Listing files in a directory matching a pattern in Java

Question

I m looking for a way to get a list of files that match a pattern  pref regex  in a given directory   I ve found a tutorial online that uses apache s commons-io package with the following code   Collection getAllFilesThatMatchFilenameExtension String directoryName  String extension      File directory   new File directoryName     return FileUtils listFiles directory  new WildcardFileFilter extension   null       But that just returns a base collection  According to the docs it s a collection of java io File   Is there a way to do this that returns a type safe generic collection

User · Answer

import java io BufferedReader  import java io File  import java io FileReader  import java io IOException  import java util Map  import java util Scanner  import java util TreeMap   public class CharCountFromAllFilesInFolder        public static void main String   args throws IOException            try                 C  Users MD Desktop Test1              System out println  Enter Your FilePath                  Scanner sc   new Scanner System in                Map lt Character Integer gt  hm   new TreeMap lt Character  Integer gt                  String s1   sc nextLine                 File file   new File s1                File   filearr   file listFiles                 for  File file2   filearr                    System out println file2 getName                     FileReader fr   new FileReader file2                   BufferedReader br   new BufferedReader fr                   String s2   br readLine                    for  int i   0  i  lt  s2 length    i                          if  hm containsKey s2 charAt i                             hm put s2 charAt i   1                          if                     else                          hm put s2 charAt i   hm get s2 charAt i   1                          else                     for2                  System out println  The Char Count    hm                  for1             try         catch Exception e               System out println  Please Give Correct File Path                catch

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Since Java 8 you can use lambdas and achieve shorter code   File dir   new File xmlFilesDirectory   File   files   dir listFiles  d  name  - gt  name endsWith   xml

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See File listFiles FilenameFilter    File dir   new File       File    files   dir listFiles new FilenameFilter          Override     public boolean accept File dir  String name            return name endsWith   xml               for  File xmlfile   files        System out println xmlfile

User · Answer

What about a wrapper around your existing code   public Collection lt File gt  getMatchingFiles  String directory  String extension          return new ArrayList lt File gt               getAllFilesThatMatchFilenameExtension  directory  extension           I will throw a warning though  If you can live with that warning  then you re done

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Since java 7 you can the java nio package to achieve the same result   Path dir        List lt File gt  files   new ArrayList lt  gt     try  DirectoryStream lt Path gt  stream   Files newDirectoryStream dir      java class jar           for  Path entry  stream            files add entry toFile               return files    catch  IOException x        throw new RuntimeException String format  error reading folder  s   s       dir      x getMessage         x

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The following code will create a list of files based on the accept method of the FileNameFilter   List lt File gt  list   Arrays asList dir listFiles new FilenameFilter             Override         public boolean accept File dir  String name                return name endsWith   exe       or something else

[java] Listing files in a directory matching a pattern in Java

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