CODEWITHSUNDEEP
javaregex
TheGuyNextDoor
TheGuyNextDoor

Reputation: 7937

Regex for files in a directory

Is it possible to use a regular expression to get filenames for files matching a given pattern in a directory without having to manually loop through all the files.

Upvotes: 11

Views: 30158

Answers (3)

Bart Kiers
Bart Kiers

Reputation: 170148

You could use File.listFiles(FileFilter):

public static File[] listFilesMatching(File root, String regex) {
    if(!root.isDirectory()) {
        throw new IllegalArgumentException(root+" is no directory.");
    }
    final Pattern p = Pattern.compile(regex); // careful: could also throw an exception!
    return root.listFiles(new FileFilter(){
        @Override
        public boolean accept(File file) {
            return p.matcher(file.getName()).matches();
        }
    });
}

EDIT

So, to match files that look like: TXT-20100505-XXXX.trx where XXXX can be any four successive digits, do something like this:

listFilesMatching(new File("/some/path"), "XT-20100505-\\d{4}\\.trx")

EDIT

Starting with Java8 the complete 'return'-part can be written with a lamda-statement:

    return root.listFiles((File file) -> p.matcher(file.getName()).matches());

Upvotes: 29

hanisa
hanisa

Reputation: 1

package regularexpression;

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

public class RegularFile {
    public static void main(String[] args) {
        new RegularFile();
    }

    public RegularFile() {

        String fileName = null;
        boolean bName = false;
        int iCount = 0;
        File dir = new File("C:/regularfolder");
        File[] files = dir.listFiles();
        System.out.println("List Of Files ::");

        for (File f : files) {

            fileName = f.getName();
            System.out.println(fileName);

            Pattern uName = Pattern.compile(".*l.zip.*");
            Matcher mUname = uName.matcher(fileName);
            bName = mUname.matches();
            if (bName) {
                iCount++;

            }
        }
        System.out.println("File Count In Folder ::" + iCount);

    }
}

Upvotes: 0

Ilya Saunkin
Ilya Saunkin

Reputation: 19810

implement FileFilter (just requires that you override the method 

public boolean accept(File f)

then, every time that you'll request the list of files, jvm will compare each file against your method. Regex cannot and shouldn't be used as java is a cross platform language and that would cause implications on different systems.

Upvotes: 1

Related Questions