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January 30, 2014 18:56
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Alphanum, organizar lista de Strings
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/* | |
* 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 http://www.DaveKoelle.com | |
* | |
* | |
* This library is free software; you can redistribute it and/or | |
* modify it under the terms of the GNU Lesser General Public | |
* License as published by the Free Software Foundation; either | |
* version 2.1 of the License, or any later version. | |
* | |
* This library is distributed in the hope that it will be useful, | |
* but WITHOUT ANY WARRANTY; without even the implied warranty of | |
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
* Lesser General Public License for more details. | |
* | |
* You should have received a copy of the GNU Lesser General Public | |
* License along with this library; if not, write to the Free Software | |
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
* | |
*/ | |
import java.util.Comparator; | |
/** | |
* This is an updated version with enhancements made by Daniel Migowski, | |
* Andre Bogus, and David Koelle | |
* | |
* To convert to use Templates (Java 1.5+): | |
* - Change "implements Comparator" to "implements Comparator<String>" | |
* - Change "compare(Object o1, Object o2)" to "compare(String s1, String s2)" | |
* - Remove the type checking and casting in compare(). | |
* | |
* To use this class: | |
* Use the static "sort" method from the java.util.Collections class: | |
* Collections.sort(your list, new AlphanumComparator()); | |
*/ | |
public class Alphanum implements Comparator<String> | |
{ | |
private final boolean isDigit(char ch) | |
{ | |
return ch >= 48 && ch <= 57; | |
} | |
/** Length of string is passed in for improved efficiency (only need to calculate it once) **/ | |
private final String getChunk(String s, int slength, int marker) | |
{ | |
StringBuilder chunk = new StringBuilder(); | |
char c = s.charAt(marker); | |
chunk.append(c); | |
marker++; | |
if (isDigit(c)) | |
{ | |
while (marker < slength) | |
{ | |
c = s.charAt(marker); | |
if (!isDigit(c)) | |
break; | |
chunk.append(c); | |
marker++; | |
} | |
} else | |
{ | |
while (marker < slength) | |
{ | |
c = s.charAt(marker); | |
if (isDigit(c)) | |
break; | |
chunk.append(c); | |
marker++; | |
} | |
} | |
return chunk.toString(); | |
} | |
public int compare(String o1, String o2) | |
{ | |
if (!(o1 instanceof String) || !(o2 instanceof String)) | |
{ | |
return 0; | |
} | |
String s1 = (String)o1; | |
String s2 = (String)o2; | |
int thisMarker = 0; | |
int thatMarker = 0; | |
int s1Length = s1.length(); | |
int s2Length = s2.length(); | |
while (thisMarker < s1Length && thatMarker < s2Length) | |
{ | |
String thisChunk = getChunk(s1, s1Length, thisMarker); | |
thisMarker += thisChunk.length(); | |
String thatChunk = getChunk(s2, s2Length, thatMarker); | |
thatMarker += thatChunk.length(); | |
// If both chunks contain numeric characters, sort them numerically | |
int result = 0; | |
if (isDigit(thisChunk.charAt(0)) && isDigit(thatChunk.charAt(0))) | |
{ | |
// Simple chunk comparison by length. | |
int thisChunkLength = thisChunk.length(); | |
result = thisChunkLength - thatChunk.length(); | |
// If equal, the first different number counts | |
if (result == 0) | |
{ | |
for (int i = 0; i < thisChunkLength; i++) | |
{ | |
result = thisChunk.charAt(i) - thatChunk.charAt(i); | |
if (result != 0) | |
{ | |
return result; | |
} | |
} | |
} | |
} else | |
{ | |
result = thisChunk.compareTo(thatChunk); | |
} | |
if (result != 0) | |
return result; | |
} | |
return s1Length - s2Length; | |
} | |
} |
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