How would you write a "wildcard" in a filefilter?

Question

How would you go about to have a wildcard instead of the "*" in the following filefilter;
          File[] files = new File("./resultat/resultat_" + "*" + "_" + index[0]).listFiles (new FileFilter () {
                public boolean accept (File file) {
                    return ! file.isDirectory ();
          });All help appriciated
- Karl XII

Answer 1

Shouldn't "a*" accept all files that begins with "a" and ends with whatever?No. "*" in regexp is a not a wildcard match. Instead it matches one or more instances of the preceeding
value.
Therefore "a*" will match "a", "aa", "aaa", "aaaa" etc but will not match anything which does not end in
an "a".
The following might help you out. (not the most elegent expression but it will do
import java.util.regex.*;
public class RegExp{
  public static void main(String[] args) {
  Pattern p = Pattern.compile("a*b");     
  Matcher m = p.matcher("aaaab");     
  System.out.println(m.matches());                    
  // interesting bit here
  // match one or more occurances of any characters in the ASCII charset  (the \\p{ASCII}* bit   
  p = Pattern.compile("hello_\\p{ASCII}*_b");     
  m = p.matcher("hello_wibble_b");     
  System.out.println(m.matches());
}