Java8 - streamとDirectoryWalkerで効率よくファイル探索

Java IO CommonsのDirectoryWalkerとstreamを組み合わせて，効率よくファイルシステム上のデータを探すコード．かなり荒削りのサンプルだが，とりあえず動く．

package org.tanuneko.tanukin;

import org.apache.commons.io.DirectoryWalker;
import org.apache.commons.io.filefilter.FileFilterUtils;
import org.apache.commons.io.filefilter.IOFileFilter;

import java.io.File;
import java.io.FileFilter;
import java.io.IOException;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.stream.Collectors;

public class DirWalker extends DirectoryWalker<File> {

    private static FileFilter filter = getFilter();

    public DirWalker() {

        super( filter,-1 );

    }

    protected void handleFile( File file, int depth, Collection<File> results ) {

        results.add( file );

    }

    public Collection<File> start( File startDir ) throws IOException {
        Collection<File> results = new ConcurrentLinkedQueue<File>();
        super.walk( startDir, results );
        return results;
    }

    public static void main(String args[] ) throws IOException {

        DirWalker walker = new DirWalker();
        System.out.println(
                        walker.start(new File("C:\\cygwin\\srv")).parallelStream()
                        .map(x -> x.getAbsolutePath())
                        .collect(Collectors.toStringJoiner("\n"))
                        .toString());

    }

    // if you want to handle directory, define below
    /*
    protected boolean handleDirectory( File dir, int depth, Collection<File> results ) {

        if( ".svn".equals( dir.getName() ) ) {
            return false;
        }
        else {
            return true;
        }
    }
    */

    private static FileFilter getFilter() {

        //    you can define filter
        //    IOFileFilter suffixFilt =  FileFilterUtils.suffixFileFilter( ".txt" );
        //    FileFilterUtils.makeSVNAware( suffixFilt );
        //   FileFilter filter = FileFilterUtils.or( suffixFilt );
        //    return filter;
        return null;

    }

}