Java File Extension Name Get getFileExtension(File file)

Description

Returns the extension of the file.

License

Apache License

Return

File extension, i.e. "java" for "FileSystemUtils.java", or null, if the file has no extension (i.e. if a filename contains no '.'), returns the empty string if the '.' is the filename's last character.

Declaration

public static String getFileExtension(File file)

Method Source Code

//package com.java2s;
/*-------------------------------------------------------------------------+
|                                                                          |
| Copyright 2005-2011 The ConQAT Project                                   |
|                                                                          |
| Licensed under the Apache License, Version 2.0 (the "License");          |
| you may not use this file except in compliance with the License.         |
| You may obtain a copy of the License at                                  |
|                                                                          |
|    http://www.apache.org/licenses/LICENSE-2.0                            |
|                                                                          |
| Unless required by applicable law or agreed to in writing, software      |
| distributed under the License is distributed on an "AS IS" BASIS,        |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and      |
| limitations under the License.                                           |
+-------------------------------------------------------------------------*/

import java.io.File;

public class Main {
    /**//from   ww w  .j  a v  a2 s .co m
     * Returns the extension of the file.
     * 
     * @return File extension, i.e. "java" for "FileSystemUtils.java", or
     *         <code>null</code>, if the file has no extension (i.e. if a
     *         filename contains no '.'), returns the empty string if the '.' is
     *         the filename's last character.
     */
    public static String getFileExtension(File file) {
        String name = file.getName();
        int posLastDot = name.lastIndexOf('.');
        if (posLastDot < 0) {
            return null;
        }
        return name.substring(posLastDot + 1);
    }
}