Java - Read all .txt files in folder

Let's say, I have a folder called maps and inside maps I hav开发者_如何学编程e map1.txt, map2.txt, and map3.txt. How can I use Java and the BufferReader to read all of the .txt files in folder maps (if it is at all possible)?

Something like the following should get you going, note that I use apache commons FileUtils instead of messing with buffers and streams for simplicity...

File folder = new File("/path/to/files");
File[] listOfFiles = folder.listFiles();

for (int i = 0; i < listOfFiles.length; i++) {
  File file = listOfFiles[i];
  if (file.isFile() && file.getName().endsWith(".txt")) {
    String content = FileUtils.readFileToString(file);
    /* do somthing with content */
  } 
}

I would take @Andrew White answer (+1 BTW) one step further, and suggest you would use FileNameFilter to list only relevant files:

FilenameFilter filter = new FilenameFilter() {
    public boolean accept(File dir, String name) {
        return name.endsWith(".txt");
    }
};

File folder = new File("/path/to/files");
File[] listOfFiles = folder.listFiles(filter);

for (int i = 0; i < listOfFiles.length; i++) {
    File file = listOfFiles[i];
    String content = FileUtils.readFileToString(file);
    // do something with the file
}

    final File folder = new File("C:/Dev Tools/apache-tomcat-6.0.37/webapps/ROOT/somefile");
    for (final File fileEntry : folder.listFiles()) {
           System.out.println("FileEntry Directory "+fileEntry);

With NIO you can do the following:

Files.walk(Paths.get("/path/to/files"))
          .filter(Files::isRegularFile)
          .filter(path -> path.getFileName().toString().endsWith(".txt"))
          .map(FileUtils::readFileToString)
          // do something

To read the file contents you may use Files#readString but, as usual, you need to handle IOException inside lambda expression.

I think it's good way to read all .txt files from maps and sub folder's

 private static void addfiles (File input,ArrayList<File> files)
{
    if(input.isDirectory())
    {
        ArrayList <File> path = new ArrayList<File>(Arrays.asList(input.listFiles()));
        for(int i=0 ; i<path.size();++i)
        {
            if(path.get(i).isDirectory())
            {
                addfiles(path.get(i),files);
            }
            if(path.get(i).isFile())
            {
                String name=(path.get(i)).getName();
                if(name.lastIndexOf('.')>0)
                {
                    int lastIndex = name.lastIndexOf('.');
                    String str = name.substring(lastIndex);
                    if(str.equals(".txt"))
                    {
                        files.add(path.get(i));
                    }
                }
            }
        }
    }
    if(input.isFile())
    {
        String name=(input.getName());
        if(name.lastIndexOf('.')>0)
        {
            int lastIndex = name.lastIndexOf('.');
            String str = name.substring(lastIndex);
            if(str.equals(".txt"))
            {
                files.add(input);
            }
        }
    }

}

If you want a better way of doing this using the new java.nio api, then this is the way, taken from the java docs

Path dir = ...;
try (DirectoryStream<Path> stream =
     Files.newDirectoryStream(dir, "*.txt")) {
    for (Path entry: stream) {
        System.out.println(entry.getFileName());
    }
} catch (IOException x) {
    // IOException can never be thrown by the iteration.
    // In this snippet, it can // only be thrown by newDirectoryStream.
    System.err.println(x);
}

Using only JDK, If all your files are in one directory:

File dir = new File("path/to/files/");

for (File file : dir.listFiles()) {
    Scanner s = new Scanner(file);
    // do something with file
    s.close();
}

To exclude files, you can use listFiles(FileFilter)