Class SimpleHashtable

java.lang.Object
com.sun.xml.dtdparser.SimpleHashtable
All Implemented Interfaces:
Enumeration

final class SimpleHashtable extends Object implements Enumeration
This class implements a special purpose hashtable. It works like a normal java.util.Hashtable except that:

  1. Keys to "get" are strings which are known to be interned, so that "==" is used instead of "String.equals". (Interning could be document-relative instead of global.)

  2. It's not synchronized, since it's to be used only by one thread at a time.

  3. The keys () enumerator allocates no memory, with live updates to the data disallowed.

  4. It's got fewer bells and whistles: fixed threshold and load factor, no JDK 1.2 collection support, only keys can be enumerated, things can't be removed, simpler inheritance; more.

The overall result is that it's less expensive to use these in performance-critical locations, in terms both of CPU and memory, than java.util.Hashtable instances. In this package it makes a significant difference when normalizing attributes, which is done for each start-element construct.

Version:
$Revision: 1.2 $
  • Field Details

  • Constructor Details

    • SimpleHashtable

      public SimpleHashtable(int initialCapacity)
      Constructs a new, empty hashtable with the specified initial capacity.
      Parameters:
      initialCapacity - the initial capacity of the hashtable.
    • SimpleHashtable

      public SimpleHashtable()
      Constructs a new, empty hashtable with a default capacity.
  • Method Details

    • clear

      public void clear()
    • size

      public int size()
      Returns the number of keys in this hashtable.
      Returns:
      the number of keys in this hashtable.
    • keys

      public Enumeration keys()
      Returns an enumeration of the keys in this hashtable.
      Returns:
      an enumeration of the keys in this hashtable.
      See Also:
    • hasMoreElements

      public boolean hasMoreElements()
      Used to view this as an enumeration; returns true if there are more keys to be enumerated.
      Specified by:
      hasMoreElements in interface Enumeration
    • nextElement

      public Object nextElement()
      Used to view this as an enumeration; returns the next key in the enumeration.
      Specified by:
      nextElement in interface Enumeration
    • get

      public Object get(String key)
      Returns the value to which the specified key is mapped in this hashtable.
    • getNonInterned

      public Object getNonInterned(String key)
      Returns the value to which the specified key is mapped in this hashtable ... the key isn't necessarily interned, though.
    • rehash

      private void rehash()
      Increases the capacity of and internally reorganizes this hashtable, in order to accommodate and access its entries more efficiently. This method is called automatically when the number of keys in the hashtable exceeds this hashtable's capacity and load factor.
    • put

      public Object put(Object key, Object value)
      Maps the specified key to the specified value in this hashtable. Neither the key nor the value can be null.

      The value can be retrieved by calling the get method with a key that is equal to the original key.