Delete Files Older than (x) Days?

You can use File.lastModified() to get the last modified time of a file/directory.

Can be used like this:

long diff = new Date().getTime() - file.lastModified();

if (diff > x * 24 * 60 * 60 * 1000) {
    file.delete();
}

Which deletes files older than x (an int) days.

Using Apache utils is probably the easiest. Here is the simplest solution I could come up with.

public void deleteOldFiles() {
    Date oldestAllowedFileDate = DateUtils.addDays(new Date(), -3); //minus days from current date
    File targetDir = new File("C:\\TEMP\\archive\\");
    Iterator<File> filesToDelete = FileUtils.iterateFiles(targetDir, new AgeFileFilter(oldestAllowedFileDate), null);
    //if deleting subdirs, replace null above with TrueFileFilter.INSTANCE
    while (filesToDelete.hasNext()) {
        FileUtils.deleteQuietly(filesToDelete.next());
    }  //I don't want an exception if a file is not deleted. Otherwise use filesToDelete.next().delete() in a try/catch
}

Commons IO has built-in support for filtering files by age with its AgeFileFilter. Your DeleteFiles could just look like this:

import java.io.File;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.filefilter.AgeFileFilter;
import static org.apache.commons.io.filefilter.TrueFileFilter.TRUE;

// a Date defined somewhere for the cutoff date
Date thresholdDate = <the oldest age you want to keep>;

public void DeleteFiles(File file) {
    Iterator<File> filesToDelete =
        FileUtils.iterateFiles(file, new AgeFileFilter(thresholdDate), TRUE);
    for (File aFile : filesToDelete) {
        aFile.delete();
    }
}

Update: To use the value as given in your edit, define the thresholdDate as:

Date tresholdDate = new Date(1361635382096L);