File list() method in Java with Examples

The list() method is a part of File class.The function returns an array of string denoting the files in a given abstract pathname if the path name is a directory else returns null. The function is an overloaded function. One of the function does not have any parameter and the other function takes FilenameFilter object as parameter

Function Signature:

public String[] list()
public String[] list(FilenameFilter f)

Function Syntax:

file.list()
file.list(filter)

Parameters: The function is an overloaded function. One of the function does not have any parameter and the other function takes FilenameFilter object as a parameter

Return value: The function returns a string array, or null value if the file object is file.

Exception: This method throws Security Exception if the function is not allowed write access to the file.

Below programs will illustrate the use of the list() function

Example 1: We will try to find all the files and directories in a given directory

// Java program to demonstrate the
// use of list() function

import java.io.*;

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

        // try-catch block to handle exceptions
        try {

            // Create a file object
            File f = new File("f:\\program");

            // Get all the names of the files present
            // in the given directory
            String[] files = f.list();

            System.out.println("Files are:");

            // Display the names of the files
            for (int i = 0; i < files.length; i++) {
                System.out.println(files[i]);
            }
        }
        catch (Exception e) {
            System.err.println(e.getMessage());
        }
    }
}

Output:

Files are:
1232.txt
1245.txt
5671.txt
program1

Example 2: We will try to find all the files and directories in a given directory whose names start with “12”

// Java program to demonstrate the
// use of list() function

import java.io.*;

public class solution {
    public static void main(String atry-catch  {

        // try catch block to handle exceptions
        try {

            // Create a file object
            File f = new File("f:\\program");

            // Create a FilenameFilter
            FilenameFilter filter = new FilenameFilter() {

                public boolean accept(File f, String name)
                {
                    return name.startsWith("12");
                }
            };

            // Get all the names of the files present
            // in the given directory
            // and whose names start with "12"
            String[] files = f.list(filter);

            System.out.println("Files are:");

            // Display the names of the files
            for (int i = 0; i < files.length; i++) {
                System.out.println(files[i]);
            }
        }
        catch (Exception e) {
            System.err.println(e.getMessage());
        }
    }

Output:

Files are:
1232.txt
1245.txt

The programs might not run in an online IDE. please use an offline IDE and set the Parent file of the file