In this post, I will guide you how to add file filter for JFileChooser component in Java Swing applications.

You know, it’s very common to have a file extension filter for open/save dialog like the following screenshot:

In Swing, we can do that by using methodaddChoosableFileFilter(FileFilter filter) of the class JFileChooser. 
Create a class that extends FileFilter abstract class and overrides its two methods:

• • boolean accept(File f): returns true if the file f satisfies a filter condition. The condition here is the extension of the file.
  • String getDescription(): returns a description which is displayed in the dialog’s Files of type section.

The following code shows an example of adding a filter for files of type PDF:

JFileChooser fileChooser = new JFileChooser();
fileChooser.addChoosableFileFilter(new FileFilter() {
    public String getDescription() {
        return "PDF Documents (*.pdf)";
    }

    public boolean accept(File f) {
        if (f.isDirectory()) {
            return true;
        } else {
            return f.getName().toLowerCase().endsWith(".pdf");
        }
    }
});

However, what if we need to add several filters, such as for .docx, .xlsx files? Well, one solution is repeating the above code for each file type – but that is not good in terms of code reusability. So, it’s better to create a separate, generalized class for extending the FileFilter abstract class, and parameterize the file extension and description, as shown in the following code:

import java.io.File;
import javax.swing.filechooser.FileFilter;

public class FileTypeFilter extends FileFilter {
    private String extension;
    private String description;

    public FileTypeFilter(String extension, String description) {
        this.extension = extension;
        this.description = description;
    }

    public boolean accept(File file) {
        if (file.isDirectory()) {
            return true;
        }
        return file.getName().endsWith(extension);
    }

    public String getDescription() {
        return description + String.format(" (*%s)", extension);
    }
}

Then we can add several file filters as following:

FileFilter docFilter = new FileTypeFilter(".docx", "Microsoft Word Documents");
FileFilter pdfFilter = new FileTypeFilter(".pdf", "PDF Documents");
FileFilter xlsFilter = new FileTypeFilter(".xlsx", "Microsoft Excel Documents");
fileChooser.addChoosableFileFilter(docFilter);
fileChooser.addChoosableFileFilter(pdfFilter);
fileChooser.addChoosableFileFilter(xlsFilter);

Before Java 6, we have to write the above code manually. Fortunately, since Java 6, Swing adds a new class called FileNameExtensionFilter, which makes adding file filters easier. For example:

fileChooser.addChoosableFileFilter(new FileNameExtensionFilter("PDF Documents", "pdf"));

We also can accumulate multiple extensions together:

fileChooser.addChoosableFileFilter(new FileNameExtensionFilter("Images", "jpg", "png", "gif", "bmp"));

 And following is a sample program that shows an open dialog when the button Browse is clicked, with some filters for: PDF documents, MS Office documents, and Images.

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.filechooser.FileNameExtensionFilter;

/**
 * Demo of file extension filter. Applied since Java 1.6
 * @author www.codejava.net
 *
 */
public class FileExtensionFilterDemo extends JFrame {
    private JButton buttonBrowse;

    public FileExtensionFilterDemo() {
        super("Demo File Type Filter");
        setLayout(new FlowLayout());
        buttonBrowse = new JButton("Browse...");

        buttonBrowse.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                showOpenFileDialog();
            }
        });

        getContentPane().add(buttonBrowse);
        setSize(300, 100);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }

    public static void main(String[] args) {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception e) { }

        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new FileExtensionFilterDemo();
            }
        });
    }

    private void showOpenFileDialog() {
        JFileChooser fileChooser = new JFileChooser();
        fileChooser.setCurrentDirectory(new File(System.getProperty("user.home")));
        fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);

        fileChooser.addChoosableFileFilter(new FileNameExtensionFilter("PDF Documents", "pdf"));
        fileChooser.addChoosableFileFilter(new FileNameExtensionFilter("MS Office Documents", "docx", "xlsx", "pptx"));
        fileChooser.addChoosableFileFilter(new FileNameExtensionFilter("Images", "jpg", "png", "gif", "bmp"));

        fileChooser.setAcceptAllFileFilterUsed(true);

        int result = fileChooser.showOpenDialog(this);

        if (result == JFileChooser.APPROVE_OPTION) {
            File selectedFile = fileChooser.getSelectedFile();
            System.out.println("Selected file: " + selectedFile.getAbsolutePath());
        }
    }
}

 

Related Swing File Chooser Tutorials:

• File picker component in Swing
• Show save file dialog using JFileChooser
• Show simple open file dialog using JFileChooser

 

Other Java Swing Tutorials:

• Java Swing Hello World Tutorial for Beginners Using Text Editor
• JFrame basic tutorial and examples
• JPanel basic tutorial and examples
• JLabel basic tutorial and examples
• JTextField basic tutorial and examples
• JButton basic tutorial and examples