Package org.apache.commons.collections

Class SequencedHashMap

  • All Implemented Interfaces:
    java.io.Externalizable, java.io.Serializable, java.lang.Cloneable, java.util.Map
    Direct Known Subclasses:
    LRUMap
    @Deprecated(since="2021-04-30")
public class SequencedHashMap
extends java.lang.Object
implements java.util.Map, java.lang.Cloneable, java.io.Externalizable
    Deprecated.
    Replaced by LinkedMap and ListOrderedMap in map subpackage. Due to be removed in v4.0.
    A map of objects whose mapping entries are sequenced based on the order in which they were added. This data structure has fast O(1) search time, deletion time, and insertion time.

    Although this map is sequenced, it cannot implement List because of incompatible interface definitions. The remove methods in List and Map have different return values (see: List.remove(Object) and Map.remove(Object)).

    This class is not thread safe. When a thread safe implementation is required, use Collections.synchronizedMap(Map) as it is documented, or use explicit synchronization controls.

    Since:
    Commons Collections 2.0
    See Also:
    LinkedMap, ListOrderedMap, Serialized Form

    • Constructor Summary

      Constructors 
      Constructor Description
      SequencedHashMap()
      Deprecated.
      Construct a new sequenced hash map with default initial size and load factor.
      SequencedHashMap​(int initialSize)
      Deprecated.
      Construct a new sequenced hash map with the specified initial size and default load factor.
      SequencedHashMap​(int initialSize, float loadFactor)
      Deprecated.
      Construct a new sequenced hash map with the specified initial size and load factor.
      SequencedHashMap​(java.util.Map m)
      Deprecated.
      Construct a new sequenced hash map and add all the elements in the specified map.

    • Method Summary

      All Methods Instance Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      void clear()
      Deprecated.
      Implements Map.clear().
      java.lang.Object clone()
      Deprecated.
      Creates a shallow copy of this object, preserving the internal structure by copying only references.
      boolean containsKey​(java.lang.Object key)
      Deprecated.
      Implements Map.containsKey(Object).
      boolean containsValue​(java.lang.Object value)
      Deprecated.
      Implements Map.containsValue(Object).
      java.util.Set entrySet()
      Deprecated.
      Implements Map.entrySet().
      boolean equals​(java.lang.Object obj)
      Deprecated.
      Implements Map.equals(Object).
      java.lang.Object get​(int index)
      Deprecated.
      Gets the key at the specified index.
      java.lang.Object get​(java.lang.Object o)
      Deprecated.
      Implements Map.get(Object).
      java.util.Map.Entry getFirst()
      Deprecated.
      Return the entry for the "oldest" mapping.
      java.lang.Object getFirstKey()
      Deprecated.
      Return the key for the "oldest" mapping.
      java.lang.Object getFirstValue()
      Deprecated.
      Return the value for the "oldest" mapping.
      java.util.Map.Entry getLast()
      Deprecated.
      Return the entry for the "newest" mapping.
      java.lang.Object getLastKey()
      Deprecated.
      Return the key for the "newest" mapping.
      java.lang.Object getLastValue()
      Deprecated.
      Return the value for the "newest" mapping.
      java.lang.Object getValue​(int index)
      Deprecated.
      Gets the value at the specified index.
      int hashCode()
      Deprecated.
      Implements Map.hashCode().
      int indexOf​(java.lang.Object key)
      Deprecated.
      Gets the index of the specified key.
      boolean isEmpty()
      Deprecated.
      Implements Map.isEmpty().
      java.util.Iterator iterator()
      Deprecated.
      Gets an iterator over the keys.
      java.util.Set keySet()
      Deprecated.
      Implements Map.keySet().
      int lastIndexOf​(java.lang.Object key)
      Deprecated.
      Gets the last index of the specified key.
      java.lang.Object put​(java.lang.Object key, java.lang.Object value)
      Deprecated.
      Implements Map.put(Object, Object).
      void putAll​(java.util.Map t)
      Deprecated.
      Adds all the mappings in the specified map to this map, replacing any mappings that already exist (as per Map.putAll(Map)).
      void readExternal​(java.io.ObjectInput in)
      Deprecated.
      Deserializes this map from the given stream.
      java.lang.Object remove​(int index)
      Deprecated.
      Removes the element at the specified index.
      java.lang.Object remove​(java.lang.Object key)
      Deprecated.
      Implements Map.remove(Object).
      java.util.List sequence()
      Deprecated.
      Returns a List view of the keys rather than a set view.
      int size()
      Deprecated.
      Implements Map.size().
      java.lang.String toString()
      Deprecated.
      Provides a string representation of the entries within the map.
      java.util.Collection values()
      Deprecated.
      Implements Map.values().
      void writeExternal​(java.io.ObjectOutput out)
      Deprecated.
      Serializes this map to the given stream.

      • Methods inherited from class java.lang.Object

        getClass, notify, notifyAll, wait, wait, wait

      • Methods inherited from interface java.util.Map

        compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

    • Constructor Detail

      • SequencedHashMap

        public SequencedHashMap()
        Deprecated.
        Construct a new sequenced hash map with default initial size and load factor.

      • SequencedHashMap

        public SequencedHashMap​(int initialSize)
        Deprecated.
        Construct a new sequenced hash map with the specified initial size and default load factor.
        Parameters:
        initialSize - the initial size for the hash table
        See Also:
        HashMap(int)

      • SequencedHashMap

        public SequencedHashMap​(int initialSize,
                        float loadFactor)
        Deprecated.
        Construct a new sequenced hash map with the specified initial size and load factor.
        Parameters:
        initialSize - the initial size for the hash table
        loadFactor - the load factor for the hash table.
        See Also:
        HashMap(int,float)

      • SequencedHashMap

        public SequencedHashMap​(java.util.Map m)
        Deprecated.
        Construct a new sequenced hash map and add all the elements in the specified map. The order in which the mappings in the specified map are added is defined by putAll(Map).

    • Method Detail

      • size

        public int size()
        Deprecated.
        Implements Map.size().
        Specified by:
        size in interface java.util.Map

      • isEmpty

        public boolean isEmpty()
        Deprecated.
        Implements Map.isEmpty().
        Specified by:
        isEmpty in interface java.util.Map

      • containsKey

        public boolean containsKey​(java.lang.Object key)
        Deprecated.
        Implements Map.containsKey(Object).
        Specified by:
        containsKey in interface java.util.Map

      • containsValue

        public boolean containsValue​(java.lang.Object value)
        Deprecated.
        Implements Map.containsValue(Object).
        Specified by:
        containsValue in interface java.util.Map

      • get

        public java.lang.Object get​(java.lang.Object o)
        Deprecated.
        Implements Map.get(Object).
        Specified by:
        get in interface java.util.Map

      • getFirst

        public java.util.Map.Entry getFirst()
        Deprecated.
        Return the entry for the "oldest" mapping. That is, return the Map.Entry for the key-value pair that was first put into the map when compared to all the other pairings in the map. This behavior is equivalent to using entrySet().iterator().next(), but this method provides an optimized implementation.
        Returns:
        The first entry in the sequence, or null if the map is empty.

      • getFirstKey

        public java.lang.Object getFirstKey()
        Deprecated.
        Return the key for the "oldest" mapping. That is, return the key for the mapping that was first put into the map when compared to all the other objects in the map. This behavior is equivalent to using getFirst().getKey(), but this method provides a slightly optimized implementation.
        Returns:
        The first key in the sequence, or null if the map is empty.

      • getFirstValue

        public java.lang.Object getFirstValue()
        Deprecated.
        Return the value for the "oldest" mapping. That is, return the value for the mapping that was first put into the map when compared to all the other objects in the map. This behavior is equivalent to using getFirst().getValue(), but this method provides a slightly optimized implementation.
        Returns:
        The first value in the sequence, or null if the map is empty.

      • getLast

        public java.util.Map.Entry getLast()
        Deprecated.
        Return the entry for the "newest" mapping. That is, return the Map.Entry for the key-value pair that was first put into the map when compared to all the other pairings in the map. The behavior is equivalent to: 
            Object obj = null;
    Iterator iter = entrySet().iterator();
    while(iter.hasNext()) {
      obj = iter.next();
    }
    return (Map.Entry)obj;
        However, the implementation of this method ensures an O(1) lookup of the last key rather than O(n).
        Returns:
        The last entry in the sequence, or null if the map is empty.

      • getLastKey

        public java.lang.Object getLastKey()
        Deprecated.
        Return the key for the "newest" mapping. That is, return the key for the mapping that was last put into the map when compared to all the other objects in the map. This behavior is equivalent to using getLast().getKey(), but this method provides a slightly optimized implementation.
        Returns:
        The last key in the sequence, or null if the map is empty.

      • getLastValue

        public java.lang.Object getLastValue()
        Deprecated.
        Return the value for the "newest" mapping. That is, return the value for the mapping that was last put into the map when compared to all the other objects in the map. This behavior is equivalent to using getLast().getValue(), but this method provides a slightly optimized implementation.
        Returns:
        The last value in the sequence, or null if the map is empty.

      • put

        public java.lang.Object put​(java.lang.Object key,
                            java.lang.Object value)
        Deprecated.
        Implements Map.put(Object, Object).
        Specified by:
        put in interface java.util.Map

      • remove

        public java.lang.Object remove​(java.lang.Object key)
        Deprecated.
        Implements Map.remove(Object).
        Specified by:
        remove in interface java.util.Map

      • putAll

        public void putAll​(java.util.Map t)
        Deprecated.
        Adds all the mappings in the specified map to this map, replacing any mappings that already exist (as per Map.putAll(Map)). The order in which the entries are added is determined by the iterator returned from Map.entrySet() for the specified map.
        Specified by:
        putAll in interface java.util.Map
        Parameters:
        t - the mappings that should be added to this map.
        Throws:
        java.lang.NullPointerException - if t is null

      • clear

        public void clear()
        Deprecated.
        Implements Map.clear().
        Specified by:
        clear in interface java.util.Map

      • equals

        public boolean equals​(java.lang.Object obj)
        Deprecated.
        Implements Map.equals(Object).
        Specified by:
        equals in interface java.util.Map
        Overrides:
        equals in class java.lang.Object

      • hashCode

        public int hashCode()
        Deprecated.
        Implements Map.hashCode().
        Specified by:
        hashCode in interface java.util.Map
        Overrides:
        hashCode in class java.lang.Object

      • toString

        public java.lang.String toString()
        Deprecated.
        Provides a string representation of the entries within the map. The format of the returned string may change with different releases, so this method is suitable for debugging purposes only. If a specific format is required, use entrySet().iterator() and iterate over the entries in the map formatting them as appropriate.
        Overrides:
        toString in class java.lang.Object

      • keySet

        public java.util.Set keySet()
        Deprecated.
        Implements Map.keySet().
        Specified by:
        keySet in interface java.util.Map

      • values

        public java.util.Collection values()
        Deprecated.
        Implements Map.values().
        Specified by:
        values in interface java.util.Map

      • entrySet

        public java.util.Set entrySet()
        Deprecated.
        Implements Map.entrySet().
        Specified by:
        entrySet in interface java.util.Map

      • clone

        public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException
        Deprecated.
        Creates a shallow copy of this object, preserving the internal structure by copying only references. The keys and values themselves are not clone()'d. The cloned object maintains the same sequence.
        Returns:
        A clone of this instance.
        Throws:
        java.lang.CloneNotSupportedException - if clone is not supported by a subclass.

      • get

        public java.lang.Object get​(int index)
        Deprecated.
        Gets the key at the specified index.
        Parameters:
        index - the index to retrieve
        Returns:
        the key at the specified index, or null
        Throws:
        java.lang.ArrayIndexOutOfBoundsException - if the index is < 0 or > the size of the map.

      • getValue

        public java.lang.Object getValue​(int index)
        Deprecated.
        Gets the value at the specified index.
        Parameters:
        index - the index to retrieve
        Returns:
        the value at the specified index, or null
        Throws:
        java.lang.ArrayIndexOutOfBoundsException - if the index is < 0 or > the size of the map.

      • indexOf

        public int indexOf​(java.lang.Object key)
        Deprecated.
        Gets the index of the specified key.
        Parameters:
        key - the key to find the index of
        Returns:
        the index, or -1 if not found

      • iterator

        public java.util.Iterator iterator()
        Deprecated.
        Gets an iterator over the keys.
        Returns:
        an iterator over the keys

      • lastIndexOf

        public int lastIndexOf​(java.lang.Object key)
        Deprecated.
        Gets the last index of the specified key.
        Parameters:
        key - the key to find the index of
        Returns:
        the index, or -1 if not found

      • sequence

        public java.util.List sequence()
        Deprecated.
        Returns a List view of the keys rather than a set view. The returned list is unmodifiable. This is required because changes to the values of the list (using ListIterator.set(Object)) will effectively remove the value from the list and reinsert that value at the end of the list, which is an unexpected side effect of changing the value of a list. This occurs because changing the key, changes when the mapping is added to the map and thus where it appears in the list.

        An alternative to this method is to use keySet()

        Returns:
        The ordered list of keys.
        See Also:
        keySet()

      • remove

        public java.lang.Object remove​(int index)
        Deprecated.
        Removes the element at the specified index.
        Parameters:
        index - The index of the object to remove.
        Returns:
        The previous value corresponding the key, or null if none existed.
        Throws:
        java.lang.ArrayIndexOutOfBoundsException - if the index is < 0 or > the size of the map.

      • readExternal

        public void readExternal​(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException
        Deprecated.
        Deserializes this map from the given stream.
        Specified by:
        readExternal in interface java.io.Externalizable
        Parameters:
        in - the stream to deserialize from
        Throws:
        java.io.IOException - if the stream raises it
        java.lang.ClassNotFoundException - if the stream raises it

      • writeExternal

        public void writeExternal​(java.io.ObjectOutput out)
                   throws java.io.IOException
        Deprecated.
        Serializes this map to the given stream.
        Specified by:
        writeExternal in interface java.io.Externalizable
        Parameters:
        out - the stream to serialize to
        Throws:
        java.io.IOException - if the stream raises it