edu.berkeley.guir.lib.awt.image
Class IntHashtable

java.lang.Object
  |
  +--java.util.Dictionary
        |
        +--edu.berkeley.guir.lib.awt.image.IntHashtable

All Implemented Interfaces:

Cloneable

public class IntHashtable

extends Dictionary

implements Cloneable

A Hashtable that uses ints as the keys.

Use just like java.util.Hashtable, except that the keys must be ints. This is much faster than creating a new Integer for each access.

Fetch the software.
Fetch the entire Acme package.

See Also:

Hashtable

Constructor Summary

IntHashtable()
Constructs a new, empty hashtable.

IntHashtable(int initialCapacity)
Constructs a new, empty hashtable with the specified initial capacity.

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

Method Summary

void	clear() Clears the hash table so that it has no more elements in it.
Object	clone() Creates a clone of the hashtable.
boolean	contains(Object value) Returns true if the specified object is an element of the hashtable.
boolean	containsKey(int key) Returns true if the collection contains an element for the key.
Enumeration	elements() Returns an enumeration of the elements.
Object	get(int key) Gets the object associated with the specified key in the hashtable.
Object	get(Object okey) A get method that takes an Object, for compatibility with java.util.Dictionary.
boolean	isEmpty() Returns true if the hashtable contains no elements.
Enumeration	keys() Returns an enumeration of the hashtable's keys.
Object	put(int key, Object value) Puts the specified element into the hashtable, using the specified key.
Object	put(Object okey, Object value) A put method that takes an Object, for compatibility with java.util.Dictionary.
protected void	rehash() Rehashes the content of the table into a bigger table.
Object	remove(int key) Removes the element corresponding to the key.
Object	remove(Object okey) A remove method that takes an Object, for compatibility with java.util.Dictionary.
int	size() Returns the number of elements contained in the hashtable.
String	toString() Converts to a rather lengthy String.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

IntHashtable

public IntHashtable(int initialCapacity,
                    float loadFactor)

Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.

Parameters:

initialCapacity - the initial number of buckets

loadFactor - a number between 0.0 and 1.0, it defines the threshold for rehashing the hashtable into a bigger one.

Throws:

IllegalArgumentException - If the initial capacity is less than or equal to zero.

IllegalArgumentException - If the load factor is less than or equal to zero.

IntHashtable

public IntHashtable(int initialCapacity)

Constructs a new, empty hashtable with the specified initial capacity.

Parameters:

initialCapacity - the initial number of buckets

IntHashtable

public IntHashtable()

Constructs a new, empty hashtable. A default capacity and load factor is used. Note that the hashtable will automatically grow when it gets full.

Method Detail

size

public int size()

Returns the number of elements contained in the hashtable.

Overrides:

size in class Dictionary

isEmpty

public boolean isEmpty()

Returns true if the hashtable contains no elements.

Overrides:

isEmpty in class Dictionary

keys

public Enumeration keys()

Returns an enumeration of the hashtable's keys.

Overrides:

keys in class Dictionary

See Also:

elements()

elements

public Enumeration elements()

Returns an enumeration of the elements. Use the Enumeration methods on the returned object to fetch the elements sequentially.

Overrides:

elements in class Dictionary

See Also:

keys()

contains

public boolean contains(Object value)

Returns true if the specified object is an element of the hashtable. This operation is more expensive than the containsKey() method.

Parameters:

value - the value that we are looking for

Throws:

NullPointerException - If the value being searched for is equal to null.

See Also:

containsKey(int)

containsKey

public boolean containsKey(int key)

Returns true if the collection contains an element for the key.

Parameters:

key - the key that we are looking for

See Also:

contains(java.lang.Object)

get

public Object get(int key)

Gets the object associated with the specified key in the hashtable.

Parameters:

key - the specified key

See Also:

put(int, java.lang.Object)

get

public Object get(Object okey)

A get method that takes an Object, for compatibility with java.util.Dictionary. The Object must be an Integer.

Overrides:

get in class Dictionary

rehash

protected void rehash()

Rehashes the content of the table into a bigger table. This method is called automatically when the hashtable's size exceeds the threshold.

put

public Object put(int key,
                  Object value)

Puts the specified element into the hashtable, using the specified key. The element may be retrieved by doing a get() with the same key. The key and the element cannot be null.

Parameters:

key - the specified key in the hashtable

value - the specified element

Returns:

the old value of the key, or null if it did not have one.

Throws:

NullPointerException - If the value of the element is equal to null.

See Also:

get(int)

put

public Object put(Object okey,
                  Object value)

A put method that takes an Object, for compatibility with java.util.Dictionary. The Object must be an Integer.

Overrides:

put in class Dictionary

remove

public Object remove(int key)

Removes the element corresponding to the key. Does nothing if the key is not present.

Parameters:

key - the key that needs to be removed

Returns:

the value of key, or null if the key was not found.

remove

public Object remove(Object okey)

A remove method that takes an Object, for compatibility with java.util.Dictionary. The Object must be an Integer.

Overrides:

remove in class Dictionary

clear

public void clear()

Clears the hash table so that it has no more elements in it.

clone

public Object clone()

Creates a clone of the hashtable. A shallow copy is made, the keys and elements themselves are NOT cloned. This is a relatively expensive operation.

Overrides:

clone in class Object

toString

public String toString()

Converts to a rather lengthy String.

Overrides:

toString in class Object