com.alee.utils.file.FileNameComparator Maven / Gradle / Ivy
/*
* This file is part of WebLookAndFeel library.
*
* WebLookAndFeel library is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* WebLookAndFeel 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with WebLookAndFeel library. If not, see .
*/
package com.alee.utils.file;
import java.io.Serializable;
import java.util.Comparator;
import java.util.Locale;
/**
* File names comparator.
* It is insensitive to case but sensitive to integer numbers within the name.
*
* @author Mikle Garin
*/
public class FileNameComparator implements Comparator, Serializable
{
@Override
public int compare ( final String name1, final String name2 )
{
if ( name1 != null && name2 != null )
{
final String lower1 = name1.toLowerCase ( Locale.ROOT );
final String lower2 = name2.toLowerCase ( Locale.ROOT );
int thisMarker = 0;
int thatMarker = 0;
final int s1Length = lower1.length ();
final int s2Length = lower2.length ();
while ( thisMarker < s1Length && thatMarker < s2Length )
{
final String thisChunk = getChunk ( lower1, s1Length, thisMarker );
thisMarker += thisChunk.length ();
final String thatChunk = getChunk ( lower2, s2Length, thatMarker );
thatMarker += thatChunk.length ();
// If both chunks contain numeric characters, sort them numerically
int result;
if ( isDigit ( thisChunk.charAt ( 0 ) ) && isDigit ( thatChunk.charAt ( 0 ) ) )
{
// Simple chunk comparison by length.
final 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;
}
return 0;
}
/**
* Returns name chunk starting from marker position.
* Length of string is passed in for improved efficiency (only need to calculate it once).
*
* @param name full name
* @param slength full name length
* @param marker chunk starting position
* @return name chunk starting from marker position
*/
protected String getChunk ( final String name, final int slength, int marker )
{
final StringBuilder chunk = new StringBuilder ();
char c = name.charAt ( marker );
chunk.append ( c );
marker++;
if ( isDigit ( c ) )
{
while ( marker < slength )
{
c = name.charAt ( marker );
if ( !isDigit ( c ) )
{
break;
}
chunk.append ( c );
marker++;
}
}
else
{
while ( marker < slength )
{
c = name.charAt ( marker );
if ( isDigit ( c ) )
{
break;
}
chunk.append ( c );
marker++;
}
}
return chunk.toString ();
}
/**
* Returns whether or not specified character is digit.
*
* @param character character to check
* @return {@code true} if specified character is digit, {@code false} otherwise
*/
protected boolean isDigit ( final char character )
{
return character >= 48 && character <= 57;
}
}