javolution.util

Class Index

java.lang.Object

java.lang.Number

javolution.util.Index

All Implemented Interfaces:

Serializable, Comparable<Index>, Immutable<Index>, ValueType<Index>

@Realtime
@DefaultTextFormat(value=Index.Decimal.class)
public final class Index
extends Number
implements Comparable<Index>, ValueType<Index>

A non-negative number representing a position in an arrangement. For example:

 class SparseVector<F> {
     FastMap<Index, F> elements = new FastMap<Index, F>();
     ...
 }

Index performance is on-par with the primitive int type for small values and similar to Integer instances for large values. Small indexes have no adverse effect on the garbage collector and have fast equals method due to their unicity.

Version:

5.1, July 26, 2007

Author:

Jean-Marie Dautelle

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Index.Decimal Default text format for indices (decimal value representation).

Field Summary

Fields

Modifier and Type	Field and Description
static Configurable<Integer>	UNIQUE Holds the number of unique preallocated instances (default 1024).
static Index	ZERO Holds the index zero (value 0).

Method Summary

Methods

Modifier and Type	Method and Description
int	compareTo(Index that) Compares this index with the specified index for order.
int	compareTo(int value) Compares this index with the specified integer value for order.
Index	copy() Returns a copy of this index or this if the indexes is small (in permanent memory) in order to maintain unicity.
double	doubleValue() Returns the index value as double.
boolean	equals(Object obj) Indicates if this index is equals to the one specified (for small indices this method is equivalent to ==).
float	floatValue() Returns the index value as float.
int	hashCode() Returns the hash code for this index.
int	intValue() Returns the index value as int.
boolean	isZero() Indicates if this index is zero.
long	longValue() Returns the index value as long.
Index	next() Returns the index after this one.
Index	previous() Returns the index before this one.
protected Object	readResolve() Ensures index unicity during deserialization.
String	toString() Returns the String representation of this index.
Index	value() Returns this.
static Index	valueOf(int value) Returns the index for the specified int non-negative value (returns a preallocated instance if the specified value is small).

Methods inherited from class java.lang.Number

byteValue, shortValue

Methods inherited from class java.lang.Object

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

Field Detail

UNIQUE

public static final Configurable<Integer> UNIQUE

Holds the number of unique preallocated instances (default 1024). This number is configurable, for example with -Djavolution.util.Index#UNIQUE=0 there is no unique instance.

ZERO

public static final Index ZERO

Holds the index zero (value 0).

Method Detail

valueOf

public static Index valueOf(int value)

Returns the index for the specified int non-negative value (returns a preallocated instance if the specified value is small).

Parameters:

value - the index value.

Returns:

the corresponding index.

Throws:

IndexOutOfBoundsException - if value < 0

compareTo

public int compareTo(Index that)

Compares this index with the specified index for order. Returns a negative integer, zero, or a positive integer as this index is less than, equal to, or greater than the specified index.

Specified by:

compareTo in interface Comparable<Index>

Parameters:

that - the index to be compared.

Returns:

a negative integer, zero, or a positive integer as this index is less than, equal to, or greater than the specified index.

compareTo

public int compareTo(int value)

Compares this index with the specified integer value for order. Returns a negative integer, zero, or a positive integer as this index is less than, equal to, or greater than the specified value.

Parameters:

value - the value to be compared.

Returns:

a negative integer, zero, or a positive integer as this index is less than, equal to, or greater than the specified value.

copy

public Index copy()

Returns a copy of this index or this if the indexes is small (in permanent memory) in order to maintain unicity.

doubleValue

public double doubleValue()

Returns the index value as double.

Specified by:

doubleValue in class Number

Returns:

the index value.

equals

public boolean equals(Object obj)

Indicates if this index is equals to the one specified (for small indices this method is equivalent to ==).

Overrides:

equals in class Object

floatValue

public float floatValue()

Returns the index value as float.

Specified by:

floatValue in class Number

Returns:

the index value.

hashCode

public int hashCode()

Returns the hash code for this index.

Overrides:

hashCode in class Object

intValue

public int intValue()

Returns the index value as int.

Specified by:

intValue in class Number

Returns:

the index value.

isZero

public boolean isZero()

Indicates if this index is zero.

Returns:

this == ZERO

longValue

public long longValue()

Returns the index value as long.

Specified by:

longValue in class Number

Returns:

the index value.

next

public Index next()

Returns the index after this one.

previous

public Index previous()

Returns the index before this one.

Throws:

IndexOutOfBoundsException - if (this == Index.ZERO)

readResolve

protected final Object readResolve()
                            throws ObjectStreamException

Ensures index unicity during deserialization.

Throws:

ObjectStreamException

toString

public String toString()

Returns the String representation of this index.

Overrides:

toString in class Object

Returns:

TextContext.getFormat(Index.class).format(this)

value

public Index value()

Description copied from interface: ValueType

Returns this.

Specified by:

value in interface Immutable<Index>

Specified by:

value in interface ValueType<Index>