edu.neu.ccs.quick
Class QuickHashtable

java.lang.Object
  java.util.Dictionary
      java.util.Hashtable
          edu.neu.ccs.quick.QuickHashtable

All Implemented Interfaces:

Cloneable, Map, Serializable

public class QuickHashtable

extends Hashtable

QuickHashtable extends Hashtable by adding one constructor and three methods putPairs, setPairs, and removeKeys that handle an array of Object at once.

In addition, symmetric methods are added that will hash both a key to its value and a value to its key.

All constructors of the original Hashtable class are provided as well.

The only inherited methods that are overridden are those that will throw an exception on null arguments. In this class, such methods will handle null in a sensible fashion.

Since:

2.3

Version:

2.3

See Also:

Serialized Form

Nested Class Summary

Nested classes inherited from class java.util.Hashtable

Field Summary

Fields inherited from class java.util.Hashtable

Constructor Summary

QuickHashtable()
A constructor that delegates to class Hashtable.

QuickHashtable(int initialCapacity)
A constructor that delegates to class Hashtable.

QuickHashtable(int initialCapacity, float loadFactor)
A constructor that delegates to class Hashtable.

QuickHashtable(Map m)
A constructor that delegates to class Hashtable.

QuickHashtable(Object[][] pairs)
Constructor that adds the given 2-dimensional array of key-value pairs one-by-one to the hash table.

Method Summary

boolean	contains(Object value) Returns true if the hash table contains the value.
boolean	containsKey(Object key) Returns true if the hash table contains the key.
boolean	containsValue(Object value) Returns true if the hash table contains the value.
Object	get(Object key) Returns the value to which the hash table maps the specified key.
Object	put(Object key, Object value) Associates the specified value with the specified key in this hash table.
void	putPairs(Object[][] pairs) Method that adds the given 2-dimensional array of key-value pairs one-by-one to the hash table.
void	putPairsSymmetric(Object[][] pairs) Method that adds the given 2-dimensional array of key-value pairs one-by-one symmetrically to the hash table.
void	putSymmetric(Object key, Object value) Method that adds the key-value pair symmetrically to the hash table, that is, the key maps to the value and the value maps to the key.
Object	remove(Object key) Removes the mapping for this key from this hash table if present.
void	removeKeys(Object[] keys) Method that removes the given array of keys one-by-one from the hash table.
void	setPairs(Object[][] pairs) Method that first clears this hash table of any existing pairs and then adds the given array of pairs one-by-one to the hash table.
void	setPairsSymmetric(Object[][] pairs) Method that first clears this hash table of any existing pairs and then adds the given array of pairs one-by-one symmetrically to the hash table.

Methods inherited from class java.util.Hashtable

clear, clone, elements, entrySet, equals, hashCode, isEmpty, keys, keySet, putAll, rehash, size, toString, values

Methods inherited from class java.lang.Object

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

Constructor Detail

QuickHashtable

public QuickHashtable()

A constructor that delegates to class Hashtable.

QuickHashtable

public QuickHashtable(int initialCapacity)

A constructor that delegates to class Hashtable.

QuickHashtable

public QuickHashtable(int initialCapacity,
                      float loadFactor)

A constructor that delegates to class Hashtable.

QuickHashtable

public QuickHashtable(Map m)

A constructor that delegates to class Hashtable.

QuickHashtable

public QuickHashtable(Object[][] pairs)

Constructor that adds the given 2-dimensional array of key-value pairs one-by-one to the hash table.

Ignores key-value pairs in which either item is null.

The capacity is set either to 10 or to 1.5 times the length of the array pairs whichever is larger.

The load factor is set to the default of 0.75.

Parameters:

pairs - the array of pairs to add to this hash table

See Also:

putPairs(Object[][])

Method Detail

put

public Object put(Object key,
                  Object value)

Associates the specified value with the specified key in this hash table. If the hash table previously contained a mapping for this key, the old value is replaced.

If the key or value is null, then simply returns null.

Parameters:

key - the key associated with the specified value

value - the value to be associated with the specified key

Returns:

previous value associated with specified key, or null if there was no mapping for key

See Also:

Hashtable.put(Object, Object)

get

public Object get(Object key)

Returns the value to which the hash table maps the specified key. Returns null if the hash table contains no mapping for the key.

If the key is null, then simply returns null.

Parameters:

key - the key whose associated value is to be returned

Returns:

the value to which the hash table maps the specified key, or null if the hash table contains no mapping for the key

See Also:

Hashtable.get(Object)

remove

public Object remove(Object key)

Removes the mapping for this key from this hash table if present.

If the key is null, then simply returns null.

Parameters:

key - the key whose mapping should be removed

Returns:

previous value associated with specified key, or null if there was no mapping for key

See Also:

Hashtable.remove(Object)

containsKey

public boolean containsKey(Object key)

Returns true if the hash table contains the key.

If the key is null, then simply returns false.

Parameters:

key - the key whose presence in the hash table is to be tested

Returns:

true if the key is non-null and is a key in the hash table

See Also:

Hashtable.containsKey(Object)

containsValue

public boolean containsValue(Object value)

Returns true if the hash table contains the value.

If the value is null, then simply returns false.

Parameters:

value - the value whose presence in the hash table is to be tested

Returns:

true if the value is non-null and is a value in the hash table

See Also:

Hashtable.containsValue(Object)

contains

public boolean contains(Object value)

Returns true if the hash table contains the value.

If the value is null, then simply returns false.

Parameters:

value - the value whose presence in the hash table is to be tested

Returns:

true if the value is non-null and is a value in the hash table

See Also:

Hashtable.contains(Object)

putPairs

public void putPairs(Object[][] pairs)

Method that adds the given 2-dimensional array of key-value pairs one-by-one to the hash table.

If pairs is null, then does nothing.

Ignores any subarray pairs[i] that is null or not of length 2.

Ignores key-value pairs in which either item is null.

Parameters:

pairs - the array of pairs to add to this hash table

See Also:

QuickHashtable(Object[][]), setPairs(Object[][]), removeKeys(Object[]), putSymmetric(Object, Object), putPairsSymmetric(Object[][]), setPairsSymmetric(Object[][])

setPairs

public void setPairs(Object[][] pairs)

Method that first clears this hash table of any existing pairs and then adds the given array of pairs one-by-one to the hash table.

If pairs is null, then this method is equivalent to the inherited method clear.

Ignores any subarray pairs[i] that is null or not of length 2.

Ignores key-value pairs in which either item is null.

Parameters:

pairs - the array of pairs to add to this hash table after clearance

See Also:

putPairs(Object[][]), removeKeys(Object[]), putSymmetric(Object, Object), putPairsSymmetric(Object[][]), setPairsSymmetric(Object[][])

removeKeys

public void removeKeys(Object[] keys)

Method that removes the given array of keys one-by-one from the hash table.

If keys is null, then does nothing.

Ignores key items that are null.

Parameters:

keys - the array of keys to remove from this hash table

See Also:

putPairs(Object[][]), setPairs(Object[][]), putSymmetric(Object, Object), putPairsSymmetric(Object[][]), setPairsSymmetric(Object[][])

putSymmetric

public void putSymmetric(Object key,
                         Object value)

Method that adds the key-value pair symmetrically to the hash table, that is, the key maps to the value and the value maps to the key.

Does nothing if the key or value is null.

Parameters:

key - the key in the key-value pair

value - the value in the key-value pair

See Also:

putPairs(Object[][]), setPairs(Object[][]), removeKeys(Object[]), putPairsSymmetric(Object[][]), setPairsSymmetric(Object[][])

putPairsSymmetric

public void putPairsSymmetric(Object[][] pairs)

Method that adds the given 2-dimensional array of key-value pairs one-by-one symmetrically to the hash table.

If pairs is null, then does nothing.

Ignores any subarray pairs[i] that is null or not of length 2.

Ignores key-value pairs in which either item is null.

Parameters:

pairs - the array of pairs to add symmetrically to this hash table

See Also:

putPairs(Object[][]), setPairs(Object[][]), removeKeys(Object[]), putSymmetric(Object, Object), setPairsSymmetric(Object[][])

setPairsSymmetric

public void setPairsSymmetric(Object[][] pairs)

Method that first clears this hash table of any existing pairs and then adds the given array of pairs one-by-one symmetrically to the hash table.

If pairs is null, then this method is equivalent to the inherited method clear.

Ignores any subarray pairs[i] that is null or not of length 2.

Ignores key-value pairs in which either item is null.

Parameters:

pairs - the array of pairs to add symmetrically to this hash table after clearance

See Also:

putPairs(Object[][]), setPairs(Object[][]), removeKeys(Object[]), putSymmetric(Object, Object), putPairsSymmetric(Object[][])