Class HashMap

java.lang.Object
org.exolab.adaptx.util.HashMap
public class HashMap extends Object
My implementation of a JDK 1.2 Map. I do not use synchronization, so be careful in a threaded environment. I also do not specifically "implements" java.util.Map, since support for JDK 1.1 is needed.
Version:
$Revision: 3633 $ $Date: 2003-03-01 08:38:44 +0100 (Sat, 01 Mar 2003) $
Author:
Keith Visco

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    DEFAULT_SIZE
    The default number of buckets in this Map

  • Constructor Summary

    Constructors
    Constructor
    Description
    HashMap()
    Creates a new HashMap with the default number of buckets
    HashMap(int size)
    Creates a new HashMap with the given number of buckets.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    clear()
    Removes all entries from this Map
    boolean
    containsKey(Object key)
    Returns true if the given object is a key contained in this Map
    boolean
    containsValue(Object value)
    Returns true if the given object is a value contained in this Map
    Note: Depending on the size of the Map, this could be a slow operation.
    Iterator
    entries()
    Returns an interator for the entries of this Map.
    boolean
    equals(Object object)
    Returns true if the given Object is a HashMap which contains equivalent HashMap entries as this HashMap.
    Object
    get(Object key)
    Returns the value associated with the given key
    int
    hashCode()
    Returns the hashCode for this Map.
    boolean
    isEmpty()
    Returns true if this map contains no entries
    Iterator
    keys()
     
    void
    put(Object key, Object value)
    Associated the specified value with the given key in this Map
    Object
    remove(Object key)
    Removes the association with the given Key in the Map.
    int
    size()
    Returns the number of associations in the Map

    Methods inherited from class Object

    getClass, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • DEFAULT_SIZE

      public static final int DEFAULT_SIZE
      The default number of buckets in this Map
      See Also:

  • Constructor Details

    • HashMap

      public HashMap()
      Creates a new HashMap with the default number of buckets

    • HashMap

      public HashMap(int size)
      Creates a new HashMap with the given number of buckets.
      Parameters:
      size - , the number of buckets to use, this value must be a non-zero positive integer, if not the default size will be used.
      Note:The number of buckets is not the same as the allocating space for a desired number of entries. If fact, if you know number of entries that will be in the hash, you might want to use a HashMap with a different implementation. This Map is implemented using separate chaining.

  • Method Details

    • clear

      public void clear()
      Removes all entries from this Map

    • containsKey

      public boolean containsKey(Object key)
      Returns true if the given object is a key contained in this Map
      Returns:
      true if the given object is a key contained in this Map

    • containsValue

      public boolean containsValue(Object value)
      Returns true if the given object is a value contained in this Map
      Note: Depending on the size of the Map, this could be a slow operation. If you know the key an object would be associated with, contains key would be much faster, or simply do (get(key) != null).
      Returns:
      true if the given object is a value contained in this Map

    • entries

      public Iterator entries()
      Returns an interator for the entries of this Map. Each element returned by a call to Iterator#next() is a Map.Entry.
      Note: This is different than a JDK 1.2 Map because I didn't want to deal with implementing Sets at this point.
      Returns:
      an Iterator for the entries of this Map.

    • equals

      public boolean equals(Object object)
      Returns true if the given Object is a HashMap which contains equivalent HashMap entries as this HashMap.
      Overrides:
      equals in class Object
      Returns:
      true if the given Object is a HashMap, and is equivalent to this Map
      I will be probably make an interface for Map, to allow comparisons with different Map implemenations.

    • get

      public Object get(Object key)
      Returns the value associated with the given key
      Returns:
      the value associated with the given key

    • hashCode

      public int hashCode()
      Returns the hashCode for this Map. The hash code is the sum of all the hash codes of each entry in the map
      Overrides:
      hashCode in class Object

    • isEmpty

      public boolean isEmpty()
      Returns true if this map contains no entries
      Returns:
      true if this map contains no entries

    • keys

      public Iterator keys()

    • put

      public void put(Object key, Object value)
      Associated the specified value with the given key in this Map
      Parameters:
      key - the object to associate with the given value
      value - the object to add an association in this Map

    • remove

      public Object remove(Object key)
      Removes the association with the given Key in the Map.
      Parameters:
      key - the object key to remove the association for
      Returns:
      the associated value being removed from this Map

    • size

      public int size()
      Returns the number of associations in the Map
      Returns:
      the number of associations in the Map