Returns the filename extension without the dot using regex. - Java java.io

Java examples for java.io:File Extension Name

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Description

Returns the filename extension without the dot using regex.

Demo Code

/*/*from   w ww  .j ava2  s .c  om*/
 * JCamStream, simple Java application for video surveillance from webcams.
 * Copyright (C) 2011 Papa Issa DIAKHATE (paissad).
 * 
 * This program 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.
 * 
 * This program 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
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
//package com.java2s;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] argv) throws Exception {
        String filename = "java2s.com";
        System.out.println(getFilenameExtension(filename));
    }

    /**
     * Returns the filename extension without the dot.
     * 
     * @param filename
     * @return The extension without the dot, or <code>null</code> if the
     *         filename is null, or an empty String if the file has no
     *         extension.
     */
    public static String getFilenameExtension(final String filename) {
        if (filename == null)
            return null;
        Pattern pattern = Pattern.compile("\\.[^\\.]*$");
        Matcher matcher = pattern.matcher(filename);
        int count = matcher.groupCount();
        return (matcher.find()) ? matcher.group(count) : "";
    }
}

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