How to detect if a file(with any extension) exist in java

Question

I am searching for a sound file in a folder and want to know if the sound file exist may it be .mp3,.mp4,etc.I just want to make sure that the filename(without extension) exists.

eg.File searching /home/user/desktop/sound/a

return found if any of a.mp3 or a.mp4 or a.txt etc. exist.

I tried this:

File f=new File(fileLocationWithExtension);

if(f.exist())
   return true;
else return false;

But here I have to pass the extension also otherwise its returning false always

To anyone who come here,this is the best way I figured out

    public static void main(String[] args) {
    File directory=new File(your directory location);//here /home/user/desktop/sound/
    final String name=yourFileName;  //here a;
            String[] myFiles = directory.list(new FilenameFilter() {
                public boolean accept(File directory, String fileName) {
                    if(fileName.lastIndexOf(".")==-1) return false;
                    if((fileName.substring(0, fileName.lastIndexOf("."))).equals(name))
                        return true;
                    else return false;
                }
            });
   if(myFiles.length()>0)
       System.Out.println("the file Exist");
}

Disadvantage:It will continue on searching even if the file is found which I never intended in my question.Any suggestion is welcome

Solution 1

This code will do the trick..

public static void listFiles() {

        File f = new File("C:/"); // use here your file directory path
        String[] allFiles = f.list(new MyFilter ());
        for (String filez:allFiles ) {
            System.out.println(filez);
        }
    }
}
        class MyFilter implements FilenameFilter {
        @Override
        //return true if find a file named "a",change this name according to your file name
        public boolean accept(final File dir, final String name) {
            return ((name.startsWith("a") && name.endsWith(".jpg"))|(name.startsWith("a") && name.endsWith(".txt"))|(name.startsWith("a") && name.endsWith(".mp3")|(name.startsWith("a") && name.endsWith(".mp4"))));

        }
    }

Above code will find list of files which has name a.
I used 4 extensions here to test(.jpg,.mp3,.mp4,.txt).If you need more just add them in boolean accept() method.

EDIT :
Here is the most simplified version of what OP wants.

public static void filelist()
    {
        File folder = new File("C:/");
        File[] listOfFiles = folder.listFiles();

    for (File file : listOfFiles)
    {
        if (file.isFile())
        {
            String[] filename = file.getName().split("\\.(?=[^\\.]+$)"); //split filename from it's extension
            if(filename[0].equalsIgnoreCase("a")) //matching defined filename
                System.out.println("File exist: "+filename[0]+"."+filename[1]); // match occures.Apply any condition what you need
        }
     }
}

Output:

File exist: a.jpg   //These files are in my C drive
File exist: a.png
File exist: a.rtf
File exist: a.txt
File exist: a.mp3
File exist: a.mp4

This code checks all the files of a path.It will split all filenames from their extensions.And last of all when a match occurs with defined filename then it will print that filename.

Solution 2

If you're looking for any file with name "a" regardless of the suffix, the glob that you're looking for is a{,.*}. The glob is the type of regular expression language used by shells and the Java API to match filenames. Since Java 7, Java has support for globs.

This Glob explained

• {} introduces an alternative. The alternatives are separated with ,. Examples:
  • {foo,bar} matches the filenames foo and bar.
  • foo{1,2,3} matches the filenames foo1, foo2 and foo3.
  • foo{,bar} matches the filenames foo and foobar - an alternative can be empty.
  • foo{,.txt} matches the filenames foo and foo.txt.
• * stands for any number of characters of any kind, including zero characters. Examples:
  • f* matches the filenames f, fa, faa, fb, fbb, fab, foo.txt - every file that's name starts with f.
• The combination is possible. a{,.*} is the alternatives a and a.*, so it matches the filename a as well as every filename that starts with a., like a.txt.

A Java program that lists all files in the current directory which have "a" as their name regardless of the suffix looks like this:

import java.io.*;
import java.nio.file.*;
public class FileMatch {
    public static void main(final String... args) throws IOException {
        try (final DirectoryStream<Path> stream = Files.newDirectoryStream(Paths.get("."), "a{,.*}")) {
            for (final Path entry : stream) {
                System.out.println(entry);
            }
        }
    }
}

or with Java 8:

import java.io.*;
import java.nio.file.*;
public class FileMatch {
    public static void main(final String... args) throws IOException {
        try (final DirectoryStream<Path> stream = Files.newDirectoryStream(Paths.get("."), "a{,.*}")) {
            stream.forEach(System.out::println);
        }
    }
}

If you have the filename in a variable and you want to see whether it matches the given glob, you can use the FileSystem.getPathMatcher() method to obtain a PathMatcher that matches the glob, like this:

final FileSystem fileSystem = FileSystems.getDefault();
final PathMatcher pathMatcher = fileSystem.getPathMatcher("glob:a{,.*}");
final boolean matches = pathMatcher.matches(new File("a.txt").toPath());

Comments

[agad]

Better: java.io.File.list(FilenameFilter); if (listOfFiles.length > 0) {System.out.println("found");}

[user207421]

Try it why? How does this answer the question?

[user2572367]

@ridoy i dont know how it works in java but asterisk would return any name and any extension that can be found in a directory

[user2511713]

"a" is actually the file name here.the folder contain many files(around 1000).will it be wise to use this method?

[user207421]

Not with java.io.File it doesn't. Obviously you haven't tried it. -1

[user2511713]

@EJP:It does.I do want to return true if /home/user/desktop/sound/a.* is available where * represents any type.

[user2511713]

@agad:FilenameFilter is "/home/user/desktop/sound/a" here?

[user207421]

@user2511713 Make up your mind. Either it doesn't work or it answers the question. Not both at the same time.

[Ruchira Gayan Ranaweera]

@user2511713 You can do it as this way

[ridoy]

@bowmore, i changed the code and it works perfectly now,so can you re-consider your downvote?

[ridoy]

@user2511713, inform me if this is what you want.

[agad]

I would slightly modify the accept method to improve the performance: public boolean accept(final File dir, final String name) { if (name.charAt(0) != 'a') { return false; if (name.endsWith(".jpg")||name.endsWith(".txt")||name.endsWith‌​(".mp3")||name.endsW‌​ith(".mp4")) { return true; } return false;}

[user2511713]

Your code will now work for .jpg,.mp3,.mp4,.txt .I want it to work with any file extension no matter what.have a look at my answer

[ridoy]

But you not mentioned that earlier in your question,u mentioned only 3 formats there.So make sure about what you want before asking a question and clearly mention that.