public K higherKey(K key) {
return keyOrNull(getHigherEntry(key));
}
// Views
/**
* Fields initialized to contain an instance of the entry set view
* the first time this view is requested. Views are stateless, so
* there's no reason to create more than one.
*/
private transient EntrySet entrySet = null;
private transient KeySet navigableKeySet = null;
private transient NavigableMap descendingMap = null;
/**
* Returns a {@link Set} view of the keys contained in this map.
* The set's iterator returns the keys in ascending order.
* The set is backed by the map, so changes to the map are
* reflected in the set, and vice-versa. If the map is modified
* while an iteration over the set is in progress (except through
* the iterator's own {@code remove} operation), the results of
* the iteration are undefined. The set supports element removal,
* which removes the corresponding mapping from the map, via the
* {@code Iterator.remove}, {@code Set.remove},
* {@code removeAll}, {@code retainAll}, and {@code clear}
* operations. It does not support the {@code add} or {@code addAll}
* operations.
*/
public Set keySet() {
return navigableKeySet();
}
/**
* @since 1.6
*/
public NavigableSet navigableKeySet() {
KeySet nks = navigableKeySet;
return (nks != null) ? nks : (navigableKeySet = new KeySet(this));
}
/**
* @since 1.6
*/
public NavigableSet descendingKeySet() {
return descendingMap().navigableKeySet();
}
/**
* Returns a {@link Collection} view of the values contained in this map.
* The collection's iterator returns the values in ascending order
* of the corresponding keys.
* The collection is backed by the map, so changes to the map are
* reflected in the collection, and vice-versa. If the map is
* modified while an iteration over the collection is in progress
* (except through the iterator's own {@code remove} operation),
* the results of the iteration are undefined. The collection
* supports element removal, which removes the corresponding
* mapping from the map, via the {@code Iterator.remove},
* {@code Collection.remove}, {@code removeAll},
* {@code retainAll} and {@code clear} operations. It does not
* support the {@code add} or {@code addAll} operations.
*/
public Collection values() {
Collection vs = values;
return (vs != null) ? vs : (values = new Values());
}
/**
* Returns a {@link Set} view of the mappings contained in this map.
* The set's iterator returns the entries in ascending key order.
* The set is backed by the map, so changes to the map are
* reflected in the set, and vice-versa. If the map is modified
* while an iteration over the set is in progress (except through
* the iterator's own {@code remove} operation, or through the
* {@code setValue} operation on a map entry returned by the
* iterator) the results of the iteration are undefined. The set
* supports element removal, which removes the corresponding
* mapping from the map, via the {@code Iterator.remove},
* {@code Set.remove}, {@code removeAll}, {@code retainAll} and
* {@code clear} operations. It does not support the
* {@code add} or {@code addAll} operations.
*/
public Set> entrySet() {
EntrySet es = entrySet;
return (es != null) ? es : (entrySet = new EntrySet());
}
/**
* @since 1.6
*/
public NavigableMap descendingMap() {
NavigableMap km = descendingMap;
return (km != null) ? km :
(descendingMap = new DescendingSubMap(this,
true, null, true,
true, null, true));
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if {@code fromKey} or {@code toKey} is
* null and this map uses natural ordering, or its comparator
* does not permit null keys
* @throws IllegalArgumentException {@inheritDoc}
* @since 1.6
*/
public NavigableMap subMap(K fromKey, boolean fromInclusive,
K toKey, boolean toInclusive) {
return new AscendingSubMap(this,
false, fromKey, fromInclusive,
false, toKey, toInclusive);
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if {@code toKey} is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @throws IllegalArgumentException {@inheritDoc}
* @since 1.6
*/
public NavigableMap headMap(K toKey, boolean inclusive) {
return new AscendingSubMap(this,
true, null, true,
false, toKey, inclusive);
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if {@code fromKey} is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @throws IllegalArgumentException {@inheritDoc}
* @since 1.6
*/
public NavigableMap tailMap(K fromKey, boolean inclusive) {
return new AscendingSubMap(this,
false, fromKey, inclusive,
true, null, true);
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if {@code fromKey} or {@code toKey} is
* null and this map uses natural ordering, or its comparator
* does not permit null keys
* @throws IllegalArgumentException {@inheritDoc}
*/
public SortedMap subMap(K fromKey, K toKey) {
return subMap(fromKey, true, toKey, false);
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if {@code toKey} is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @throws IllegalArgumentException {@inheritDoc}
*/
public SortedMap headMap(K toKey) {
return headMap(toKey, false);
}
/**
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException if {@code fromKey} is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
* @throws IllegalArgumentException {@inheritDoc}
*/
public SortedMap tailMap(K fromKey) {
return tailMap(fromKey, true);
}
// View class support
class Values extends AbstractCollection {
public Iterator iterator() {
return new ValueIterator(getFirstEntry());
}
public int size() {
return TreeMap.this.size();
}
public boolean contains(Object o) {
return TreeMap.this.containsValue(o);
}
public boolean remove(Object o) {
for (Entry e = getFirstEntry(); e != null; e = successor(e)) {
if (valEquals(e.getValue(), o)) {
deleteEntry(e);
return true;
}
}
return false;
}
public void clear() {
TreeMap.this.clear();
}
}
class EntrySet extends AbstractSet> {
public Iterator> iterator() {
return new EntryIterator(getFirstEntry());
}
public boolean contains(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry entry = (Map.Entry) o;
V value = entry.getValue();
Entry p = getEntry(entry.getKey());
return p != null && valEquals(p.getValue(), value);
}
public boolean remove(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry entry = (Map.Entry) o;
V value = entry.getValue();
Entry p = getEntry(entry.getKey());
if (p != null && valEquals(p.getValue(), value)) {
deleteEntry(p);
return true;
}
return false;
}
public int size() {
return TreeMap.this.size();
}
public void clear() {
TreeMap.this.clear();
}
}
/*
* Unlike Values and EntrySet, the KeySet class is static,
* delegating to a NavigableMap to allow use by SubMaps, which
* outweighs the ugliness of needing type-tests for the following
* Iterator methods that are defined appropriately in main versus
* submap classes.
*/
Iterator keyIterator() {
return new KeyIterator(getFirstEntry());
}
Iterator descendingKeyIterator() {
return new DescendingKeyIterator(getLastEntry());
}
static final class KeySet extends AbstractSet implements NavigableSet {
private final NavigableMap m;
KeySet(NavigableMap map) { m = map; }
public Iterator iterator() {
if (m instanceof TreeMap)
return ((TreeMap)m).keyIterator();
else
return (Iterator)(((TreeMap.NavigableSubMap)m).keyIterator());
}
public Iterator descendingIterator() {
if (m instanceof TreeMap)
return ((TreeMap)m).descendingKeyIterator();
else
return (Iterator)(((TreeMap.NavigableSubMap)m).descendingKeyIterator());
}
public int size() { return m.size(); }
public boolean isEmpty() { return m.isEmpty(); }
public boolean contains(Object o) { return m.containsKey(o); }
public void clear() { m.clear(); }
public E lower(E e) { return m.lowerKey(e); }
public E floor(E e) { return m.floorKey(e); }
public E ceiling(E e) { return m.ceilingKey(e); }
public E higher(E e) { return m.higherKey(e); }
public E first() { return m.firstKey(); }
public E last() { return m.lastKey(); }
public Comparator comparator() { return m.comparator(); }
public E pollFirst() {
Map.Entry e = m.pollFirstEntry();
return (e == null) ? null : e.getKey();
}
public E pollLast() {
Map.Entry e = m.pollLastEntry();
return (e == null) ? null : e.getKey();
}
public boolean remove(Object o) {
int oldSize = size();
m.remove(o);
return size() != oldSize;
}
public NavigableSet subSet(E fromElement, boolean fromInclusive,
E toElement, boolean toInclusive) {
return new KeySet<>(m.subMap(fromElement, fromInclusive,
toElement, toInclusive));
}
public NavigableSet headSet(E toElement, boolean inclusive) {
return new KeySet<>(m.headMap(toElement, inclusive));
}
public NavigableSet tailSet(E fromElement, boolean inclusive) {
return new KeySet<>(m.tailMap(fromElement, inclusive));
}
public SortedSet subSet(E fromElement, E toElement) {
return subSet(fromElement, true, toElement, false);
}
public SortedSet headSet(E toElement) {
return headSet(toElement, false);
}
public SortedSet tailSet(E fromElement) {
return tailSet(fromElement, true);
}
public NavigableSet descendingSet() {
return new KeySet(m.descendingMap());
}
}
/**
* Base class for TreeMap Iterators
*/
abstract class PrivateEntryIterator implements Iterator {
Entry next;
Entry lastReturned;
int expectedModCount;
PrivateEntryIterator(Entry first) {
expectedModCount = modCount;
lastReturned = null;
next = first;
}
public final boolean hasNext() {
return next != null;
}
final Entry nextEntry() {
Entry e = next;
if (e == null)
throw new NoSuchElementException();
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
next = successor(e);
lastReturned = e;
return e;
}
final Entry prevEntry() {
Entry e = next;
if (e == null)
throw new NoSuchElementException();
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
next = predecessor(e);
lastReturned = e;
return e;
}
public void remove() {
if (lastReturned == null)
throw new IllegalStateException();
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
// deleted entries are replaced by their successors
if (lastReturned.left != null && lastReturned.right != null)
next = lastReturned;
deleteEntry(lastReturned);
expectedModCount = modCount;
lastReturned = null;
}
}
final class EntryIterator extends PrivateEntryIterator> {
EntryIterator(Entry first) {
super(first);
}
public Map.Entry next() {
return nextEntry();
}
}
final class ValueIterator extends PrivateEntryIterator {
ValueIterator(Entry first) {
super(first);
}
public V next() {
return nextEntry().value;
}
}
final class KeyIterator extends PrivateEntryIterator {
KeyIterator(Entry first) {
super(first);
}
public K next() {
return nextEntry().key;
}
}
final class DescendingKeyIterator extends PrivateEntryIterator {
DescendingKeyIterator(Entry first) {
super(first);
}
public K next() {
return prevEntry().key;
}
}
// Little utilities
/**
* Compares two keys using the correct comparison method for this TreeMap.
*/
final int compare(Object k1, Object k2) {
return comparator==null ? ((Comparable)k1).compareTo((K)k2)
: comparator.compare((K)k1, (K)k2);
}
/**
* Test two values for equality. Differs from o1.equals(o2) only in
* that it copes with {@code null} o1 properly.
*/
static final boolean valEquals(Object o1, Object o2) {
return (o1==null ? o2==null : o1.equals(o2));
}
/**
* Return SimpleImmutableEntry for entry, or null if null
*/
static Map.Entry exportEntry(TreeMap.Entry e) {
return (e == null) ? null :
new AbstractMap.SimpleImmutableEntry<>(e);
}
/**
* Return key for entry, or null if null
*/
static K keyOrNull(TreeMap.Entry e) {
return (e == null) ? null : e.key;
}
/**
* Returns the key corresponding to the specified Entry.
* @throws NoSuchElementException if the Entry is null
*/
static K key(Entry e) {
if (e==null)
throw new NoSuchElementException();
return e.key;
}
// SubMaps
/**
* Dummy value serving as unmatchable fence key for unbounded
* SubMapIterators
*/
private static final Object UNBOUNDED = new Object();
/**
* @serial include
*/
abstract static class NavigableSubMap extends AbstractMap
implements NavigableMap, java.io.Serializable {
/**
* The backing map.
*/
final TreeMap m;
/**
* Endpoints are represented as triples (fromStart, lo,
* loInclusive) and (toEnd, hi, hiInclusive). If fromStart is
* true, then the low (absolute) bound is the start of the
* backing map, and the other values are ignored. Otherwise,
* if loInclusive is true, lo is the inclusive bound, else lo
* is the exclusive bound. Similarly for the upper bound.
*/
final K lo, hi;
final boolean fromStart, toEnd;
final boolean loInclusive, hiInclusive;
NavigableSubMap(TreeMap m,
boolean fromStart, K lo, boolean loInclusive,
boolean toEnd, K hi, boolean hiInclusive) {
if (!fromStart && !toEnd) {
if (m.compare(lo, hi) > 0)
throw new IllegalArgumentException("fromKey > toKey");
} else {
if (!fromStart) // type check
m.compare(lo, lo);
if (!toEnd)
m.compare(hi, hi);
}
this.m = m;
this.fromStart = fromStart;
this.lo = lo;
this.loInclusive = loInclusive;
this.toEnd = toEnd;
this.hi = hi;
this.hiInclusive = hiInclusive;
}
// internal utilities
final boolean tooLow(Object key) {
if (!fromStart) {
int c = m.compare(key, lo);
if (c < 0 || (c == 0 && !loInclusive))
return true;
}
return false;
}
final boolean tooHigh(Object key) {
if (!toEnd) {
int c = m.compare(key, hi);
if (c > 0 || (c == 0 && !hiInclusive))
return true;
}
return false;
}
final boolean inRange(Object key) {
return !tooLow(key) && !tooHigh(key);
}
final boolean inClosedRange(Object key) {
return (fromStart || m.compare(key, lo) >= 0)
&& (toEnd || m.compare(hi, key) >= 0);
}
final boolean inRange(Object key, boolean inclusive) {
return inclusive ? inRange(key) : inClosedRange(key);
}
/*
* Absolute versions of relation operations.
* Subclasses map to these using like-named "sub"
* versions that invert senses for descending maps
*/
final TreeMap.Entry absLowest() {
TreeMap.Entry e =
(fromStart ? m.getFirstEntry() :
(loInclusive ? m.getCeilingEntry(lo) :
m.getHigherEntry(lo)));
return (e == null || tooHigh(e.key)) ? null : e;
}
final TreeMap.Entry absHighest() {
TreeMap.Entry e =
(toEnd ? m.getLastEntry() :
(hiInclusive ? m.getFloorEntry(hi) :
m.getLowerEntry(hi)));
return (e == null || tooLow(e.key)) ? null : e;
}
final TreeMap.Entry absCeiling(K key) {
if (tooLow(key))
return absLowest();
TreeMap.Entry e = m.getCeilingEntry(key);
return (e == null || tooHigh(e.key)) ? null : e;
}
final TreeMap.Entry absHigher(K key) {
if (tooLow(key))
return absLowest();
TreeMap.Entry e = m.getHigherEntry(key);
return (e == null || tooHigh(e.key)) ? null : e;
}
final TreeMap.Entry absFloor(K key) {
if (tooHigh(key))
return absHighest();
TreeMap.Entry e = m.getFloorEntry(key);
return (e == null || tooLow(e.key)) ? null : e;
}
final TreeMap.Entry absLower(K key) {
if (tooHigh(key))
return absHighest();
TreeMap.Entry e = m.getLowerEntry(key);
return (e == null || tooLow(e.key)) ? null : e;
}
/** Returns the absolute high fence for ascending traversal */
final TreeMap.Entry absHighFence() {
return (toEnd ? null : (hiInclusive ?
m.getHigherEntry(hi) :
m.getCeilingEntry(hi)));
}
/** Return the absolute low fence for descending traversal */
final TreeMap.Entry absLowFence() {
return (fromStart ? null : (loInclusive ?
m.getLowerEntry(lo) :
m.getFloorEntry(lo)));
}
// Abstract methods defined in ascending vs descending classes
// These relay to the appropriate absolute versions
abstract TreeMap.Entry subLowest();
abstract TreeMap.Entry subHighest();
abstract TreeMap.Entry subCeiling(K key);
abstract TreeMap.Entry subHigher(K key);
abstract TreeMap.Entry subFloor(K key);
abstract TreeMap.Entry subLower(K key);
/** Returns ascending iterator from the perspective of this submap */
abstract Iterator keyIterator();
/** Returns descending iterator from the perspective of this submap */
abstract Iterator descendingKeyIterator();
// public methods
public boolean isEmpty() {
return (fromStart && toEnd) ? m.isEmpty() : entrySet().isEmpty();
}
public int size() {
return (fromStart && toEnd) ? m.size() : entrySet().size();
}
public final boolean containsKey(Object key) {
return inRange(key) && m.containsKey(key);
}
public final V put(K key, V value) {
if (!inRange(key))
throw new IllegalArgumentException("key out of range");
return m.put(key, value);
}
public final V get(Object key) {
return !inRange(key) ? null : m.get(key);
}
public final V remove(Object key) {
return !inRange(key) ? null : m.remove(key);
}
public final Map.Entry ceilingEntry(K key) {
return exportEntry(subCeiling(key));
}
public final K ceilingKey(K key) {
return keyOrNull(subCeiling(key));
}
public final Map.Entry higherEntry(K key) {
return exportEntry(subHigher(key));
}
public final K higherKey(K key) {
return keyOrNull(subHigher(key));
}
public final Map.Entry floorEntry(K key) {
return exportEntry(subFloor(key));
}
public final K floorKey(K key) {
return keyOrNull(subFloor(key));
}
public final Map.Entry lowerEntry(K key) {
return exportEntry(subLower(key));
}
public final K lowerKey(K key) {
return keyOrNull(subLower(key));
}
public final K firstKey() {
return key(subLowest());
}
public final K lastKey() {
return key(subHighest());
}
public final Map.Entry firstEntry() {
return exportEntry(subLowest());
}
public final Map.Entry lastEntry() {
return exportEntry(subHighest());
}
public final Map.Entry pollFirstEntry() {
TreeMap.Entry e = subLowest();
Map.Entry result = exportEntry(e);
if (e != null)
m.deleteEntry(e);
return result;
}
public final Map.Entry pollLastEntry() {
TreeMap.Entry e = subHighest();
Map.Entry result = exportEntry(e);
if (e != null)
m.deleteEntry(e);
return result;
}
// Views
transient NavigableMap descendingMapView = null;
transient EntrySetView entrySetView = null;
transient KeySet navigableKeySetView = null;
public final NavigableSet navigableKeySet() {
KeySet nksv = navigableKeySetView;
return (nksv != null) ? nksv :
(navigableKeySetView = new TreeMap.KeySet(this));
}
public final Set keySet() {
return navigableKeySet();
}
public NavigableSet descendingKeySet() {
return descendingMap().navigableKeySet();
}
public final SortedMap subMap(K fromKey, K toKey) {
return subMap(fromKey, true, toKey, false);
}
public final SortedMap headMap(K toKey) {
return headMap(toKey, false);
}
public final SortedMap tailMap(K fromKey) {
return tailMap(fromKey, true);
}
// View classes
abstract class EntrySetView extends AbstractSet> {
private transient int size = -1, sizeModCount;
public int size() {
if (fromStart && toEnd)
return m.size();
if (size == -1 || sizeModCount != m.modCount) {
sizeModCount = m.modCount;
size = 0;
Iterator i = iterator();
while (i.hasNext()) {
size++;
i.next();
}
}
return size;
}
public boolean isEmpty() {
TreeMap.Entry n = absLowest();
return n == null || tooHigh(n.key);
}
public boolean contains(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry entry = (Map.Entry) o;
K key = entry.getKey();
if (!inRange(key))
return false;
TreeMap.Entry node = m.getEntry(key);
return node != null &&
valEquals(node.getValue(), entry.getValue());
}
public boolean remove(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry entry = (Map.Entry) o;
K key = entry.getKey();
if (!inRange(key))
return false;
TreeMap.Entry node = m.getEntry(key);
if (node!=null && valEquals(node.getValue(),
entry.getValue())) {
m.deleteEntry(node);
return true;
}
return false;
}
}
/**
* Iterators for SubMaps
*/
abstract class SubMapIterator implements Iterator {
TreeMap.Entry lastReturned;
TreeMap.Entry next;
final Object fenceKey;
int expectedModCount;
SubMapIterator(TreeMap.Entry first,
TreeMap.Entry fence) {
expectedModCount = m.modCount;
lastReturned = null;
next = first;
fenceKey = fence == null ? UNBOUNDED : fence.key;
}
public final boolean hasNext() {
return next != null && next.key != fenceKey;
}
final TreeMap.Entry nextEntry() {
TreeMap.Entry e = next;
if (e == null || e.key == fenceKey)
throw new NoSuchElementException();
if (m.modCount != expectedModCount)
throw new ConcurrentModificationException();
next = successor(e);
lastReturned = e;
return e;
}
final TreeMap.Entry prevEntry() {
TreeMap.Entry e = next;
if (e == null || e.key == fenceKey)
throw new NoSuchElementException();
if (m.modCount != expectedModCount)
throw new ConcurrentModificationException();
next = predecessor(e);
lastReturned = e;
return e;
}
final void removeAscending() {
if (lastReturned == null)
throw new IllegalStateException();
if (m.modCount != expectedModCount)
throw new ConcurrentModificationException();
// deleted entries are replaced by their successors
if (lastReturned.left != null && lastReturned.right != null)
next = lastReturned;
m.deleteEntry(lastReturned);
lastReturned = null;
expectedModCount = m.modCount;
}
final void removeDescending() {
if (lastReturned == null)
throw new IllegalStateException();
if (m.modCount != expectedModCount)
throw new ConcurrentModificationException();
m.deleteEntry(lastReturned);
lastReturned = null;
expectedModCount = m.modCount;
}
}
final class SubMapEntryIterator extends SubMapIterator> {
SubMapEntryIterator(TreeMap.Entry first,
TreeMap.Entry fence) {
super(first, fence);
}
public Map.Entry next() {
return nextEntry();
}
public void remove() {
removeAscending();
}
}
final class SubMapKeyIterator extends SubMapIterator {
SubMapKeyIterator(TreeMap.Entry first,
TreeMap.Entry fence) {
super(first, fence);
}
public K next() {
return nextEntry().key;
}
public void remove() {
removeAscending();
}
}
final class DescendingSubMapEntryIterator extends SubMapIterator> {
DescendingSubMapEntryIterator(TreeMap.Entry last,
TreeMap.Entry fence) {
super(last, fence);
}
public Map.Entry next() {
return prevEntry();
}
public void remove() {
removeDescending();
}
}
final class DescendingSubMapKeyIterator extends SubMapIterator {
DescendingSubMapKeyIterator(TreeMap.Entry last,
TreeMap.Entry fence) {
super(last, fence);
}
public K next() {
return prevEntry().key;
}
public void remove() {
removeDescending();
}
}
}
/**
* @serial include
*/
static final class AscendingSubMap extends NavigableSubMap {
private static final long serialVersionUID = 912986545866124060L;
AscendingSubMap(TreeMap m,
boolean fromStart, K lo, boolean loInclusive,
boolean toEnd, K hi, boolean hiInclusive) {
super(m, fromStart, lo, loInclusive, toEnd, hi, hiInclusive);
}
public Comparator comparator() {
return m.comparator();
}
public NavigableMap subMap(K fromKey, boolean fromInclusive,
K toKey, boolean toInclusive) {
if (!inRange(fromKey, fromInclusive))
throw new IllegalArgumentException("fromKey out of range");
if (!inRange(toKey, toInclusive))
throw new IllegalArgumentException("toKey out of range");
return new AscendingSubMap(m,
false, fromKey, fromInclusive,
false, toKey, toInclusive);
}
public NavigableMap headMap(K toKey, boolean inclusive) {
if (!inRange(toKey, inclusive))
throw new IllegalArgumentException("toKey out of range");
return new AscendingSubMap(m,
fromStart, lo, loInclusive,
false, toKey, inclusive);
}
public NavigableMap tailMap(K fromKey, boolean inclusive) {
if (!inRange(fromKey, inclusive))
throw new IllegalArgumentException("fromKey out of range");
return new AscendingSubMap(m,
false, fromKey, inclusive,
toEnd, hi, hiInclusive);
}
public NavigableMap descendingMap() {
NavigableMap mv = descendingMapView;
return (mv != null) ? mv :
(descendingMapView =
new DescendingSubMap(m,
fromStart, lo, loInclusive,
toEnd, hi, hiInclusive));
}
Iterator keyIterator() {
return new SubMapKeyIterator(absLowest(), absHighFence());
}
Iterator descendingKeyIterator() {
return new DescendingSubMapKeyIterator(absHighest(), absLowFence());
}
final class AscendingEntrySetView extends EntrySetView {
public Iterator> iterator() {
return new SubMapEntryIterator(absLowest(), absHighFence());
}
}
public Set> entrySet() {
EntrySetView es = entrySetView;
return (es != null) ? es : new AscendingEntrySetView();
}
TreeMap.Entry subLowest() { return absLowest(); }
TreeMap.Entry subHighest() { return absHighest(); }
TreeMap.Entry subCeiling(K key) { return absCeiling(key); }
TreeMap.Entry subHigher(K key) { return absHigher(key); }
TreeMap.Entry subFloor(K key) { return absFloor(key); }
TreeMap.Entry subLower(K key) { return absLower(key); }
}
/**
* @serial include
*/
static final class DescendingSubMap extends NavigableSubMap {
private static final long serialVersionUID = 912986545866120460L;
DescendingSubMap(TreeMap m,
boolean fromStart, K lo, boolean loInclusive,
boolean toEnd, K hi, boolean hiInclusive) {
super(m, fromStart, lo, loInclusive, toEnd, hi, hiInclusive);
}
private final Comparator reverseComparator =
Collections.reverseOrder(m.comparator);
public Comparator comparator() {
return reverseComparator;
}
public NavigableMap subMap(K fromKey, boolean fromInclusive,
K toKey, boolean toInclusive) {
if (!inRange(fromKey, fromInclusive))
throw new IllegalArgumentException("fromKey out of range");
if (!inRange(toKey, toInclusive))
throw new IllegalArgumentException("toKey out of range");
return new DescendingSubMap(m,
false, toKey, toInclusive,
false, fromKey, fromInclusive);
}
public NavigableMap headMap(K toKey, boolean inclusive) {
if (!inRange(toKey, inclusive))
throw new IllegalArgumentException("toKey out of range");
return new DescendingSubMap(m,
false, toKey, inclusive,
toEnd, hi, hiInclusive);
}
public NavigableMap tailMap(K fromKey, boolean inclusive) {
if (!inRange(fromKey, inclusive))
throw new IllegalArgumentException("fromKey out of range");
return new DescendingSubMap(m,
fromStart, lo, loInclusive,
false, fromKey, inclusive);
}
public NavigableMap descendingMap() {
NavigableMap mv = descendingMapView;
return (mv != null) ? mv :
(descendingMapView =
new AscendingSubMap(m,
fromStart, lo, loInclusive,
toEnd, hi, hiInclusive));
}
Iterator keyIterator() {
return new DescendingSubMapKeyIterator(absHighest(), absLowFence());
}
Iterator descendingKeyIterator() {
return new SubMapKeyIterator(absLowest(), absHighFence());
}
final class DescendingEntrySetView extends EntrySetView {
public Iterator> iterator() {
return new DescendingSubMapEntryIterator(absHighest(), absLowFence());
}
}
public Set> entrySet() {
EntrySetView es = entrySetView;
return (es != null) ? es : new DescendingEntrySetView();
}
TreeMap.Entry subLowest() { return absHighest(); }
TreeMap.Entry subHighest() { return absLowest(); }
TreeMap.Entry subCeiling(K key) { return absFloor(key); }
TreeMap.Entry subHigher(K key) { return absLower(key); }
TreeMap.Entry subFloor(K key) { return absCeiling(key); }
TreeMap.Entry subLower(K key) { return absHigher(key); }
}
/**
* This class exists solely for the sake of serialization
* compatibility with previous releases of TreeMap that did not
* support NavigableMap. It translates an old-version SubMap into
* a new-version AscendingSubMap. This class is never otherwise
* used.
*
* @serial include
*/
private class SubMap extends AbstractMap
implements SortedMap, java.io.Serializable {
private static final long serialVersionUID = -6520786458950516097L;
private boolean fromStart = false, toEnd = false;
private K fromKey, toKey;
private Object readResolve() {
return new AscendingSubMap(TreeMap.this,
fromStart, fromKey, true,
toEnd, toKey, false);
}
public Set> entrySet() { throw new InternalError(); }
public K lastKey() { throw new InternalError(); }
public K firstKey() { throw new InternalError(); }
public SortedMap subMap(K fromKey, K toKey) { throw new InternalError(); }
public SortedMap headMap(K toKey) { throw new InternalError(); }
public SortedMap tailMap(K fromKey) { throw new InternalError(); }
public Comparator comparator() { throw new InternalError(); }
}
// Red-black mechanics
private static final boolean RED = false;
private static final boolean BLACK = true;
/**
* Node in the Tree. Doubles as a means to pass key-value pairs back to
* user (see Map.Entry).
*/
static final class Entry implements Map.Entry {
K key;
V value;
Entry left = null;
Entry right = null;
Entry parent;
boolean color = BLACK;
/**
* Make a new cell with given key, value, and parent, and with
* {@code null} child links, and BLACK color.
*/
Entry(K key, V value, Entry parent) {
this.key = key;
this.value = value;
this.parent = parent;
}
/**
* Returns the key.
*
* @return the key
*/
public K getKey() {
return key;
}
/**
* Returns the value associated with the key.
*
* @return the value associated with the key
*/
public V getValue() {
return value;
}
/**
* Replaces the value currently associated with the key with the given
* value.
*
* @return the value associated with the key before this method was
* called
*/
public V setValue(V value) {
V oldValue = this.value;
this.value = value;
return oldValue;
}
public boolean equals(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry e = (Map.Entry)o;
return valEquals(key,e.getKey()) && valEquals(value,e.getValue());
}
public int hashCode() {
int keyHash = (key==null ? 0 : key.hashCode());
int valueHash = (value==null ? 0 : value.hashCode());
return keyHash ^ valueHash;
}
public String toString() {
return key + "=" + value;
}
}
/**
* Returns the first Entry in the TreeMap (according to the TreeMap's
* key-sort function). Returns null if the TreeMap is empty.
*/
final Entry getFirstEntry() {
Entry