gnu.trove

Class TObjectHash

java.lang.Object

gnu.trove.THash

gnu.trove.TObjectHash

All Implemented Interfaces:

TObjectHashingStrategy, java.io.Serializable, java.lang.Cloneable

Direct Known Subclasses:

THashMap, THashSet, TObjectDoubleHashMap, TObjectFloatHashMap, TObjectIntHashMap, TObjectLongHashMap

public abstract class TObjectHash
extends THash
implements java.io.Serializable, TObjectHashingStrategy

An open addressed hashing implementation for Object types. Created: Sun Nov 4 08:56:06 2001

Version:

$Id: TObjectHash.java,v 1.15 2003/03/23 04:06:59 ericdf Exp $

Author:

Eric D. Friedman

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected TObjectHashingStrategy	_hashingStrategy the strategy used to hash objects in this collection.
protected java.lang.Object[]	_set the set of Objects
protected static java.lang.Object	REMOVED

Fields inherited from class gnu.trove.THash

_free, _loadFactor, _maxSize, _size, DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR

Constructor Summary

Constructors

Constructor and Description
TObjectHash() Creates a new TObjectHash instance with the default capacity and load factor.
TObjectHash(int initialCapacity) Creates a new TObjectHash instance whose capacity is the next highest prime above initialCapacity + 1 unless that value is already prime.
TObjectHash(int initialCapacity, float loadFactor) Creates a new TObjectHash instance with a prime value at or near the specified capacity and load factor.
TObjectHash(int initialCapacity, float loadFactor, TObjectHashingStrategy strategy) Creates a new TObjectHash instance with a prime value at or near the specified capacity and load factor.
TObjectHash(int initialCapacity, TObjectHashingStrategy strategy) Creates a new TObjectHash instance whose capacity is the next highest prime above initialCapacity + 1 unless that value is already prime.
TObjectHash(TObjectHashingStrategy strategy) Creates a new TObjectHash instance with the default capacity and load factor and a custom hashing strategy.

Method Summary

Methods

Modifier and Type	Method and Description
protected int	capacity()
java.lang.Object	clone()
int	computeHashCode(java.lang.Object o) This is the default implementation of TObjectHashingStrategy: it delegates hashing to the Object's hashCode method.
boolean	contains(java.lang.Object obj) Searches the set for obj
boolean	equals(java.lang.Object o1, java.lang.Object o2) This is the default implementation of TObjectHashingStrategy: it delegates equality comparisons to the first parameter's equals() method.
boolean	forEach(TObjectProcedure procedure) Executes procedure for each element in the set.
protected int	index(java.lang.Object obj) Locates the index of obj.
protected int	insertionIndex(java.lang.Object obj) Locates the index at which obj can be inserted.
protected void	removeAt(int index) Delete the record at index.
protected int	setUp(int initialCapacity) initializes the Object set of this hash table.
protected void	throwObjectContractViolation(java.lang.Object o1, java.lang.Object o2) Convenience methods for subclasses to use in throwing exceptions about badly behaved user objects employed as keys.

Methods inherited from class gnu.trove.THash

clear, compact, ensureCapacity, isEmpty, postInsertHook, rehash, size, trimToSize

Methods inherited from class java.lang.Object

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

Field Detail

_set

protected transient java.lang.Object[] _set

the set of Objects

_hashingStrategy

protected TObjectHashingStrategy _hashingStrategy

the strategy used to hash objects in this collection.

REMOVED

protected static final java.lang.Object REMOVED

Constructor Detail

TObjectHash

public TObjectHash()

Creates a new TObjectHash instance with the default capacity and load factor.

TObjectHash

public TObjectHash(TObjectHashingStrategy strategy)

Creates a new TObjectHash instance with the default capacity and load factor and a custom hashing strategy.

Parameters:

strategy - used to compute hash codes and to compare objects.

TObjectHash

public TObjectHash(int initialCapacity)

Creates a new TObjectHash instance whose capacity is the next highest prime above initialCapacity + 1 unless that value is already prime.

Parameters:

initialCapacity - an int value

TObjectHash

public TObjectHash(int initialCapacity,
           TObjectHashingStrategy strategy)

Creates a new TObjectHash instance whose capacity is the next highest prime above initialCapacity + 1 unless that value is already prime. Uses the specified custom hashing strategy.

Parameters:

initialCapacity - an int value

strategy - used to compute hash codes and to compare objects.

TObjectHash

public TObjectHash(int initialCapacity,
           float loadFactor)

Creates a new TObjectHash instance with a prime value at or near the specified capacity and load factor.

Parameters:

initialCapacity - used to find a prime capacity for the table.

loadFactor - used to calculate the threshold over which rehashing takes place.

TObjectHash

public TObjectHash(int initialCapacity,
           float loadFactor,
           TObjectHashingStrategy strategy)

Creates a new TObjectHash instance with a prime value at or near the specified capacity and load factor. Uses the specified custom hashing strategy.

Parameters:

initialCapacity - used to find a prime capacity for the table.

loadFactor - used to calculate the threshold over which rehashing takes place.

strategy - used to compute hash codes and to compare objects.

Method Detail

clone

public java.lang.Object clone()

Overrides:

clone in class THash

Returns:

a shallow clone of this collection

capacity

protected int capacity()

Specified by:

capacity in class THash

Returns:

the current physical capacity of the hash table.

removeAt

protected void removeAt(int index)

Description copied from class: THash

Delete the record at index. Reduces the size of the collection by one.

Overrides:

removeAt in class THash

Parameters:

index - an int value

setUp

protected int setUp(int initialCapacity)

initializes the Object set of this hash table.

Overrides:

setUp in class THash

Parameters:

initialCapacity - an int value

Returns:

an int value

forEach

public boolean forEach(TObjectProcedure procedure)

Executes procedure for each element in the set.

Parameters:

procedure - a TObjectProcedure value

Returns:

false if the loop over the set terminated because the procedure returned false for some value.

contains

public boolean contains(java.lang.Object obj)

Searches the set for obj

Parameters:

obj - an Object value

Returns:

a boolean value

index

protected int index(java.lang.Object obj)

Locates the index of obj.

Parameters:

obj - an Object value

Returns:

the index of obj or -1 if it isn't in the set.

insertionIndex

protected int insertionIndex(java.lang.Object obj)

Locates the index at which obj can be inserted. if there is already a value equal()ing obj in the set, returns that value's index as -index - 1.

Parameters:

obj - an Object value

Returns:

the index of a FREE slot at which obj can be inserted or, if obj is already stored in the hash, the negative value of that index, minus 1: -index -1.

computeHashCode

public final int computeHashCode(java.lang.Object o)

This is the default implementation of TObjectHashingStrategy: it delegates hashing to the Object's hashCode method.

Specified by:

computeHashCode in interface TObjectHashingStrategy

Parameters:

object - for which the hashcode is to be computed

Returns:

the hashCode

See Also:

Object.hashCode()

equals

public final boolean equals(java.lang.Object o1,
             java.lang.Object o2)

This is the default implementation of TObjectHashingStrategy: it delegates equality comparisons to the first parameter's equals() method.

Specified by:

equals in interface TObjectHashingStrategy

Parameters:

o1 - an Object value

o2 - an Object value

Returns:

true if the objects are equal

See Also:

Object.equals(Object)

throwObjectContractViolation

protected final void throwObjectContractViolation(java.lang.Object o1,
                                java.lang.Object o2)
                                           throws java.lang.IllegalArgumentException

Convenience methods for subclasses to use in throwing exceptions about badly behaved user objects employed as keys. We have to throw an IllegalArgumentException with a rather verbose message telling the user that they need to fix their object implementation to conform to the general contract for java.lang.Object.

Parameters:

o1 - the first of the equal elements with unequal hash codes.

o2 - the second of the equal elements with unequal hash codes.

Throws:

java.lang.IllegalArgumentException - the whole point of this method.