Class TreeMap<K,V>

java.lang.Object
java.util.AbstractMap<K,V>
java.util.TreeMap<K,V>
Type Parameters:
K - the type of keys maintained by this map
V - the type of mapped values
All Implemented Interfaces:
Serializable,Cloneable,Map<K,V>,NavigableMap<K,V>,SequencedMap<K,V>,SortedMap<K,V>

public classTreeMap<K,V>extendsAbstractMap<K,V>implementsNavigableMap<K,V>,Cloneable,Serializable
A Red-Black tree basedNavigableMap implementation. The map is sorted according to thenatural ordering of its keys, or by aComparator provided at map creation time, depending on which constructor is used.

This implementation provides guaranteed log(n) time cost for thecontainsKey,get,put andremove operations. Algorithms are adaptations of those in Cormen, Leiserson, and Rivest'sIntroduction 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 beconsistent withequals if this sorted map is to correctly implement theMap interface. (SeeComparable orComparator for a precise definition ofconsistent with equals.) This is so because theMap interface is defined in terms of theequals operation, but a sorted map performs all key comparisons using its compareTo (orcompare) 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 mapis well-defined even if its ordering is inconsistent withequals; it just fails to obey the general contract of theMap 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, itmust 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 theCollections.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 theiterator method of the collections returned by all of this class's "collection view methods" arefail-fast: if the map is structurally modified at any time after the iterator is created, in any way except through the iterator's ownremove method, the iterator will throw aConcurrentModificationException. 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 throwConcurrentModificationException 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.

The methodsceilingEntry(K),firstEntry(),floorEntry(K),higherEntry(K),lastEntry(),lowerEntry(K),pollFirstEntry(), andpollLastEntry() returnMap.Entry instances that represent snapshots of mappings as of the time of the call. They donot support mutation of the underlying map via the optionalsetValue method.

TheputFirst andputLast methods of this class throwUnsupportedOperationException. The encounter order of mappings is determined by the comparison method; therefore, explicit positioning is not supported.

This class is a member of the Java Collections Framework.

Since:
1.2
See Also:
  • Nested Class Summary

    Nested classes/interfaces declared in class java.util.AbstractMap

    AbstractMap.SimpleEntry<K,V>,AbstractMap.SimpleImmutableEntry<K,V>
  • Constructor Summary

    Constructors
    Constructor
    Description
    Constructs a new, empty tree map, using the natural ordering of its keys.
    TreeMap(Comparator<? superK> comparator)
    Constructs a new, empty tree map, ordered according to the given comparator.
    TreeMap(Map<? extendsK, ? extendsV> m)
    Constructs a new tree map containing the same mappings as the given map, ordered according to thenatural ordering of its keys.
    TreeMap(SortedMap<K, ? extendsV> m)
    Constructs a new tree map containing the same mappings and using the same ordering as the specified sorted map.
  • Method Summary

    Modifier and Type
    Method
    Description
    Returns a key-value mapping associated with the least key greater than or equal to the given key, ornull if there is no such key.
    Returns the least key greater than or equal to the given key, ornull if there is no such key.
    void
    Removes all of the mappings from this map.
    Returns a shallow copy of thisTreeMap instance.
    Comparator<? superK>
    Returns the comparator used to order the keys in this map, ornull if this map uses thenatural ordering of its keys.
    compute(K key,BiFunction<? superK, ? superV, ? extendsV> remappingFunction)
    Attempts to compute a mapping for the specified key and its current mapped value, ornull if there is no current mapping (optional operation).
    computeIfAbsent(K key,Function<? superK, ? extendsV> mappingFunction)
    If the specified key is not already associated with a value (or is mapped tonull), attempts to compute its value using the given mapping function and enters it into this map unlessnull (optional operation).
    computeIfPresent(K key,BiFunction<? superK, ? superV, ? extendsV> remappingFunction)
    If the value for the specified key is present and non-null, attempts to compute a new mapping given the key and its current mapped value (optional operation).
    boolean
    Returnstrue if this map contains a mapping for the specified key.
    boolean
    Returnstrue if this map maps one or more keys to the specified value.
    Returns a reverse orderNavigableSet view of the keys contained in this map.
    Returns a reverse order view of the mappings contained in this map.
    Returns aSet view of the mappings contained in this map.
    Returns a key-value mapping associated with the least key in this map, ornull if the map is empty.
    Returns the first (lowest) key currently in this map.
    Returns a key-value mapping associated with the greatest key less than or equal to the given key, ornull if there is no such key.
    floorKey(K key)
    Returns the greatest key less than or equal to the given key, ornull if there is no such key.
    get(Object key)
    Returns the value to which the specified key is mapped, ornull if this map contains no mapping for the key.
    headMap(K toKey)
    Returns a view of the portion of this map whose keys are strictly less thantoKey.
    headMap(K toKey, boolean inclusive)
    Returns a view of the portion of this map whose keys are less than (or equal to, ifinclusive is true)toKey.
    Returns a key-value mapping associated with the least key strictly greater than the given key, ornull if there is no such key.
    higherKey(K key)
    Returns the least key strictly greater than the given key, ornull if there is no such key.
    Returns aSet view of the keys contained in this map.
    Returns a key-value mapping associated with the greatest key in this map, ornull if the map is empty.
    Returns the last (highest) key currently in this map.
    Returns a key-value mapping associated with the greatest key strictly less than the given key, ornull if there is no such key.
    lowerKey(K key)
    Returns the greatest key strictly less than the given key, ornull if there is no such key.
    merge(K key,V value,BiFunction<? superV, ? superV, ? extendsV> remappingFunction)
    If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value (optional operation).
    Returns aNavigableSet view of the keys contained in this map.
    Removes and returns a key-value mapping associated with the least key in this map, ornull if the map is empty (optional operation).
    Removes and returns a key-value mapping associated with the greatest key in this map, ornull if the map is empty (optional operation).
    put(K key,V value)
    Associates the specified value with the specified key in this map.
    void
    putAll(Map<? extendsK, ? extendsV> map)
    Copies all of the mappings from the specified map to this map.
    putFirst(K k,V v)
    ThrowsUnsupportedOperationException.
    putLast(K k,V v)
    ThrowsUnsupportedOperationException.
    Removes the mapping for this key from this TreeMap if present.
    int
    Returns the number of key-value mappings in this map.
    subMap(K fromKey, boolean fromInclusive,K toKey, boolean toInclusive)
    Returns a view of the portion of this map whose keys range fromfromKey totoKey.
    subMap(K fromKey,K toKey)
    Returns a view of the portion of this map whose keys range fromfromKey, inclusive, totoKey, exclusive.
    tailMap(K fromKey)
    Returns a view of the portion of this map whose keys are greater than or equal tofromKey.
    tailMap(K fromKey, boolean inclusive)
    Returns a view of the portion of this map whose keys are greater than (or equal to, ifinclusive is true)fromKey.
    Returns aCollection view of the values contained in this map.

    Methods declared in class java.util.AbstractMap

    equals,hashCode,isEmpty,toString

    Methods declared in class java.lang.Object

    finalize,getClass,notify,notifyAll,wait,wait,wait

    Methods declared in interface java.util.NavigableMap

    reversed

    Methods declared in interface java.util.SequencedMap

    sequencedEntrySet,sequencedKeySet,sequencedValues
  • Constructor Details

    • TreeMap

      public TreeMap()
      Constructs a new, empty tree map, using the natural ordering of its keys. All keys inserted into the map must implement theComparable interface. Furthermore, all such keys must bemutually comparable:k1.compareTo(k2) must not throw aClassCastException for any keysk1 andk2 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), theput(Object key, Object value) call will throw aClassCastException.
    • TreeMap

      public TreeMap(Comparator<? superK> comparator)
      Constructs a new, empty tree map, ordered according to the given comparator. All keys inserted into the map must bemutually comparable by the given comparator:comparator.compare(k1, k2) must not throw aClassCastException for any keysk1 andk2 in the map. If the user attempts to put a key into the map that violates this constraint, theput(Object key, Object value) call will throw aClassCastException.
      Parameters:
      comparator - the comparator that will be used to order this map. Ifnull, thenatural ordering of the keys will be used.
    • TreeMap

      public TreeMap(Map<? extendsK, ? extendsV> m)
      Constructs a new tree map containing the same mappings as the given map, ordered according to thenatural ordering of its keys. All keys inserted into the new map must implement theComparable interface. Furthermore, all such keys must bemutually comparable:k1.compareTo(k2) must not throw aClassCastException for any keysk1 andk2 in the map. This method runs in n*log(n) time.
      Parameters:
      m - the map whose mappings are to be placed in this map
      Throws:
      ClassCastException - if the keys in m are notComparable, or are not mutually comparable
      NullPointerException - if the specified map is null
    • TreeMap

      public TreeMap(SortedMap<K, ? extendsV> 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.
      Parameters:
      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
  • Method Details

    • size

      public int size()
      Returns the number of key-value mappings in this map.
      Specified by:
      size in interface Map<K,V>
      Overrides:
      size in class AbstractMap<K,V>
      Returns:
      the number of key-value mappings in this map
    • containsKey

      public boolean containsKey(Object key)
      Returnstrue if this map contains a mapping for the specified key.
      Specified by:
      containsKey in interface Map<K,V>
      Overrides:
      containsKey in class AbstractMap<K,V>
      Parameters:
      key - key whose presence in this map is to be tested
      Returns:
      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
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
    • containsValue

      public boolean containsValue(Object value)
      Returnstrue if this map maps one or more keys to the specified value. More formally, returnstrue if and only if this map contains at least one mapping to a valuev such that(value==null ? v==null : value.equals(v)). This operation will probably require time linear in the map size for most implementations.
      Specified by:
      containsValue in interface Map<K,V>
      Overrides:
      containsValue in class AbstractMap<K,V>
      Parameters:
      value - value whose presence in this map is to be tested
      Returns:
      true if a mapping tovalue exists;false otherwise
      Since:
      1.2
    • get

      public V get(Object key)
      Returns the value to which the specified key is mapped, ornull if this map contains no mapping for the key.

      More formally, if this map contains a mapping from a keyk to a valuev such thatkey compares equal tok according to the map's ordering, then this method returnsv; otherwise it returnsnull. (There can be at most one such mapping.)

      A return value ofnull does notnecessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key tonull. ThecontainsKey operation may be used to distinguish these two cases.

      Specified by:
      get in interface Map<K,V>
      Overrides:
      get in class AbstractMap<K,V>
      Parameters:
      key - the key whose associated value is to be returned
      Returns:
      the value to which the specified key is mapped, ornull if this map contains no mapping for the key
      Throws:
      ClassCastException - if the specified key cannot be compared with the keys currently in the map
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
    • comparator

      public Comparator<? superK> comparator()
      Description copied from interface: SortedMap
      Returns the comparator used to order the keys in this map, ornull if this map uses thenatural ordering of its keys.
      Specified by:
      comparator in interface SortedMap<K,V>
      Returns:
      the comparator used to order the keys in this map, ornull if this map uses the natural ordering of its keys
    • firstKey

      public K firstKey()
      Description copied from interface: SortedMap
      Returns the first (lowest) key currently in this map.
      Specified by:
      firstKey in interface SortedMap<K,V>
      Returns:
      the first (lowest) key currently in this map
      Throws:
      NoSuchElementException - if this map is empty
    • lastKey

      public K lastKey()
      Description copied from interface: SortedMap
      Returns the last (highest) key currently in this map.
      Specified by:
      lastKey in interface SortedMap<K,V>
      Returns:
      the last (highest) key currently in this map
      Throws:
      NoSuchElementException - if this map is empty
    • putFirst

      public V putFirst(K k,V v)
      ThrowsUnsupportedOperationException. The encounter order induced by this map's comparison method determines the position of mappings, so explicit positioning is not supported.
      Specified by:
      putFirst in interface SequencedMap<K,V>
      Specified by:
      putFirst in interface SortedMap<K,V>
      Parameters:
      k - the key
      v - the value
      Returns:
      the value previously associated with k, or null if none
      Throws:
      UnsupportedOperationException - always
      Since:
      21
    • putLast

      public V putLast(K k,V v)
      ThrowsUnsupportedOperationException. The encounter order induced by this map's comparison method determines the position of mappings, so explicit positioning is not supported.
      Specified by:
      putLast in interface SequencedMap<K,V>
      Specified by:
      putLast in interface SortedMap<K,V>
      Parameters:
      k - the key
      v - the value
      Returns:
      the value previously associated with k, or null if none
      Throws:
      UnsupportedOperationException - always
      Since:
      21
    • putAll

      public void putAll(Map<? extendsK, ? extendsV> 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.
      Specified by:
      putAll in interface Map<K,V>
      Overrides:
      putAll in class AbstractMap<K,V>
      Parameters:
      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
      NullPointerException - if the specified map is null or the specified map contains a null key and this map does not permit null keys
    • put

      public V put(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.
      Specified by:
      put in interface Map<K,V>
      Overrides:
      put in class AbstractMap<K,V>
      Parameters:
      key - key with which the specified value is to be associated
      value - value to be associated with the specified key
      Returns:
      the previous value associated withkey, ornull if there was no mapping forkey. (Anull return can also indicate that the map previously associatednull withkey.)
      Throws:
      ClassCastException - if the specified key cannot be compared with the keys currently in the map
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
    • computeIfAbsent

      public V computeIfAbsent(K key,Function<? superK, ? extendsV> mappingFunction)
      If the specified key is not already associated with a value (or is mapped tonull), attempts to compute its value using the given mapping function and enters it into this map unlessnull (optional operation).

      If the mapping function returnsnull, no mapping is recorded. If the mapping function itself throws an (unchecked) exception, the exception is rethrown, and no mapping is recorded. The most common usage is to construct a new object serving as an initial mapped value or memoized result, as in:

       map.computeIfAbsent(key, k -> new Value(f(k)));

      Or to implement a multi-value map,Map<K,Collection<V>>, supporting multiple values per key:

       map.computeIfAbsent(key, k -> new HashSet<V>()).add(v);

      The mapping function should not modify this map during computation.

      This method will, on a best-effort basis, throw aConcurrentModificationException if it is detected that the mapping function modifies this map during computation.

      Specified by:
      computeIfAbsent in interface Map<K,V>
      Parameters:
      key - key with which the specified value is to be associated
      mappingFunction - the mapping function to compute a value
      Returns:
      the current (existing or computed) value associated with the specified key, or null if the computed value is null
      Throws:
      ConcurrentModificationException - if it is detected that the mapping function modified this map
    • computeIfPresent

      public V computeIfPresent(K key,BiFunction<? superK, ? superV, ? extendsV> remappingFunction)
      If the value for the specified key is present and non-null, attempts to compute a new mapping given the key and its current mapped value (optional operation).

      If the remapping function returnsnull, the mapping is removed. If the remapping function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged.

      The remapping function should not modify this map during computation.

      This method will, on a best-effort basis, throw aConcurrentModificationException if it is detected that the remapping function modifies this map during computation.

      Specified by:
      computeIfPresent in interface Map<K,V>
      Parameters:
      key - key with which the specified value is to be associated
      remappingFunction - the remapping function to compute a value
      Returns:
      the new value associated with the specified key, or null if none
      Throws:
      ConcurrentModificationException - if it is detected that the remapping function modified this map
    • compute

      public V compute(K key,BiFunction<? superK, ? superV, ? extendsV> remappingFunction)
      Attempts to compute a mapping for the specified key and its current mapped value, ornull if there is no current mapping (optional operation). For example, to either create or append aString msg to a value mapping:
       map.compute(key, (k, v) -> (v == null) ? msg : v.concat(msg))
      (Methodmerge() is often simpler to use for such purposes.)

      If the remapping function returnsnull, the mapping is removed (or remains absent if initially absent). If the remapping function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged.

      The remapping function should not modify this map during computation.

      This method will, on a best-effort basis, throw aConcurrentModificationException if it is detected that the remapping function modifies this map during computation.

      Specified by:
      compute in interface Map<K,V>
      Parameters:
      key - key with which the specified value is to be associated
      remappingFunction - the remapping function to compute a value
      Returns:
      the new value associated with the specified key, or null if none
      Throws:
      ConcurrentModificationException - if it is detected that the remapping function modified this map
    • merge

      public V merge(K key,V value,BiFunction<? superV, ? superV, ? extendsV> remappingFunction)
      If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value (optional operation). Otherwise, replaces the associated value with the results of the given remapping function, or removes if the result isnull. This method may be of use when combining multiple mapped values for a key. For example, to either create or append aString msg to a value mapping:
       map.merge(key, msg, String::concat)

      If the remapping function returnsnull, the mapping is removed. If the remapping function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged.

      The remapping function should not modify this map during computation.

      This method will, on a best-effort basis, throw aConcurrentModificationException if it is detected that the remapping function modifies this map during computation.

      Specified by:
      merge in interface Map<K,V>
      Parameters:
      key - key with which the resulting value is to be associated
      value - the non-null value to be merged with the existing value associated with the key or, if no existing value or a null value is associated with the key, to be associated with the key
      remappingFunction - the remapping function to recompute a value if present
      Returns:
      the new value associated with the specified key, or null if no value is associated with the key
      Throws:
      ConcurrentModificationException - if it is detected that the remapping function modified this map
    • remove

      public V remove(Object key)
      Removes the mapping for this key from this TreeMap if present.
      Specified by:
      remove in interface Map<K,V>
      Overrides:
      remove in class AbstractMap<K,V>
      Parameters:
      key - key for which mapping should be removed
      Returns:
      the previous value associated withkey, ornull if there was no mapping forkey. (Anull return can also indicate that the map previously associatednull withkey.)
      Throws:
      ClassCastException - if the specified key cannot be compared with the keys currently in the map
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
    • clear

      public void clear()
      Removes all of the mappings from this map. The map will be empty after this call returns.
      Specified by:
      clear in interface Map<K,V>
      Overrides:
      clear in class AbstractMap<K,V>
    • clone

      public Object clone()
      Returns a shallow copy of thisTreeMap instance. (The keys and values themselves are not cloned.)
      Overrides:
      clone in class AbstractMap<K,V>
      Returns:
      a shallow copy of this map
      See Also:
    • firstEntry

      public Map.Entry<K,V> firstEntry()
      Description copied from interface: NavigableMap
      Returns a key-value mapping associated with the least key in this map, ornull if the map is empty.
      Specified by:
      firstEntry in interface NavigableMap<K,V>
      Specified by:
      firstEntry in interface SequencedMap<K,V>
      Returns:
      an entry with the least key, ornull if this map is empty
      Since:
      1.6
    • lastEntry

      public Map.Entry<K,V> lastEntry()
      Description copied from interface: NavigableMap
      Returns a key-value mapping associated with the greatest key in this map, ornull if the map is empty.
      Specified by:
      lastEntry in interface NavigableMap<K,V>
      Specified by:
      lastEntry in interface SequencedMap<K,V>
      Returns:
      an entry with the greatest key, ornull if this map is empty
      Since:
      1.6
    • pollFirstEntry

      public Map.Entry<K,V> pollFirstEntry()
      Description copied from interface: NavigableMap
      Removes and returns a key-value mapping associated with the least key in this map, ornull if the map is empty (optional operation).
      Specified by:
      pollFirstEntry in interface NavigableMap<K,V>
      Specified by:
      pollFirstEntry in interface SequencedMap<K,V>
      Returns:
      the removed first entry of this map, ornull if this map is empty
      Since:
      1.6
    • pollLastEntry

      public Map.Entry<K,V> pollLastEntry()
      Description copied from interface: NavigableMap
      Removes and returns a key-value mapping associated with the greatest key in this map, ornull if the map is empty (optional operation).
      Specified by:
      pollLastEntry in interface NavigableMap<K,V>
      Specified by:
      pollLastEntry in interface SequencedMap<K,V>
      Returns:
      the removed last entry of this map, ornull if this map is empty
      Since:
      1.6
    • lowerEntry

      public Map.Entry<K,V> lowerEntry(K key)
      Description copied from interface: NavigableMap
      Returns a key-value mapping associated with the greatest key strictly less than the given key, ornull if there is no such key.
      Specified by:
      lowerEntry in interface NavigableMap<K,V>
      Parameters:
      key - the key
      Returns:
      an entry with the greatest key less thankey, ornull if there is no such key
      Throws:
      ClassCastException - if the specified key cannot be compared with the keys currently in the map
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
      Since:
      1.6
    • lowerKey

      public K lowerKey(K key)
      Description copied from interface: NavigableMap
      Returns the greatest key strictly less than the given key, ornull if there is no such key.
      Specified by:
      lowerKey in interface NavigableMap<K,V>
      Parameters:
      key - the key
      Returns:
      the greatest key less thankey, ornull if there is no such key
      Throws:
      ClassCastException - if the specified key cannot be compared with the keys currently in the map
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
      Since:
      1.6
    • floorEntry

      public Map.Entry<K,V> floorEntry(K key)
      Description copied from interface: NavigableMap
      Returns a key-value mapping associated with the greatest key less than or equal to the given key, ornull if there is no such key.
      Specified by:
      floorEntry in interface NavigableMap<K,V>
      Parameters:
      key - the key
      Returns:
      an entry with the greatest key less than or equal tokey, ornull if there is no such key
      Throws:
      ClassCastException - if the specified key cannot be compared with the keys currently in the map
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
      Since:
      1.6
    • floorKey

      public K floorKey(K key)
      Description copied from interface: NavigableMap
      Returns the greatest key less than or equal to the given key, ornull if there is no such key.
      Specified by:
      floorKey in interface NavigableMap<K,V>
      Parameters:
      key - the key
      Returns:
      the greatest key less than or equal tokey, ornull if there is no such key
      Throws:
      ClassCastException - if the specified key cannot be compared with the keys currently in the map
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
      Since:
      1.6
    • ceilingEntry

      public Map.Entry<K,V> ceilingEntry(K key)
      Description copied from interface: NavigableMap
      Returns a key-value mapping associated with the least key greater than or equal to the given key, ornull if there is no such key.
      Specified by:
      ceilingEntry in interface NavigableMap<K,V>
      Parameters:
      key - the key
      Returns:
      an entry with the least key greater than or equal tokey, ornull if there is no such key
      Throws:
      ClassCastException - if the specified key cannot be compared with the keys currently in the map
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
      Since:
      1.6
    • ceilingKey

      public K ceilingKey(K key)
      Description copied from interface: NavigableMap
      Returns the least key greater than or equal to the given key, ornull if there is no such key.
      Specified by:
      ceilingKey in interface NavigableMap<K,V>
      Parameters:
      key - the key
      Returns:
      the least key greater than or equal tokey, ornull if there is no such key
      Throws:
      ClassCastException - if the specified key cannot be compared with the keys currently in the map
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
      Since:
      1.6
    • higherEntry

      public Map.Entry<K,V> higherEntry(K key)
      Description copied from interface: NavigableMap
      Returns a key-value mapping associated with the least key strictly greater than the given key, ornull if there is no such key.
      Specified by:
      higherEntry in interface NavigableMap<K,V>
      Parameters:
      key - the key
      Returns:
      an entry with the least key greater thankey, ornull if there is no such key
      Throws:
      ClassCastException - if the specified key cannot be compared with the keys currently in the map
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
      Since:
      1.6
    • higherKey

      public K higherKey(K key)
      Description copied from interface: NavigableMap
      Returns the least key strictly greater than the given key, ornull if there is no such key.
      Specified by:
      higherKey in interface NavigableMap<K,V>
      Parameters:
      key - the key
      Returns:
      the least key greater thankey, ornull if there is no such key
      Throws:
      ClassCastException - if the specified key cannot be compared with the keys currently in the map
      NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys
      Since:
      1.6
    • keySet

      public Set<K> keySet()
      Returns aSet view of the keys contained in this map.

      The set's iterator returns the keys in ascending order. The set's spliterator islate-binding,fail-fast, and additionally reportsSpliterator.SORTED andSpliterator.ORDERED with an encounter order that is ascending key order. The spliterator's comparator (seeSpliterator.getComparator()) isnull if the tree map's comparator (seecomparator()) isnull. Otherwise, the spliterator's comparator is the same as or imposes the same total ordering as the tree map's comparator.

      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 ownremove operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via theIterator.remove,Set.remove,removeAll,retainAll, andclear operations. It does not support theadd oraddAll operations.

      Specified by:
      keySet in interface Map<K,V>
      Specified by:
      keySet in interface SortedMap<K,V>
      Overrides:
      keySet in class AbstractMap<K,V>
      Returns:
      a set view of the keys contained in this map
    • navigableKeySet

      public NavigableSet<K> navigableKeySet()
      Description copied from interface: NavigableMap
      Returns aNavigableSet 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 theIterator.remove,Set.remove,removeAll,retainAll, andclear operations. It does not support theadd oraddAll operations.
      Specified by:
      navigableKeySet in interface NavigableMap<K,V>
      Returns:
      a navigable set view of the keys in this map
      Since:
      1.6
    • descendingKeySet

      public NavigableSet<K> descendingKeySet()
      Description copied from interface: NavigableMap
      Returns a reverse orderNavigableSet view of the keys contained in this map. The set's iterator returns the keys in descending 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 theIterator.remove,Set.remove,removeAll,retainAll, andclear operations. It does not support theadd oraddAll operations.
      Specified by:
      descendingKeySet in interface NavigableMap<K,V>
      Returns:
      a reverse order navigable set view of the keys in this map
      Since:
      1.6
    • values

      public Collection<V> values()
      Returns aCollection view of the values contained in this map.

      The collection's iterator returns the values in ascending order of the corresponding keys. The collection's spliterator islate-binding,fail-fast, and additionally reportsSpliterator.ORDERED with an encounter order that is 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 ownremove operation), the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via theIterator.remove,Collection.remove,removeAll,retainAll andclear operations. It does not support theadd oraddAll operations.

      Specified by:
      values in interface Map<K,V>
      Specified by:
      values in interface SortedMap<K,V>
      Overrides:
      values in class AbstractMap<K,V>
      Returns:
      a collection view of the values contained in this map
    • entrySet

      public Set<Map.Entry<K,V>> entrySet()
      Returns aSet view of the mappings contained in this map.

      The set's iterator returns the entries in ascending key order. The set's spliterator islate-binding,fail-fast, and additionally reportsSpliterator.SORTED andSpliterator.ORDERED with an encounter order that is 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 ownremove operation, or through thesetValue 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 theIterator.remove,Set.remove,removeAll,retainAll andclear operations. It does not support theadd oraddAll operations.

      Specified by:
      entrySet in interface Map<K,V>
      Specified by:
      entrySet in interface SortedMap<K,V>
      Returns:
      a set view of the mappings contained in this map, sorted in ascending key order
    • descendingMap

      public NavigableMap<K,V> descendingMap()
      Description copied from interface: NavigableMap
      Returns a reverse order view of the mappings contained in this map. The descending map is backed by this map, so changes to the map are reflected in the descending map, and vice-versa. If either map is modified while an iteration over a collection view of either map is in progress (except through the iterator's ownremove operation), the results of the iteration are undefined.

      The returned map has an ordering equivalent toCollections.reverseOrder(comparator()). The expressionm.descendingMap().descendingMap() returns a view ofm essentially equivalent tom.

      Specified by:
      descendingMap in interface NavigableMap<K,V>
      Returns:
      a reverse order view of this map
      Since:
      1.6
    • subMap

      public NavigableMap<K,V> subMap(K fromKey, boolean fromInclusive,K toKey, boolean toInclusive)
      Description copied from interface: NavigableMap
      Returns a view of the portion of this map whose keys range fromfromKey totoKey. IffromKey andtoKey are equal, the returned map is empty unlessfromInclusive andtoInclusive are both true. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.

      The returned map will throw anIllegalArgumentException on an attempt to insert a key outside of its range, or to construct a submap either of whose endpoints lie outside its range.

      Specified by:
      subMap in interface NavigableMap<K,V>
      Parameters:
      fromKey - low endpoint of the keys in the returned map
      fromInclusive -true if the low endpoint is to be included in the returned view
      toKey - high endpoint of the keys in the returned map
      toInclusive -true if the high endpoint is to be included in the returned view
      Returns:
      a view of the portion of this map whose keys range fromfromKey totoKey
      Throws:
      ClassCastException - iffromKey andtoKey cannot be compared to one another using this map's comparator (or, if the map has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception iffromKey ortoKey cannot be compared to keys currently in the map.
      NullPointerException - iffromKey ortoKey is null and this map uses natural ordering, or its comparator does not permit null keys
      IllegalArgumentException - iffromKey is greater thantoKey; or if this map itself has a restricted range, andfromKey ortoKey lies outside the bounds of the range
      Since:
      1.6
    • headMap

      public NavigableMap<K,V> headMap(K toKey, boolean inclusive)
      Description copied from interface: NavigableMap
      Returns a view of the portion of this map whose keys are less than (or equal to, ifinclusive is true)toKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.

      The returned map will throw anIllegalArgumentException on an attempt to insert a key outside its range.

      Specified by:
      headMap in interface NavigableMap<K,V>
      Parameters:
      toKey - high endpoint of the keys in the returned map
      inclusive -true if the high endpoint is to be included in the returned view
      Returns:
      a view of the portion of this map whose keys are less than (or equal to, ifinclusive is true)toKey
      Throws:
      ClassCastException - iftoKey is not compatible with this map's comparator (or, if the map has no comparator, iftoKey does not implementComparable). Implementations may, but are not required to, throw this exception iftoKey cannot be compared to keys currently in the map.
      NullPointerException - iftoKey is null and this map uses natural ordering, or its comparator does not permit null keys
      IllegalArgumentException - if this map itself has a restricted range, andtoKey lies outside the bounds of the range
      Since:
      1.6
    • tailMap

      public NavigableMap<K,V> tailMap(K fromKey, boolean inclusive)
      Description copied from interface: NavigableMap
      Returns a view of the portion of this map whose keys are greater than (or equal to, ifinclusive is true)fromKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.

      The returned map will throw anIllegalArgumentException on an attempt to insert a key outside its range.

      Specified by:
      tailMap in interface NavigableMap<K,V>
      Parameters:
      fromKey - low endpoint of the keys in the returned map
      inclusive -true if the low endpoint is to be included in the returned view
      Returns:
      a view of the portion of this map whose keys are greater than (or equal to, ifinclusive is true)fromKey
      Throws:
      ClassCastException - iffromKey is not compatible with this map's comparator (or, if the map has no comparator, iffromKey does not implementComparable). Implementations may, but are not required to, throw this exception iffromKey cannot be compared to keys currently in the map.
      NullPointerException - iffromKey is null and this map uses natural ordering, or its comparator does not permit null keys
      IllegalArgumentException - if this map itself has a restricted range, andfromKey lies outside the bounds of the range
      Since:
      1.6
    • subMap

      public SortedMap<K,V> subMap(K fromKey,K toKey)
      Description copied from interface: NavigableMap
      Returns a view of the portion of this map whose keys range fromfromKey, inclusive, totoKey, exclusive. (IffromKey andtoKey are equal, the returned map is empty.) The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.

      The returned map will throw anIllegalArgumentException on an attempt to insert a key outside its range.

      Equivalent tosubMap(fromKey, true, toKey, false).

      Specified by:
      subMap in interface NavigableMap<K,V>
      Specified by:
      subMap in interface SortedMap<K,V>
      Parameters:
      fromKey - low endpoint (inclusive) of the keys in the returned map
      toKey - high endpoint (exclusive) of the keys in the returned map
      Returns:
      a view of the portion of this map whose keys range fromfromKey, inclusive, totoKey, exclusive
      Throws:
      ClassCastException - iffromKey andtoKey cannot be compared to one another using this map's comparator (or, if the map has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception iffromKey ortoKey cannot be compared to keys currently in the map.
      NullPointerException - iffromKey ortoKey is null and this map uses natural ordering, or its comparator does not permit null keys
      IllegalArgumentException - iffromKey is greater thantoKey; or if this map itself has a restricted range, andfromKey ortoKey lies outside the bounds of the range
    • headMap

      public SortedMap<K,V> headMap(K toKey)
      Description copied from interface: NavigableMap
      Returns a view of the portion of this map whose keys are strictly less thantoKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.

      The returned map will throw anIllegalArgumentException on an attempt to insert a key outside its range.

      Equivalent toheadMap(toKey, false).

      Specified by:
      headMap in interface NavigableMap<K,V>
      Specified by:
      headMap in interface SortedMap<K,V>
      Parameters:
      toKey - high endpoint (exclusive) of the keys in the returned map
      Returns:
      a view of the portion of this map whose keys are strictly less thantoKey
      Throws:
      ClassCastException - iftoKey is not compatible with this map's comparator (or, if the map has no comparator, iftoKey does not implementComparable). Implementations may, but are not required to, throw this exception iftoKey cannot be compared to keys currently in the map.
      NullPointerException - iftoKey is null and this map uses natural ordering, or its comparator does not permit null keys
      IllegalArgumentException - if this map itself has a restricted range, andtoKey lies outside the bounds of the range
    • tailMap

      public SortedMap<K,V> tailMap(K fromKey)
      Description copied from interface: NavigableMap
      Returns a view of the portion of this map whose keys are greater than or equal tofromKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.

      The returned map will throw anIllegalArgumentException on an attempt to insert a key outside its range.

      Equivalent totailMap(fromKey, true).

      Specified by:
      tailMap in interface NavigableMap<K,V>
      Specified by:
      tailMap in interface SortedMap<K,V>
      Parameters:
      fromKey - low endpoint (inclusive) of the keys in the returned map
      Returns:
      a view of the portion of this map whose keys are greater than or equal tofromKey
      Throws:
      ClassCastException - iffromKey is not compatible with this map's comparator (or, if the map has no comparator, iffromKey does not implementComparable). Implementations may, but are not required to, throw this exception iffromKey cannot be compared to keys currently in the map.
      NullPointerException - iffromKey is null and this map uses natural ordering, or its comparator does not permit null keys
      IllegalArgumentException - if this map itself has a restricted range, andfromKey lies outside the bounds of the range