How do I get the content of a directory?

In this example you’ll see how to read the list of files inside a directory. To get this functionality we can use the File.listFiles() method. This method return an array of File object which can be either an instance of file or directory.

package org.kodejava.io;

import java.io.File;
import java.io.FilenameFilter;

public class DirectoryContentExample {
    public static void main(String[] args) {
        File gamesDir = new File("D:/Games");

        // Get a list of file under the specified directory above 
        // and return it as an abstract file object.
        File[] files = gamesDir.listFiles();

        if (files != null) {
            // Iterates the content of gamesDir directory, print 
            // it and check it whether it was a directory or a 
            // file.
            for (File file : files) {
                System.out.println(file + " is a "
                    + (file.isDirectory() ? "directory" : "file"));
            }
        }

        // Here we also get the list of file in the directory but
        // return it just as an array of String.
        String[] strings = gamesDir.list();
        if (strings != null) {
            for (String file : strings) {
                System.out.println("File = " + file);
            }
        }

        // Now we want to list the file in the directory but we 
        // just want a file with a .doc extension. To do this we 
        // first create a FilenameFilter which will be given to 
        // the listFiles() method to filter the listing process. 
        // The rule of filtering is implemented in the accept() 
        // method of the FilenameFilter interface, and we can write
        // it using lambda expression as follow.
        FilenameFilter filter = (dir, name) -> name.endsWith(".docx");

        // Give me just a .doc files in your directory.
        File[] docs = gamesDir.listFiles(filter);
        if (docs != null) {
            for (File doc : docs) {
                System.out.println("Doc file = " + doc);
            }
        }
    }
}

Here is the result of the program:

The File[] array returned:

D:\Games\AOE is a directory
D:\Games\Championship Manager 2017 is a directory
D:\Games\GameHouse is a directory
D:\Games\Sierra is a directory
D:\Games\testing.doc.docx is a file
D:\Games\TTD is a directory

The String[] array returned:

File = AOE
File = Championship Manager 2017
File = GameHouse
File = Sierra
File = testing.docx
File = TTD

The File[] array using FilenameFilter result:

Doc file = D:\Games\testing.docx

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Wayan

Founder at Kode Java

A programmer, runner and recreational diver, lives on the island of Bali, Indonesia. Programming in Java, Spring Framework, Hibernate / JPA, MySQL. To support me working on this project, buy me a cup of coffee, every little bit helps. Thank you.

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