Is there a better way to do file exclusion using Java?

Question

What I am trying to do below is to remove files based on a array of prefixes, from files present in sourceDirectory. I am using prefixFileFilter to get the list of files with the Prefixes. After that I am removing these from the original list. Is there is any better approach.

package sriram;

import java.io.File;
import java.util.Arrays;
import java.util.List;

import org.apache.commons.io.filefilter.PrefixFileFilter;

public class FileFilterExample {
public static void main(String[] args) {
excludeFiles();
}

private static List<String> excludeFiles() {
String[] filesToBeExcluded = { "sri", "agnew" };
File sourceDirectory = new File(
        "C:\\Users\\sriram\\workspace1\\sample\\src");
String[] fileNames = sourceDirectory.list(new PrefixFileFilter(
        filesToBeExcluded));
List<String> listOfFiles = Arrays.asList(fileNames);
List<String> totalFiles = Arrays.asList(sourceDirectory.list());
totalFiles.removeAll(listOfFiles);
return totalFiles;
}
}

Thanks, Sriram

Answer 1

you can use java.io.FilenameFilter like:

    File[] totalFiles = sourceDirectory.listFiles(new FilenameFilter() {
        @Override
        public boolean accept(File dir, String name) {
            for (String s : filesToBeExcluded)
                if (name.startsWith(s)) return false;
            return true;
        }
    });

and make sure to mark filesToBeExcluded variable as final

Answer 2

Java 7 have had new features in nio2 : Files et Paths, it manage also Charset problems.

Here he sample of DirectoryStream.Filter

static void newDirectoryStreamFilter(final Path file1, final Object filter1) {
        System.out.println(sepFin + "\nFiles.newDirectoryStreamFilter("
            + file1.getFileName() + "), filtre: " + filter1 + sepDeb);
        try {
            final DirectoryStream.Filter<Path> filter = new DirectoryStream.Filter<Path>() {
                @Override
                public boolean accept(final Path file1) throws IOException {
                    for (String s : filesToBeExcluded)
                        if (file1.startsWith(s)) return false;
                        return true;
                }
            };
            try {
                for (final Path path : Files.newDirectoryStream(file1, filter)) {
                    System.out.format("%10d %s\n", Files.size(path),
                        path.toAbsolutePath());
                }
            } catch (final Exception e) {
                System.err.println(e.getMessage());
            }
        } catch (final Exception e) {
            System.err.println(e.getMessage());
        }

Answer 3

As you are already using commons.io, you could use the NotFileFilter: http://commons.apache.org/io/api-release/org/apache/commons/io/filefilter/NotFileFilter.html

and you will get:

private static List<String> getFileNamesWithoutExcludedPrefixes(File directory, String[] filesToBeExcluded) {
    return Arrays.asList(directory.list(new NotFileFilter(new PrefixFileFilter(filesToBeExcluded))));
}

(Argument checking could be added)

edit: oh and in your source:

totalFiles.removeAll(listOfFiles);

this can not work, because Arrays.asList() creates an immutable list.
You could change the line that creates the list to:

new ArrayList<String>(...);

If you need mutability.