How to find files by extension in Java

If you don’t know how to search files with specific extensions in a directory, then read this page carefully. Here we have shared the easiest ways to search files with specific extensions using Java code.

Method 1:

If you are using > Java 8, you can use Files.walk() to find files with specific extensions. Here is the source code in which we have implemented the Files.walk() method.

Source code:

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class Example {

    public static void main(String[] args) throws IOException {

        Path path = Paths.get("E:\\Java Programs");
        List paths = FindingFile(path, ".zip");
        paths.forEach(y -> System.out.println(y));

    }

    public static List FindingFile(Path path, String extension){

        if (!Files.isDirectory(path)) {
            throw new IllegalArgumentException("Path must be a directory!");
        }

        List result = new ArrayList<>();
        try (Stream walk = Files.walk(path)) {
            result = walk
                    .filter(Files::isRegularFile)
                    .filter(p -> p.getFileName().toString().endsWith(extension))
                    .collect(Collectors.toList());
        } catch(IOException ex){
            System.out.println("Error");
        }
        return result;

    }

}

Output:

run:
E:\Java Programs\.metadata\.mylyn\.tasks.xml.zip
E:\Java Programs\.metadata\.mylyn\repositories.xml.zip
E:\Java Programs\Abdul\Fiverr Front End3.zip
E:\Java Programs\Anattele\Game.zip
E:\Java Programs\Bot (2).zip
E:\Java Programs\Bot.zip
E:\Java Programs\Business Management Tool (2).zip
E:\Java Programs\Business Management Tool.zip
E:\Java Programs\CSVUpdatingProgram.zip
E:\Java Programs\DSA Paper.zip
E:\Java Programs\SDA Theory Bot.zip
BUILD SUCCESSFUL (total time: 2 seconds)

Method 2:

Another way for finding files with specific extensions is to use accept() method of the FilenameFilter interface. We have created a class that is extended from FilenameFilter. In this class, we override the accept() method that returns the file name ending with the extension that the user passes as a parameter.

Source code:


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

public class Example {

    public void DisplayFiles(String folder, String extension) {

        ExtensionFilter filter = new ExtensionFilter(extension);
        File direction = new File(folder);
        String[] list = direction.list(filter);

        for (int i = 0; i < list.length; i++) {
            // printing the elements
            System.out.println(list[i]);
        }

        //If array of string is empty, it will return
        if (list.length == 0) {
            System.out.println("Nothing to show");
            return;
        }

    }

    public static void main(String args[]) {
        String listOfExtension[]={".PNG",".zip",".JPG"};
        String FILE_DIR = "E://Java Programs";
        for(int i=0; i<listOfExtension.length; i++)
        new Example().DisplayFiles(FILE_DIR, listOfExtension[i]);
    }
}

class ExtensionFilter implements FilenameFilter {

    private String ext;

    public ExtensionFilter(String ext) {

        this.ext = ext;
    }

    @Override
    public boolean accept(File dir, String name) {
        // This method return the file name along with the file extension
        return (name.endsWith(ext));
    }
}

Output:


run:
ss.png
Bot (2).zip
Bot.zip
Business Management Tool (2).zip
Business Management Tool.zip
CSVUpdatingProgram.zip
DSA Paper.zip
Mail Room Stack.zip
Queues Assignment.zip
SDA Theory Bot.zip
Task.zip
Nothing to show
BUILD SUCCESSFUL (total time: 2 seconds)

References:

Happy Learning 🙂