`NewDirectoryStream`

How can we loop over all the files from a folder? In Java, we can use the Files class and call Files.newDirectoryStream, and then use a for-loop.

With this method, we need to get a Path representing the target directory. Then, we need to wrap the method call in an exception-handling block, as it might cause an error.

Example

This program imports the required Java IO classes with 2 import statements at the top. This is necessary to more easily access the types.

Step 1 We call getPath with a folder name on the default file system. This accesses a "programs" folder in the working directory.

Step 2 We call Files.newDirectoryStream, and pass the Path object we created. This returns a DirectoryStream.

Step 3 We use a for-loop over the Path instances in the DirectoryStream, and print each one to System.out.

Step 4 It is possible for Files.newDirectoryStream to throw an exception, so we may want to handle that here.

import java.io.*;
import java.nio.file.*;

public class Program {
    public static void main(String[] args) {

        // Step 1: get path to a folder.
        var path = FileSystems.getDefault().getPath("programs");

        // Step 2: call Files.newDirectoryStream to get paths from a folder.
        try (var stream = Files.newDirectoryStream(path)) {
            // Step 3: enumerate the paths in a for-loop and print them out.
            for (Path entry : stream) {
                System.out.println("Path: " + entry);
            }
        } catch (IOException exception) {
            // Step 4: if an error occurred, handle it.
            System.err.println("Error");
        }
    }
}Path: programs/program.go
Path: programs/example.txt
Path: programs/Program.java
Path: programs/program.py
Path: programs/program.scala
Path: programs/program.swift
Path: programs/program.php
Path: programs/program.js

With the Path and DirectoryStream types, we can access all the paths in a folder in an elegant way. Occasionally an exception may occur if the directory is missing.