Package org.openstreetmap.josm.tools

Class AlphanumComparator

java.lang.Object

org.openstreetmap.josm.tools.AlphanumComparator

All Implemented Interfaces:

java.io.Serializable, java.util.Comparator<java.lang.String>

public final class AlphanumComparator
extends java.lang.Object
implements java.util.Comparator<java.lang.String>, java.io.Serializable

The Alphanum Algorithm is an improved sorting algorithm for strings containing numbers: Instead of sorting numbers in ASCII order like a standard sort, this algorithm sorts numbers in numeric order.

The Alphanum Algorithm is discussed at DaveKoelle.com

This is an updated version with enhancements made by Daniel Migowski, Andre Bogus, David Koelle and others.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
private static byte[]	ASCII_MAPPING	A mapping from ASCII characters to the default Collator order.
(package private) static java.lang.String	ASCII_SORT_ORDER	The sort order for the fast ASCII sort method.
private static AlphanumComparator	INSTANCE
private static long	serialVersionUID
(package private) static boolean	useFastASCIISort	true to use the faster ASCII sorting algorithm.

Constructor Summary

Constructors

Modifier	Constructor	Description
private	AlphanumComparator()	Constructs a new Alphanum Comparator.

Method Summary

Modifier and Type	Method	Description
int	compare(java.lang.String s1, java.lang.String s2)
private static int	compareChunk(java.lang.String thisChunk, int thisChunkLength, java.lang.String thatChunk, int thatChunkLength)	Compare two string chunks
private static int	compareString(java.lang.String string1, int len1, java.lang.String string2, int len2)	Compare two ASCII strings in a manner compatible with the default Collator
private static java.lang.String	getChunk(java.lang.String s, int slength, int marker)	Returns an alphanum chunk.
static AlphanumComparator	getInstance()	Replies the unique instance.
private static boolean	isAscii(java.lang.String string, int stringLength)	Check if a string is ASCII only

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals, reversed, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Field Detail

useFastASCIISort

static boolean useFastASCIISort

true to use the faster ASCII sorting algorithm. Set to false when testing compatibility.

ASCII_SORT_ORDER

static final java.lang.String ASCII_SORT_ORDER

The sort order for the fast ASCII sort method.

See Also:

Constant Field Values

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

INSTANCE

private static final AlphanumComparator INSTANCE

ASCII_MAPPING

private static final byte[] ASCII_MAPPING

A mapping from ASCII characters to the default Collator order. At writing, the default rules can be found in CollationRules#DEFAULTRULES.

Constructor Detail

AlphanumComparator

private AlphanumComparator()

Constructs a new Alphanum Comparator.

Method Detail

getInstance

public static AlphanumComparator getInstance()

Replies the unique instance.

Returns:

the unique instance

compareString

private static int compareString(java.lang.String string1,
                                 int len1,
                                 java.lang.String string2,
                                 int len2)

Compare two ASCII strings in a manner compatible with the default Collator

Parameters:

string1 - The first string to compare

len1 - The length of the first string

string2 - The second string to compare

len2 - The length of the second string

Returns:

See String.compareToIgnoreCase(String) (e.g. string1.compareToIgnoreCase(string2)).

getChunk

private static java.lang.String getChunk(java.lang.String s,
                                         int slength,
                                         int marker)

Returns an alphanum chunk. Length of string is passed in for improved efficiency (only need to calculate it once).

Parameters:

s - string

slength - string length

marker - position

Returns:

alphanum chunk found at given position

isAscii

private static boolean isAscii(java.lang.String string,
                               int stringLength)

Check if a string is ASCII only

Parameters:

string - The string to check

stringLength - The length of the string (for performance reasons)

Returns:

true if the string only contains ascii characters

compareChunk

private static int compareChunk(java.lang.String thisChunk,
                                int thisChunkLength,
                                java.lang.String thatChunk,
                                int thatChunkLength)

Compare two string chunks

Parameters:

thisChunk - The first chunk to compare

thisChunkLength - The length of the first chunk (for performance reasons)

thatChunk - The second chunk to compare

thatChunkLength - The length of the second chunk (for performance reasons)

Returns:

The Comparator result

compare

public int compare(java.lang.String s1,
                   java.lang.String s2)

Specified by:

compare in interface java.util.Comparator<java.lang.String>