Java PathMatcher filter a directory

Introduction

There are several special characters summarized in the following table:

Special Symbols
 Meaning
*
 Matches zero or more characters of a name component without crossing directory boundaries

 Matches zero or more characters crossing directory boundaries
?
 Matches exactly one character of a name component
\
 The escape character used to match the special symbols
[]




 Matches a single character found within the brackets.
- matches a range.
! means negation.
*, ?, and \ characters match themselves
- matches itself if it is the first character within the brackets or the first character after the !.
{}

 Multiple sub patterns.
These patterns are grouped together using the curly braces, but are separated within the curly braces by commas.

The following table presents several examples of useful patterns:

Pattern String Will Match
*.java Any filename that ends with .java
*.{java,class,jar} Any file that ends with .java, .class, or .jar
java*[ph].exeOnly those files that start with java and are terminated with either a p.exe or h.exe
j*r.exe Those files that start with a j and end with an r.exe

Instead of using the glob: prefix, we can use regular expressions instead.

To do this, use a reg: prefix followed by a regular expression. 

import java.io.IOException;
import java.nio.file.DirectoryIteratorException;
import java.nio.file.DirectoryStream;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.PathMatcher;
import java.nio.file.Paths;

public class Main {

   public static void main(String[] args) {

      Path directory = Paths.get("C:/bin");
      PathMatcher pathMatcher = FileSystems.getDefault().getPathMatcher("glob:java?.exe");
      try (DirectoryStream<Path> directoryStream = Files.newDirectoryStream(directory, "java*.exe")) {
         for (Path file : directoryStream) {
            if (pathMatcher.matches(file.getFileName())) {
               System.out.println(file.getFileName());
            }/*from  www  . ja v a  2s.  c o  m*/
         }
      } catch (IOException | DirectoryIteratorException ex) {
         ex.printStackTrace();
      }
   }
}



PreviousNext

Related