file.list method not working in java

Question

I have created a dirctory named test. Within this directory I have created a file named test.txt. When I execute the program below, the output for list method on cmd does not show the list of files in test directory.

Following is my code:

import java.io.*;

public class f1{
    public static void main(String args[]){
    try{
        File f = new File("test");
                System.out.println(f.exists());
                System.out.println(f.isDirectory());
                System.out.println(f.isFile());
                System.out.println(f.list());
    }
    catch(Exception e){

    }
}

}

Following is the output:

 true
 true
 false
 [Ljava.io.File;@15db9742

It's an array of Strings, you need to iterate over it and print the elements separately. Check this question: http://stackoverflow.com/questions/409784/whats-the-simplest-way-to-print-an-array — NeplatnyUdaj, Mar 05 '15 at 13:40

score 5 · Accepted Answer · answered Mar 05 '15 at 13:42

5

file.list() returns a String[]. Since arrays don't have an implementation of toString() (which is called when using println), it uses the default implementation of Object, which returns ClassName@hashCode. To convert an array to a String, you can use the java.util.Arrays class.

import java.util.Arrays;
// ...
System.out.println(Arrays.toString(file.list()));

answered Mar 05 '15 at 13:42

Clashsoft

11,553
5
40
79

Nicely Explained. Thanks a lot! – user3382203 Mar 05 '15 at 13:49

score 1 · Answer 2 · answered Mar 05 '15 at 13:43

1

You cannot print arrays directly. File.list() returns an array of Strings. There's a utility class Arrays which will allow you to print it without iterating over it manually:

Arrays.toString(f.list())

answered Mar 05 '15 at 13:43

NeplatnyUdaj

6,052
6
43
76

score 1 · Answer 3 · answered Mar 05 '15 at 13:44

1

file.list()

Returns an array of strings naming the files and directories in the directory denoted by this abstract pathname.

Java Docs

answered Mar 05 '15 at 13:44

singhakash

7,891
6
31
65

score -2 · Answer 4 · answered Mar 05 '15 at 13:42

-2

list returns a string array.

so if you specify a correct file URI then it should work.

import java.io.*;

public class f1
{
    public static void main(String args[]){
        try
        {
            File f = new File("test");
                    System.out.println(f.exists());
                    System.out.println(f.isDirectory());
                    System.out.println(f.isFile());
                    System.out.println(f.list());


                    for (int i = 0; i < f.list().length; i++)
                    {
                        System.out.println(f.list()[i]);
                    }
        }
        catch(Exception e){

        }
    }
}

answered Mar 05 '15 at 13:42

Blaatz0r

1,205
1
12
24

4

Do you really think you should call `f.list()` this many times instead of using a local variable? – Clashsoft Mar 05 '15 at 13:43
Dude i am just giving an example. – Blaatz0r Mar 05 '15 at 13:43
3

And if you don't want to use a variable, at least use an enhanced `for`-loop. – Florent Bayle Mar 05 '15 at 13:44
it's a bloody example that only shows that it is a array of strings. he should find his own implementation. – Blaatz0r Mar 05 '15 at 13:47
It could also throw a NullPointerException: From [`File.list()`](http://docs.oracle.com/javase/7/docs/api/java/io/File.html#list()): If this abstract pathname does not denote a directory, then this method returns null – Albert Mar 05 '15 at 13:47
1

READ: so if you specify a correct file URI then it should work. – Blaatz0r Mar 05 '15 at 13:48
Chill I was just pointing it out. – Clashsoft Mar 05 '15 at 13:58
downvoting isn't a way to point things out. – Blaatz0r Mar 05 '15 at 14:05
2

What tells you that I downvoted your answer? – Clashsoft Mar 05 '15 at 14:06

file.list method not working in java

4 Answers4