Class Hashtable


  • public class Hashtable
    extends java.lang.Object
    The main hash-table implementation
    • Constructor Summary

      Constructors 
      Constructor Description
      Hashtable()
      Constructs a new, empty hashtable with a default capacity and load factor.
      Hashtable​(int initialCapacity)
      Constructs a new, empty hashtable with the specified initial capacity and default load factor.
      Hashtable​(int initialCapacity, float loadFactor)
      Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Clears this hashtable so that it contains no keys.
      boolean contains​(java.lang.Object value)
      Tests if some key maps into the specified value in this hashtable.
      boolean containsKey​(java.lang.Object key)
      Tests if the specified object is a key in this hashtable.
      java.util.Enumeration elements()
      Returns an enumeration of the values in this hashtable.
      java.lang.Object get​(java.lang.Object key)
      Returns the value to which the specified key is mapped in this hashtable.
      boolean isEmpty()
      Tests if this hashtable maps no keys to values.
      java.util.Enumeration keys()
      Returns an enumeration of the keys in this hashtable.
      java.lang.Object put​(java.lang.Object key, java.lang.Object value)
      Maps the specified key to the specified value in this hashtable.
      java.lang.Object remove​(java.lang.Object key)
      Removes the key (and its corresponding value) from this hashtable.
      int size()
      Returns the number of keys in this hashtable.
      java.lang.String toString()
      Returns a rather long string representation of this hashtable.
      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Constructor Detail

      • Hashtable

        public Hashtable​(int initialCapacity,
                         float loadFactor)
        Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.
      • Hashtable

        public Hashtable​(int initialCapacity)
        Constructs a new, empty hashtable with the specified initial capacity and default load factor.
      • Hashtable

        public Hashtable()
        Constructs a new, empty hashtable with a default capacity and load factor.
    • Method Detail

      • size

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

        public boolean isEmpty()
        Tests if this hashtable maps no keys to values.
      • keys

        public java.util.Enumeration keys()
        Returns an enumeration of the keys in this hashtable.
      • elements

        public java.util.Enumeration elements()
        Returns an enumeration of the values in this hashtable. Use the Enumeration methods on the returned object to fetch the elements sequentially.
      • contains

        public boolean contains​(java.lang.Object value)
        Tests if some key maps into the specified value in this hashtable. This operation is more expensive than the containsKey method.
      • containsKey

        public boolean containsKey​(java.lang.Object key)
        Tests if the specified object is a key in this hashtable.
      • get

        public java.lang.Object get​(java.lang.Object key)
        Returns the value to which the specified key is mapped in this hashtable.
      • put

        public java.lang.Object put​(java.lang.Object key,
                                    java.lang.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.

      • remove

        public java.lang.Object remove​(java.lang.Object key)
        Removes the key (and its corresponding value) from this hashtable. This method does nothing if the key is not in the hashtable.
      • clear

        public void clear()
        Clears this hashtable so that it contains no keys.
      • toString

        public java.lang.String toString()
        Returns a rather long string representation of this hashtable. Handy for debugging - leave it here!!!
        Overrides:
        toString in class java.lang.Object