FileDocCategorySizeDatePackage
TreeMap.javaAPI DocJava SE 6 API85411Tue Jun 10 00:25:56 BST 2008java.util

TreeMap

public class TreeMap extends AbstractMap implements NavigableMap, Cloneable, Serializable
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 containsKey, get, put and remove operations. Algorithms are adaptations of those in Cormen, Leiserson, and Rivest's Introduction to Algorithms.

Note that the ordering maintained by a sorted map (whether or not an explicit comparator is provided) must be consistent with equals if this sorted map is to correctly implement the Map interface. (See Comparable or Comparator for a precise definition of consistent with equals.) This is so because the Map interface is defined in terms of the equals operation, but a map performs all key comparisons using its compareTo (or 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 equals; it just fails to obey the general contract of the 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 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 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 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 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 Entry.setValue method. (Note however that it is possible to change mappings in the associated map using 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
version
1.73, 05/10/06
see
Map
see
HashMap
see
Hashtable
see
Comparable
see
Comparator
see
Collection
since
1.2

Fields Summary
private final Comparator
comparator
The comparator used to maintain order in this tree map, or null if it uses the natural ordering of its keys.
private transient Entry
root
private transient int
size
The number of entries in the tree
private transient int
modCount
The number of structural modifications to the tree.
private transient EntrySet
entrySet
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 KeySet
navigableKeySet
private transient NavigableMap
descendingMap
private static final boolean
RED
private static final boolean
BLACK
private static final long
serialVersionUID
Constructors Summary
public TreeMap()
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: k1.compareTo(k2) must not throw a ClassCastException for any keys k1 and 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 put(Object key, Object value) call will throw a ClassCastException.


                                                                                                      
      
        comparator = null;
public TreeMap(Comparator comparator)
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: comparator.compare(k1, k2) must not throw a ClassCastException for any keys k1 and k2 in the map. If the user attempts to put a key into the map that violates this constraint, the put(Object key, Object value) call will throw a ClassCastException.

param
comparator the comparator that will be used to order this map. If null, the {@linkplain Comparable natural ordering} of the keys will be used.

        this.comparator = comparator;
public TreeMap(Map m)
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: k1.compareTo(k2) must not throw a ClassCastException for any keys k1 and 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

        comparator = null;
        putAll(m);
public TreeMap(SortedMap 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

        comparator = m.comparator();
        try {
            buildFromSorted(m.size(), m.entrySet().iterator(), null, null);
        } catch (java.io.IOException cannotHappen) {
        } catch (ClassNotFoundException cannotHappen) {
        }
Methods Summary
voidaddAllForTreeSet(java.util.SortedSet set, V defaultVal)
Intended to be called only from TreeSet.addAll

	try {
	    buildFromSorted(set.size(), set.iterator(), null, defaultVal);
	} catch (java.io.IOException cannotHappen) {
	} catch (ClassNotFoundException cannotHappen) {
	}
private voidbuildFromSorted(int size, java.util.Iterator it, java.io.ObjectInputStream str, V defaultVal)
Linear time tree building algorithm from sorted data. Can accept keys and/or values from iterator or stream. This leads to too many parameters, but seems better than alternatives. The four formats that this method accepts are: 1) An iterator of Map.Entries. (it != null, defaultVal == null). 2) An iterator of keys. (it != null, defaultVal != null). 3) A stream of alternating serialized keys and values. (it == null, defaultVal == null). 4) A stream of serialized keys. (it == null, defaultVal != null). It is assumed that the comparator of the TreeMap is already set prior to calling this method.

param
size the number of keys (or key-value pairs) to be read from the iterator or stream
param
it If non-null, new entries are created from entries or keys read from this iterator.
param
str If non-null, new entries are created from keys and possibly values read from this stream in serialized form. Exactly one of it and str should be non-null.
param
defaultVal if non-null, this default value is used for each value in the map. If null, each value is read from iterator or stream, as described above.
throws
IOException propagated from stream reads. This cannot occur if str is null.
throws
ClassNotFoundException propagated from readObject. This cannot occur if str is null.

        this.size = size;
        root = buildFromSorted(0, 0, size-1, computeRedLevel(size),
			       it, str, defaultVal);
private final java.util.TreeMap$EntrybuildFromSorted(int level, int lo, int hi, int redLevel, java.util.Iterator it, java.io.ObjectInputStream str, V defaultVal)
Recursive "helper method" that does the real work of the previous method. Identically named parameters have identical definitions. Additional parameters are documented below. It is assumed that the comparator and size fields of the TreeMap are already set prior to calling this method. (It ignores both fields.)

param
level the current level of tree. Initial call should be 0.
param
lo the first element index of this subtree. Initial should be 0.
param
hi the last element index of this subtree. Initial should be size-1.
param
redLevel the level at which nodes should be red. Must be equal to computeRedLevel for tree of this size.

        /*
         * Strategy: The root is the middlemost element. To get to it, we
         * have to first recursively construct the entire left subtree,
         * so as to grab all of its elements. We can then proceed with right
         * subtree.
         *
         * The lo and hi arguments are the minimum and maximum
         * indices to pull out of the iterator or stream for current subtree.
         * They are not actually indexed, we just proceed sequentially,
         * ensuring that items are extracted in corresponding order.
         */

        if (hi < lo) return null;

        int mid = (lo + hi) / 2;

        Entry<K,V> left  = null;
        if (lo < mid)
            left = buildFromSorted(level+1, lo, mid - 1, redLevel,
				   it, str, defaultVal);

        // extract key and/or value from iterator or stream
        K key;
        V value;
        if (it != null) {
            if (defaultVal==null) {
                Map.Entry<K,V> entry = (Map.Entry<K,V>)it.next();
                key = entry.getKey();
                value = entry.getValue();
            } else {
                key = (K)it.next();
                value = defaultVal;
            }
        } else { // use stream
            key = (K) str.readObject();
            value = (defaultVal != null ? defaultVal : (V) str.readObject());
        }

        Entry<K,V> middle =  new Entry<K,V>(key, value, null);

        // color nodes in non-full bottommost level red
        if (level == redLevel)
            middle.color = RED;

        if (left != null) {
            middle.left = left;
            left.parent = middle;
        }

        if (mid < hi) {
            Entry<K,V> right = buildFromSorted(level+1, mid+1, hi, redLevel,
					       it, str, defaultVal);
            middle.right = right;
            right.parent = middle;
        }

        return middle;
public java.util.Map$EntryceilingEntry(K 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

        return exportEntry(getCeilingEntry(key));
public KceilingKey(K 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

        return keyOrNull(getCeilingEntry(key));
public voidclear()
Removes all of the mappings from this map. The map will be empty after this call returns.

        modCount++;
        size = 0;
        root = null;
public java.lang.Objectclone()
Returns a shallow copy of this TreeMap instance. (The keys and values themselves are not cloned.)

return
a shallow copy of this map

        TreeMap<K,V> clone = null;
        try {
            clone = (TreeMap<K,V>) 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;
private static booleancolorOf(java.util.TreeMap$Entry p)
Balancing operations. Implementations of rebalancings during insertion and deletion are slightly different than the CLR version. Rather than using dummy nilnodes, we use a set of accessors that deal properly with null. They are used to avoid messiness surrounding nullness checks in the main algorithms.

        return (p == null ? BLACK : p.color);
public java.util.Comparatorcomparator()

        return comparator;
final intcompare(java.lang.Object k1, java.lang.Object k2)
Compares two keys using the correct comparison method for this TreeMap.

        return comparator==null ? ((Comparable<? super K>)k1).compareTo((K)k2)
            : comparator.compare((K)k1, (K)k2);
private static intcomputeRedLevel(int sz)
Find the level down to which to assign all nodes BLACK. This is the last `full' level of the complete binary tree produced by buildTree. The remaining nodes are colored RED. (This makes a `nice' set of color assignments wrt future insertions.) This level number is computed by finding the number of splits needed to reach the zeroeth node. (The answer is ~lg(N), but in any case must be computed by same quick O(lg(N)) loop.)

        int level = 0;
        for (int m = sz - 1; m >= 0; m = m / 2 - 1)
            level++;
        return level;
public booleancontainsKey(java.lang.Object key)
Returns true if this map contains a mapping for the specified key.

param
key key whose presence in this map is to be tested
return
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

        return getEntry(key) != null;
public booleancontainsValue(java.lang.Object value)
Returns true if this map maps one or more keys to the specified value. More formally, returns true if and only if this map contains at least one mapping to a value v such that (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
true if a mapping to value exists; false otherwise
since
1.2

        for (Entry<K,V> e = getFirstEntry(); e != null; e = successor(e))
            if (valEquals(value, e.value))
                return true;
        return false;
private voiddeleteEntry(java.util.TreeMap$Entry p)
Delete node p, and then rebalance the tree.

        modCount++;
        size--;

        // If strictly internal, copy successor's element to p and then make p
        // point to successor.
        if (p.left != null && p.right != null) {
            Entry<K,V> s = successor (p);
            p.key = s.key;
            p.value = s.value;
            p = s;
        } // p has 2 children

        // Start fixup at replacement node, if it exists.
        Entry<K,V> replacement = (p.left != null ? p.left : p.right);

        if (replacement != null) {
            // Link replacement to parent
            replacement.parent = p.parent;
            if (p.parent == null)
                root = replacement;
            else if (p == p.parent.left)
                p.parent.left  = replacement;
            else
                p.parent.right = replacement;

            // Null out links so they are OK to use by fixAfterDeletion.
            p.left = p.right = p.parent = null;

            // Fix replacement
            if (p.color == BLACK)
                fixAfterDeletion(replacement);
        } else if (p.parent == null) { // return if we are the only node.
            root = null;
        } else { //  No children. Use self as phantom replacement and unlink.
            if (p.color == BLACK)
                fixAfterDeletion(p);

            if (p.parent != null) {
                if (p == p.parent.left)
                    p.parent.left = null;
                else if (p == p.parent.right)
                    p.parent.right = null;
                p.parent = null;
            }
        }
java.util.IteratordescendingKeyIterator()

        return new DescendingKeyIterator(getFirstEntry());
public java.util.NavigableSetdescendingKeySet()

since
1.6

        return descendingMap().navigableKeySet();
public java.util.NavigableMapdescendingMap()

since
1.6

        NavigableMap<K, V> km = descendingMap;
        return (km != null) ? km :
            (descendingMap = new DescendingSubMap(this,
                                                  true, null, true,
                                                  true, null, true));
public java.util.SetentrySet()
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 remove operation, or through the 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 Iterator.remove, Set.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

        EntrySet es = entrySet;
        return (es != null) ? es : (entrySet = new EntrySet());
static java.util.Map$EntryexportEntry(java.util.TreeMap$Entry e)
Return SimpleImmutableEntry for entry, or null if null

        return e == null? null :
            new AbstractMap.SimpleImmutableEntry<K,V>(e);
public java.util.Map$EntryfirstEntry()

since
1.6

        return exportEntry(getFirstEntry());
public KfirstKey()

throws
NoSuchElementException {@inheritDoc}

        return key(getFirstEntry());
private voidfixAfterDeletion(java.util.TreeMap$Entry x)
From CLR

        while (x != root && colorOf(x) == BLACK) {
            if (x == leftOf(parentOf(x))) {
                Entry<K,V> sib = rightOf(parentOf(x));

                if (colorOf(sib) == RED) {
                    setColor(sib, BLACK);
                    setColor(parentOf(x), RED);
                    rotateLeft(parentOf(x));
                    sib = rightOf(parentOf(x));
                }

                if (colorOf(leftOf(sib))  == BLACK &&
                    colorOf(rightOf(sib)) == BLACK) {
                    setColor(sib, RED);
                    x = parentOf(x);
                } else {
                    if (colorOf(rightOf(sib)) == BLACK) {
                        setColor(leftOf(sib), BLACK);
                        setColor(sib, RED);
                        rotateRight(sib);
                        sib = rightOf(parentOf(x));
                    }
                    setColor(sib, colorOf(parentOf(x)));
                    setColor(parentOf(x), BLACK);
                    setColor(rightOf(sib), BLACK);
                    rotateLeft(parentOf(x));
                    x = root;
                }
            } else { // symmetric
                Entry<K,V> sib = leftOf(parentOf(x));

                if (colorOf(sib) == RED) {
                    setColor(sib, BLACK);
                    setColor(parentOf(x), RED);
                    rotateRight(parentOf(x));
                    sib = leftOf(parentOf(x));
                }

                if (colorOf(rightOf(sib)) == BLACK &&
                    colorOf(leftOf(sib)) == BLACK) {
                    setColor(sib, RED);
                    x = parentOf(x);
                } else {
                    if (colorOf(leftOf(sib)) == BLACK) {
                        setColor(rightOf(sib), BLACK);
                        setColor(sib, RED);
                        rotateLeft(sib);
                        sib = leftOf(parentOf(x));
                    }
                    setColor(sib, colorOf(parentOf(x)));
                    setColor(parentOf(x), BLACK);
                    setColor(leftOf(sib), BLACK);
                    rotateRight(parentOf(x));
                    x = root;
                }
            }
        }

        setColor(x, BLACK);
private voidfixAfterInsertion(java.util.TreeMap$Entry x)
From CLR

        x.color = RED;

        while (x != null && x != root && x.parent.color == RED) {
            if (parentOf(x) == leftOf(parentOf(parentOf(x)))) {
                Entry<K,V> y = rightOf(parentOf(parentOf(x)));
                if (colorOf(y) == RED) {
                    setColor(parentOf(x), BLACK);
                    setColor(y, BLACK);
                    setColor(parentOf(parentOf(x)), RED);
                    x = parentOf(parentOf(x));
                } else {
                    if (x == rightOf(parentOf(x))) {
                        x = parentOf(x);
                        rotateLeft(x);
                    }
                    setColor(parentOf(x), BLACK);
                    setColor(parentOf(parentOf(x)), RED);
                    rotateRight(parentOf(parentOf(x)));
                }
            } else {
                Entry<K,V> y = leftOf(parentOf(parentOf(x)));
                if (colorOf(y) == RED) {
                    setColor(parentOf(x), BLACK);
                    setColor(y, BLACK);
                    setColor(parentOf(parentOf(x)), RED);
                    x = parentOf(parentOf(x));
                } else {
                    if (x == leftOf(parentOf(x))) {
                        x = parentOf(x);
                        rotateRight(x);
                    }
                    setColor(parentOf(x), BLACK);
                    setColor(parentOf(parentOf(x)), RED);
                    rotateLeft(parentOf(parentOf(x)));
                }
            }
        }
        root.color = BLACK;
public java.util.Map$EntryfloorEntry(K 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

        return exportEntry(getFloorEntry(key));
public KfloorKey(K 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

        return keyOrNull(getFloorEntry(key));
public Vget(java.lang.Object key)
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

        Entry<K,V> p = getEntry(key);
        return (p==null ? null : p.value);
final java.util.TreeMap$EntrygetCeilingEntry(K key)
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 null.

        Entry<K,V> 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<K,V> parent = p.parent;
                    Entry<K,V> ch = p;
                    while (parent != null && ch == parent.right) {
                        ch = parent;
                        parent = parent.parent;
                    }
                    return parent;
                }
            } else
                return p;
        }
        return null;
final java.util.TreeMap$EntrygetEntry(java.lang.Object key)
Returns this map's entry for the given key, or null if the map does not contain an entry for the key.

return
this map's entry for the given key, or 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

        // Offload comparator-based version for sake of performance
        if (comparator != null)
            return getEntryUsingComparator(key);
        if (key == null)
            throw new NullPointerException();
	Comparable<? super K> k = (Comparable<? super K>) key;
        Entry<K,V> 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;
final java.util.TreeMap$EntrygetEntryUsingComparator(java.lang.Object key)
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.)

	K k = (K) key;
        Comparator<? super K> cpr = comparator;
        if (cpr != null) {
            Entry<K,V> 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;
final java.util.TreeMap$EntrygetFirstEntry()
Returns the first Entry in the TreeMap (according to the TreeMap's key-sort function). Returns null if the TreeMap is empty.

        Entry<K,V> p = root;
        if (p != null)
            while (p.left != null)
                p = p.left;
        return p;
final java.util.TreeMap$EntrygetFloorEntry(K key)
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 null.

        Entry<K,V> 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<K,V> parent = p.parent;
                    Entry<K,V> ch = p;
                    while (parent != null && ch == parent.left) {
                        ch = parent;
                        parent = parent.parent;
                    }
                    return parent;
                }
            } else
                return p;

        }
        return null;
final java.util.TreeMap$EntrygetHigherEntry(K key)
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 null.

        Entry<K,V> 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<K,V> parent = p.parent;
                    Entry<K,V> ch = p;
                    while (parent != null && ch == parent.right) {
                        ch = parent;
                        parent = parent.parent;
                    }
                    return parent;
                }
            }
        }
        return null;
final java.util.TreeMap$EntrygetLastEntry()
Returns the last Entry in the TreeMap (according to the TreeMap's key-sort function). Returns null if the TreeMap is empty.

        Entry<K,V> p = root;
        if (p != null)
            while (p.right != null)
                p = p.right;
        return p;
final java.util.TreeMap$EntrygetLowerEntry(K key)
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 null.

        Entry<K,V> 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<K,V> parent = p.parent;
                    Entry<K,V> ch = p;
                    while (parent != null && ch == parent.left) {
                        ch = parent;
                        parent = parent.parent;
                    }
                    return parent;
                }
            }
        }
        return null;
public java.util.NavigableMapheadMap(K toKey, boolean inclusive)

throws
ClassCastException {@inheritDoc}
throws
NullPointerException if toKey is null and this map uses natural ordering, or its comparator does not permit null keys
throws
IllegalArgumentException {@inheritDoc}
since
1.6

        return new AscendingSubMap(this,
                                   true,  null,  true,
                                   false, toKey, inclusive);
public java.util.SortedMapheadMap(K toKey)

throws
ClassCastException {@inheritDoc}
throws
NullPointerException if toKey is null and this map uses natural ordering, or its comparator does not permit null keys
throws
IllegalArgumentException {@inheritDoc}

        return headMap(toKey, false);
public java.util.Map$EntryhigherEntry(K 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

        return exportEntry(getHigherEntry(key));
public KhigherKey(K 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

        return keyOrNull(getHigherEntry(key));
static Kkey(java.util.TreeMap$Entry e)
Returns the key corresponding to the specified Entry.

throws
NoSuchElementException if the Entry is null

        if (e==null)
            throw new NoSuchElementException();
        return e.key;
java.util.IteratorkeyIterator()

        return new KeyIterator(getFirstEntry());
static KkeyOrNull(java.util.TreeMap$Entry e)
Return key for entry, or null if null

        return e == null? null : e.key;
public java.util.SetkeySet()
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 remove operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.


                                                                                                               
       
        return navigableKeySet();
public java.util.Map$EntrylastEntry()

since
1.6

        return exportEntry(getLastEntry());
public KlastKey()

throws
NoSuchElementException {@inheritDoc}

        return key(getLastEntry());
private static java.util.TreeMap$EntryleftOf(java.util.TreeMap$Entry p)

        return (p == null) ? null: p.left;
public java.util.Map$EntrylowerEntry(K 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

        return exportEntry(getLowerEntry(key));
public KlowerKey(K 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

        return keyOrNull(getLowerEntry(key));
public java.util.NavigableSetnavigableKeySet()

since
1.6

        KeySet<K> nks = navigableKeySet;
        return (nks != null) ? nks : (navigableKeySet = new KeySet(this));
private static java.util.TreeMap$EntryparentOf(java.util.TreeMap$Entry p)

        return (p == null ? null: p.parent);
public java.util.Map$EntrypollFirstEntry()

since
1.6

        Entry<K,V> p = getFirstEntry();
        Map.Entry<K,V> result = exportEntry(p);
        if (p != null)
            deleteEntry(p);
        return result;
public java.util.Map$EntrypollLastEntry()

since
1.6

        Entry<K,V> p = getLastEntry();
        Map.Entry<K,V> result = exportEntry(p);
        if (p != null)
            deleteEntry(p);
        return result;
static java.util.TreeMap$Entrypredecessor(java.util.TreeMap$Entry t)
Returns the predecessor of the specified Entry, or null if no such.

        if (t == null)
            return null;
        else if (t.left != null) {
            Entry<K,V> p = t.left;
            while (p.right != null)
                p = p.right;
            return p;
        } else {
            Entry<K,V> p = t.parent;
            Entry<K,V> ch = t;
            while (p != null && ch == p.left) {
                ch = p;
                p = p.parent;
            }
            return p;
        }
public Vput(K key, V value)
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 key, or null if there was no mapping for key. (A null return can also indicate that the map previously associated null with 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

        Entry<K,V> t = root;
        if (t == null) {
	    // TBD:
	    // 5045147: (coll) Adding null to an empty TreeSet should
	    // throw NullPointerException
	    //
	    // compare(key, key); // type check
            root = new Entry<K,V>(key, value, null);
            size = 1;
            modCount++;
            return null;
        }
        int cmp;
        Entry<K,V> parent;
        // split comparator and comparable paths
        Comparator<? super K> 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<? super K> k = (Comparable<? super K>) 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<K,V> e = new Entry<K,V>(key, value, parent);
        if (cmp < 0)
            parent.left = e;
        else
            parent.right = e;
        fixAfterInsertion(e);
        size++;
        modCount++;
        return null;
public voidputAll(java.util.Map map)
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

        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);
private voidreadObject(java.io.ObjectInputStream s)
Reconstitute the TreeMap instance from a stream (i.e., deserialize it).

        // Read in the Comparator and any hidden stuff
        s.defaultReadObject();

        // Read in size
        int size = s.readInt();

        buildFromSorted(size, null, s, null);
voidreadTreeSet(int size, java.io.ObjectInputStream s, V defaultVal)
Intended to be called only from TreeSet.readObject

        buildFromSorted(size, null, s, defaultVal);
public Vremove(java.lang.Object key)
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 key, or null if there was no mapping for key. (A null return can also indicate that the map previously associated null with 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

        Entry<K,V> p = getEntry(key);
        if (p == null)
            return null;

        V oldValue = p.value;
        deleteEntry(p);
        return oldValue;
private static java.util.TreeMap$EntryrightOf(java.util.TreeMap$Entry p)

        return (p == null) ? null: p.right;
private voidrotateLeft(java.util.TreeMap$Entry p)
From CLR

        if (p != null) {
            Entry<K,V> r = p.right;
            p.right = r.left;
            if (r.left != null)
                r.left.parent = p;
            r.parent = p.parent;
            if (p.parent == null)
                root = r;
            else if (p.parent.left == p)
                p.parent.left = r;
            else
                p.parent.right = r;
            r.left = p;
            p.parent = r;
        }
private voidrotateRight(java.util.TreeMap$Entry p)
From CLR

        if (p != null) {
            Entry<K,V> l = p.left;
            p.left = l.right;
            if (l.right != null) l.right.parent = p;
            l.parent = p.parent;
            if (p.parent == null)
                root = l;
            else if (p.parent.right == p)
                p.parent.right = l;
            else p.parent.left = l;
            l.right = p;
            p.parent = l;
        }
private static voidsetColor(java.util.TreeMap$Entry p, boolean c)

        if (p != null)
	    p.color = c;
public intsize()
Returns the number of key-value mappings in this map.

return
the number of key-value mappings in this map

        return size;
public java.util.NavigableMapsubMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive)

throws
ClassCastException {@inheritDoc}
throws
NullPointerException if fromKey or toKey is null and this map uses natural ordering, or its comparator does not permit null keys
throws
IllegalArgumentException {@inheritDoc}
since
1.6

        return new AscendingSubMap(this,
                                   false, fromKey, fromInclusive,
                                   false, toKey,   toInclusive);
public java.util.SortedMapsubMap(K fromKey, K toKey)

throws
ClassCastException {@inheritDoc}
throws
NullPointerException if fromKey or toKey is null and this map uses natural ordering, or its comparator does not permit null keys
throws
IllegalArgumentException {@inheritDoc}

        return subMap(fromKey, true, toKey, false);
static java.util.TreeMap$Entrysuccessor(java.util.TreeMap$Entry t)
Returns the successor of the specified Entry, or null if no such.

        if (t == null)
            return null;
        else if (t.right != null) {
            Entry<K,V> p = t.right;
            while (p.left != null)
                p = p.left;
            return p;
        } else {
            Entry<K,V> p = t.parent;
            Entry<K,V> ch = t;
            while (p != null && ch == p.right) {
                ch = p;
                p = p.parent;
            }
            return p;
        }
public java.util.NavigableMaptailMap(K fromKey, boolean inclusive)

throws
ClassCastException {@inheritDoc}
throws
NullPointerException if fromKey is null and this map uses natural ordering, or its comparator does not permit null keys
throws
IllegalArgumentException {@inheritDoc}
since
1.6

        return new AscendingSubMap(this,
                                   false, fromKey, inclusive,
                                   true,  null,    true);
public java.util.SortedMaptailMap(K fromKey)

throws
ClassCastException {@inheritDoc}
throws
NullPointerException if fromKey is null and this map uses natural ordering, or its comparator does not permit null keys
throws
IllegalArgumentException {@inheritDoc}

        return tailMap(fromKey, true);
static final booleanvalEquals(java.lang.Object o1, java.lang.Object o2)
Test two values for equality. Differs from o1.equals(o2) only in that it copes with null o1 properly.

        return (o1==null ? o2==null : o1.equals(o2));
public java.util.Collectionvalues()
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 remove operation), the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

        Collection<V> vs = values;
        return (vs != null) ? vs : (values = new Values());
private voidwriteObject(java.io.ObjectOutputStream s)
Save the state of the TreeMap instance to a stream (i.e., serialize it).

serialData
The size of the TreeMap (the number of key-value mappings) is emitted (int), followed by the key (Object) and value (Object) for each key-value mapping represented by the TreeMap. The key-value mappings are emitted in key-order (as determined by the TreeMap's Comparator, or by the keys' natural ordering if the TreeMap has no Comparator).


                                                                                                                                                     
       
          
        // Write out the Comparator and any hidden stuff
        s.defaultWriteObject();

        // Write out size (number of Mappings)
        s.writeInt(size);

        // Write out keys and values (alternating)
        for (Iterator<Map.Entry<K,V>> i = entrySet().iterator(); i.hasNext(); ) {
            Map.Entry<K,V> e = i.next();
            s.writeObject(e.getKey());
            s.writeObject(e.getValue());
        }