Java/File Input Output/FilenameFilter

Accepts a selection if it is acceptable to both of two FilenameFilters

   

import java.io.File;
import java.io.FilenameFilter;
/**
 * Accepts a selection if it is acceptable to both of two {@link FilenameFilter}s.
 * This takes two {@link FilenameFilter}s as input.
 *
 * <p>Eg., to print all files beginning with <code>A</code> and ending with <code>.java</code>:</p>
 *
 * <pre>
 * File dir = new File(".");
 * String[] files = dir.list( new AndFileFilter(
 *         new PrefixFileFilter("A"),
 *         new ExtensionFileFilter(".java")
 *         )
 *     );
 * for ( int i=0; i&lt;files.length; i++ )
 * {
 *     System.out.println(files[i]);
 * }
 * </pre>
 *
 * @author 
 * @version $Revision: 494012 $ $Date: 2007-01-08 11:23:58 +0100 (Mo, 08 Jan 2007) $
 * @since 4.0
 */
public class AndFileFilter
    implements FilenameFilter
{
    private final FilenameFilter m_filter1;
    private final FilenameFilter m_filter2;
    public AndFileFilter( final FilenameFilter filter1, final FilenameFilter filter2 )
    {
        m_filter1 = filter1;
        m_filter2 = filter2;
    }
    public boolean accept( final File file, final String name )
    {
        return m_filter1.accept( file, name ) && m_filter2.accept( file, name );
    }
}

A simple file filter for a particular file extension

   
//revised from prefuse
import java.io.File;
import java.util.ArrayList;
import java.util.Iterator;
import javax.swing.filechooser.FileFilter;
/**
 * A simple file filter for a particular file extension.
 *  
 * @author 
 */
public class SimpleFileFilter extends FileFilter {
    
    private ArrayList exts = new ArrayList();
    private String desc;
    private Object data;
    
    /**
     * Create a new SimpleFileFilter.
     * @param ext the file extension
     * @param desc a description of the file type
     */
    public SimpleFileFilter(String ext, String desc) {
        addExtension(ext);
        this.desc = desc;
    }
    
    /**
     * Create a new SimpleFileFilter.
     * @param ext the file extension
     * @param desc a description of the file type
     * @param data user-provided attached object
     */
    public SimpleFileFilter(String ext, String desc, Object data) {
        addExtension(ext);
        this.desc = desc;
        this.data = data;
    }
    
    /**
     * Add a file extension to this file filter.
     * @param ext the file extension to add
     */
    public void addExtension(String ext) {
        exts.add(ext.toLowerCase());
    }
    
    /**
     * @see javax.swing.filechooser.FileFilter#accept(java.io.File)
     */
    public boolean accept(File f) {
        if ( f == null )
            return false;
        if ( f.isDirectory() )
            return true;
        String extension = getExtension(f);
        if ( extension == null ) return false;
        for ( Iterator iter = exts.iterator(); iter.hasNext(); ) {
            String ext = (String)iter.next();
            if ( ext.equalsIgnoreCase(extension) )
                return true;
        }
        return false;
    }
    /**
     * Returns the extension for a file or null if there is none
     * @param f the input file
     * @return the file extension, or null if none
     */
    public static String getExtension(File f) {
        return (f != null ? getExtension(f.getName()) : null);
    }
    /**
     * Returns the extension for a file or null if there is none
     * @param filename the input filename
     * @return the file extension, or null if none
     */
    public static String getExtension(String filename) {
        int i = filename.lastIndexOf(".");
        if ( i>0 && i<filename.length()-1 ) {
            return filename.substring(i+1).toLowerCase();
        } else {
            return null;
        }
    }
    /**
     * Get a user-provided attached object.
     * @return the user-provided attached object
     */
    public Object getUserData() {
        return data;
    }
    
    /**
     * @see javax.swing.filechooser.FileFilter#getDescription()
     */
    public String getDescription() {
        return desc;
    }
    
    /**
     * Get the first file extension associated with this filter.
     * @return the first file extension associated with this filter
     */
    public String getExtension() {
        return (String)exts.get(0);
    }
    
} // end of class SimpleFileFilter

Inverted File Filter

   
/****************************************************************
 * Licensed to the Apache Software Foundation (ASF) under one   *
 * or more contributor license agreements.  See the NOTICE file *
 * distributed with this work for additional information        *
 * regarding copyright ownership.  The ASF licenses this file   *
 * to you 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;
import java.io.FilenameFilter;
/**
 * This takes a <code>FilenameFilter<code> as input and inverts the selection.
 * This is used in retrieving files that are not accepted by a filter.
 *
 * @author 
 * @version CVS $Revision: 494012 $ $Date: 2007-01-08 11:23:58 +0100 (Mo, 08 Jan 2007) $
 * @since 4.0
 */
public class InvertedFileFilter
    implements FilenameFilter
{
    private final FilenameFilter m_originalFilter;
    public InvertedFileFilter( final FilenameFilter originalFilter )
    {
        m_originalFilter = originalFilter;
    }
    public boolean accept( final File file, final String name )
    {
        return !m_originalFilter.accept( file, name );
    }
}

only display files that use the .html extension.

   
import java.io.File;
import java.io.FilenameFilter;
class DirListOnly {
  public static void main(String args[]) {
    String dirname = "/java";
    File f1 = new File(dirname);
    FilenameFilter only = new OnlyExt("html");
    String s[] = f1.list(only);
    for (int i = 0; i < s.length; i++) {
      System.out.println(s[i]);
    }
  }
}
class OnlyExt implements FilenameFilter {
  String ext;
  public OnlyExt(String ext) {
    this.ext = "." + ext;
  }
  public boolean accept(File dir, String name) {
    return name.endsWith(ext);
  }
}

Removes the file extension from the given file name.

  
import java.net.URL;
/* 
 * JCommon : a free general purpose class library for the Java(tm) platform
 * 
 *
 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
 * 
 * Project Info:  http://www.jfree.org/jcommon/index.html
 *
 * 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 
 * (at your option) 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.  
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
 * in the United States and other countries.]
 * 
 * ------------
 * IOUtils.java
 * ------------
 * (C)opyright 2002-2004, by Thomas Morgner and Contributors.
 *
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *
 * $Id: IOUtils.java,v 1.8 2009/01/22 08:34:58 taqua Exp $
 *
 * Changes
 * -------
 * 26-Jan-2003 : Initial version
 * 23-Feb-2003 : Documentation
 * 25-Feb-2003 : Fixed Checkstyle issues (DG);
 * 29-Apr-2003 : Moved to jcommon
 * 04-Jan-2004 : Fixed JDK 1.2.2 issues with createRelativeURL;
 *               added support for query strings within these urls (TM);
 */

/**
 * The IOUtils provide some IO related helper methods.
 *
 * @author Thomas Morgner.
 */
public class Main {
  /**
   * Removes the file extension from the given file name.
   *
   * @param file the file name.
   * @return the file name without the file extension.
   */
  public String stripFileExtension(final String file) {
      final int idx = file.lastIndexOf(".");
      // handles unix hidden files and files without an extension.
      if (idx < 1) {
          return file;
      }
      return file.substring(0, idx);
  }
}

Returns the file extension of the given file name. The returned value will contain the dot.

  
import java.net.URL;
/* 
 * JCommon : a free general purpose class library for the Java(tm) platform
 * 
 *
 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
 * 
 * Project Info:  http://www.jfree.org/jcommon/index.html
 *
 * 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 
 * (at your option) 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.  
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
 * in the United States and other countries.]
 * 
 * ------------
 * IOUtils.java
 * ------------
 * (C)opyright 2002-2004, by Thomas Morgner and Contributors.
 *
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *
 * $Id: IOUtils.java,v 1.8 2009/01/22 08:34:58 taqua Exp $
 *
 * Changes
 * -------
 * 26-Jan-2003 : Initial version
 * 23-Feb-2003 : Documentation
 * 25-Feb-2003 : Fixed Checkstyle issues (DG);
 * 29-Apr-2003 : Moved to jcommon
 * 04-Jan-2004 : Fixed JDK 1.2.2 issues with createRelativeURL;
 *               added support for query strings within these urls (TM);
 */

/**
 * The IOUtils provide some IO related helper methods.
 *
 * @author Thomas Morgner.
 */
public class Main {
  /**
   * Returns the file extension of the given file name.
   * The returned value will contain the dot.
   *
   * @param file the file name.
   * @return the file extension.
   */
  public String getFileExtension(final String file) {
      final int idx = file.lastIndexOf(".");
      // handles unix hidden files and files without an extension.
      if (idx < 1) {
          return "";
      }
      return file.substring(idx);
  }
}

This filter accepts Files that are directories

   
/****************************************************************
 * Licensed to the Apache Software Foundation (ASF) under one   *
 * or more contributor license agreements.  See the NOTICE file *
 * distributed with this work for additional information        *
 * regarding copyright ownership.  The ASF licenses this file   *
 * to you 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;
import java.io.FilenameFilter;
/**
 * This filter accepts <code>File</code>s that are directories.
 * <p>Eg., here is how to print out a list of the current directory"s subdirectories:</p>
 *
 * <pre>
 * File dir = new File(".");
 * String[] files = dir.list( new DirectoryFileFilter() );
 * for ( int i=0; i&lt;files.length; i++ )
 * {
 *     System.out.println(files[i]);
 * }
 * </pre>
 *
 * @author 
 * @version $Revision: 494012 $ $Date: 2007-01-08 11:23:58 +0100 (Mo, 08 Jan 2007) $
 * @since 4.0
 */
public class DirectoryFileFilter
    implements FilenameFilter
{
    public boolean accept( final File file, final String name )
    {
        return new File( file, name ).isDirectory();
    }
}