BucketizedHashtable (utility module for cmp 4.0 API)

java.lang.Object
- com.sun.jdo.spi.persistence.utility.BucketizedHashtable

All Implemented Interfaces:

Serializable, Cloneable, Map
```
public class BucketizedHashtable
extends Object
implements Cloneable, Map, Serializable
```
This class implements bucketize hashtable, which subdivide the key collection stored into several hashtables (buckets) of smaller size. This will reduce the contention of hashtable.

Author:

Shing Wai Chan

See Also:
Serialized Form

Nested Class Summary
- Nested classes/interfaces inherited from interface java.util.Map
  Map.Entry<K,V>

Constructor Summary

Constructors
Constructor and Description
`BucketizedHashtable()` Constructs a new, empty BucketizedHashtable with the default bucket size 11, default initial capacity (11 * bucketSize) and default load factor 0.75.
`BucketizedHashtable(int bucketSize)` Constructs a new, empty BucketizedHashtable with the specified bucket size, default initial capacity (11 * bucketSize) and default load factor 0.75.
`BucketizedHashtable(int bucketSize, int initialCapacity)` Constructs a new, empty BucketizedHashtable with the specified bucket size, initial capacity and default load factor 0.75.
`BucketizedHashtable(int bucketSize, int initialCapacity, float loadFactor)` Constructs a new, empty BucketizedHashtable with the specified bucket size, initial capacity and load factor.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`clear()` Clears this BucketizedHashtable so that it contains no key.
`Object`	`clone()` Creates and returns a shallow copy of this object.
`boolean`	`containsKey(Object key)`
`boolean`	`containsValue(Object value)`
`Set`	`entrySet()` The return set is backed by the map, so changes to the map are reflected in the set, and vice-versa.
`boolean`	`equals(Object o)` Compares the specified object with this map for equality.
`Object`	`get(Object key)`
`int`	`hashCode()`
`boolean`	`isEmpty()`
`Set`	`keySet()` The return set is backed by the map, so changes to the map are reflected in the set, and vice-versa.
`Object`	`put(Object key, Object value)` Maps the specified `key` to the specified `value` in this hashtable.
`void`	`putAll(Map t)`
`Object`	`remove(Object key)` Remove the key and its corresponding value.
`int`	`size()`
`String`	`toString()`
`Collection`	`values()` The return collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa.

Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - BucketizedHashtable
```
public BucketizedHashtable(int bucketSize,
                   int initialCapacity,
                   float loadFactor)
```
    Constructs a new, empty BucketizedHashtable with the specified bucket size, initial capacity and load factor.
    
    Parameters:
    bucketSize - the number of buckets used for hashing
    initialCapacity - the initial capacity of BucketizedHashtable
    loadFactor - the load factor of hashtable
  - BucketizedHashtable
```
public BucketizedHashtable(int bucketSize,
                   int initialCapacity)
```
    Constructs a new, empty BucketizedHashtable with the specified bucket size, initial capacity and default load factor 0.75.
    
    Parameters:
    bucketSize - the number of buckets used for hashing
    initialCapacity - the initial capacity of hashtable
  - BucketizedHashtable
```
public BucketizedHashtable(int bucketSize)
```
    Constructs a new, empty BucketizedHashtable with the specified bucket size, default initial capacity (11 * bucketSize) and default load factor 0.75.
    
    Parameters:
    bucketSize - the number of buckets used for hashing
  - BucketizedHashtable
```
public BucketizedHashtable()
```
    Constructs a new, empty BucketizedHashtable with the default bucket size 11, default initial capacity (11 * bucketSize) and default load factor 0.75.
- Method Detail
  - get
```
public Object get(Object key)
```
    Specified by:
    
    get in interface Map
    
    Parameters:
    key - a key in the hashtable
    
    Returns:
    the value to which the specified key is mapped.
  - remove
```
public Object remove(Object key)
```
    Remove the key and its corresponding value.
    
    Specified by:
    
    remove in interface Map
    
    Parameters:
    key - the key that needs to be removed
    
    Returns:
    the value to which the key had been mapped, or null if the key did not have a mapping.
  - 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.
    
    Specified by:
    
    put in interface Map
    
    Parameters:
    key - the hashtable key
    value - the value
    
    Returns:
    the previous value of the specified key in hashtables, or null if it did not have one.
  - putAll
```
public void putAll(Map t)
```
    Specified by:
    
    putAll in interface Map
    
    Parameters:
    t - BucketizedHashtable or a Map with a supported operation entrySet
  - containsKey
```
public boolean containsKey(Object key)
```
    Specified by:
    
    containsKey in interface Map
    
    Parameters:
    key - possible key
    
    Returns:
    true if and only if the specified object is a key in one of of the hashtables
  - containsValue
```
public boolean containsValue(Object value)
```
    Specified by:
    
    containsValue in interface Map
    
    Parameters:
    value - possible value
    
    Returns:
    true if and only if the specified object is a value in one of of the hashtables
  - size
```
public int size()
```
    Specified by:
    
    size in interface Map
    
    Returns:
    the total number of key-value mappings of all buckets
  - hashCode
```
public int hashCode()
```
    Specified by:
    
    hashCode in interface Map
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    the hash code value for this map
  - isEmpty
```
public boolean isEmpty()
```
    Specified by:
    
    isEmpty in interface Map
    
    Returns:
    true if this map contains no key-value mappings
  - clear
```
public void clear()
```
    Clears this BucketizedHashtable so that it contains no key.
    
    Specified by:
    
    clear in interface Map
  - entrySet
```
public Set entrySet()
```
    The return set is backed by the map, so changes to the map are reflected in the set, and vice-versa.
    
    Specified by:
    
    entrySet in interface Map
    
    Returns:
    a set of Map.Entry when bucketSet equal 1
    
    Throws:
    
    UnsupportedOperationException - when bucketSize is greater one
  - keySet
```
public Set keySet()
```
    The return set is backed by the map, so changes to the map are reflected in the set, and vice-versa.
    
    Specified by:
    
    keySet in interface Map
    
    Returns:
    a set of keys when bucketSet equal 1
    
    Throws:
    
    UnsupportedOperationException - when bucketSize is greater one
  - values
```
public Collection values()
```
    The return collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa.
    
    Specified by:
    
    values in interface Map
    
    Returns:
    a collection of values when bucketSet equal 1
    
    Throws:
    
    UnsupportedOperationException - when bucketSize is greater one
  - equals
```
public boolean equals(Object o)
```
    Compares the specified object with this map for equality.
    
    Specified by:
    
    equals in interface Map
    
    Overrides:
    
    equals in class Object
    
    Returns:
    true if the specified object is a BucketizedHashtable with hashtables represent the same set of mappings.
  - clone
```
public Object clone()
```
    Creates and returns a shallow copy of this object. The keys and values are not cloned.
    
    Overrides:
    
    clone in class Object
    
    Returns:
    a clone of BucketizedHashtable
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
    
    Returns:
    a string representation of this BucketizedHashtable

Class BucketizedHashtable

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

BucketizedHashtable

BucketizedHashtable

BucketizedHashtable

BucketizedHashtable

Method Detail

get

remove

put

putAll

containsKey

containsValue

size

hashCode

isEmpty

clear

entrySet

keySet

values

equals

clone

toString