How can I read only text files in a directory?

Question

In the program below I'm currently reading files in a directory. However I'd like to only read .txt files. How can I read only the .text files located in the directory.

import java.io.*;

public class Data {

    public static void main(String[] args) throws IOException {
        String target_dir = "C:\\Files";
        String textfile;
        File dir = new File(target_dir);
        File[] files = dir.listFiles();

        for (File textfiles : files) {
            if (textfiles.isFile()) {

                BufferedReader inputStream = null;

                try {
                    inputStream = new BufferedReader(new FileReader(textfiles));
                    String line;

                    while ((line = inputStream.readLine()) != null) {
                        System.out.println(line);
                    }
                } finally {
                    if (inputStream != null) {
                        inputStream.close();
                    }
                }
            }
        }
    }

}

score 3 · Answer 1 · answered Apr 30 '15 at 15:48

You can use java.io.FilenameFilter to filter files in a directory.

import java.io.*;

public class Data {

    public static void main(String[] args) throws IOException {
        String target_dir = "C:\\Files";
        File dir = new File(target_dir);
        FilenameFilter textFileFilter = new FilenameFilter() {

            @Override
            public boolean accept(File dir, String name) {
                return name.endsWith(".txt");
            }
        };
        File[] files = dir.listFiles(textFileFilter);

       for (File textfiles : files) {
           if (textfiles.isFile()) {

               BufferedReader inputStream = null;

               try {
                   inputStream = new BufferedReader(new FileReader(textfiles));
                   String line;

                   while ((line = inputStream.readLine()) != null) {
                       System.out.println(line);
                   }
                } finally {
                    if (inputStream != null) {
                        inputStream.close();
                }
            }
        }
    }
}

}

Ryan · Accepted Answer · 2015-05-08T14:06:40.997

2

Try checking the extension

import java.io.*;

public class Data {

    public static void main(String[] args) throws IOException {
        String target_dir = "C:\\Files";
        String textfile;
        File dir = new File(target_dir);
        File[] files = dir.listFiles();

        for (File textfiles : files) {
            if (textfiles.isFile() && textfiles.getName().endsWith(".txt")) {

                BufferedReader inputStream = null;

                try {
                    inputStream = new BufferedReader(new FileReader(textfiles));
                    String line;

                    while ((line = inputStream.readLine()) != null) {
                        System.out.println(line);
                    }
                } finally {
                    if (inputStream != null) {
                        inputStream.close();
                    }
                }
            }
        }
    }
}

edited May 08 '15 at 14:06

answered Apr 30 '15 at 15:39

Ryan

2,058
1
15
29

The extension doesn't actually tell you whats in the file. – Distjubo Apr 30 '15 at 15:40
But it should grab all the .txt files, which is what he wants. – Ryan Apr 30 '15 at 15:42
But @Distjubo's answer looks to be the cleaner better answer, although that is not 100% either. – Hovercraft Full Of Eels Apr 30 '15 at 15:42
Sorry @Ryan for my recommendation. Actually, the headline says he wants to read text files, which is what I would do. – Distjubo Apr 30 '15 at 15:44
@FullNelson in that case, can you accept my answer? :) Thanks – Ryan Apr 30 '15 at 15:49
@Ryan check for ".txt" instead of "txt" please. – Distjubo May 08 '15 at 11:35

Distjubo · Answer 3 · 2015-04-30T15:46:28.397

1

Use Files.probeContentPath() to get a mime of the file.

edited Apr 30 '15 at 15:46

answered Apr 30 '15 at 15:39

Distjubo

959
6
21

Assuming you mean `Files.probeContentType`, this actually relies on the file extension also...;) – Reimeus Apr 30 '15 at 15:46
Oops, its probeContentPath and not propeContentPath. derp xD – Distjubo Apr 30 '15 at 15:46

score 0 · Answer 4 · answered Apr 30 '15 at 15:43

You can use a FileNameFilter to do that work for you. Your code could look like this:

    File[] files = dir.listFiles(new FilenameFilter() {         
        @Override
        public boolean accept(File dir, String name) {
            if (name.toLowerCase().endsWith(".txt")) return true;
            return false;
        }
    });

Then you know that files contains only files that end with .txt, or whatever other conditions you need.

score 0 · Answer 5 · edited May 23 '17 at 10:29

0

I like the DirectoryScanner method which uses ant.jar.

DirectoryScanner scanner = new DirectoryScanner();
scanner.setIncludes(new String[]{"**/*.txt"});
scanner.setBasedir("C:\\Files");
scanner.setCaseSensitive(false);
scanner.scan();
String[] files = scanner.getIncludedFiles();

This is from Misha Here. But as you can see there are many ways to do this.

edited May 23 '17 at 10:29

Community

1
1

answered Apr 30 '15 at 15:45

ghg565

422
6
15

score 0 · Answer 6 · answered Apr 30 '15 at 15:52

Write a method that returns all the .txt files in a given directory.

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

public class Data {
         public File[] finder( String dirName){
                File dir = new File(dirName);

                return dir.listFiles(new FilenameFilter() { 
                         public boolean accept(File dir, String filename)
                              { return filename.endsWith(".txt"); }
                } );

            }
        public static void main(String[] args) throws IOException {
            String target_dir = "C:\\Files";
            String textfile;
            File dir = new File(target_dir);
            File[] files = finder(target_dir);

            for (File textfiles : files) {
                if (textfiles.isFile() && textfiles.getName().endsWith("txt")) {

                    BufferedReader inputStream = null;

                    try {
                        inputStream = new BufferedReader(new FileReader(textfiles));
                        String line;

                        while ((line = inputStream.readLine()) != null) {
                            System.out.println(line);
                        }
                    } finally {
                        if (inputStream != null) {
                            inputStream.close();
                        }
                    }
                }
            }
        }
    }

shridhar · Answer 7 · 2022-08-11T08:51:09.397

0

DIR* dir = opendir("."); // to open current dir

entity = readdir(dir);

while(entity != NULL){

    sprintf(filename,"%s", entity->d_name);
    
    len = strlen(filename);

    if(strcmp(filename+len-4,".txt")) {entity = readdir(dir); continue;} 

   // operation to execute.

    entity = readdir(dir);
    
}

//like this also we can do this task

edited Aug 11 '22 at 08:51

answered Aug 11 '22 at 08:48

shridhar

1
2

Answer in C for a Java question. – mikyll98 Aug 15 '22 at 00:29

How can I read only text files in a directory?

7 Answers7