How to filter file type in FileDialog?

Question

I am using FileDialog for saving and loading in a Java program.

How can I filter the dropdown list to specify the file type as "JPG" or "JPEG" etc. ?

I have tried the following code, but it seems to have no effect.

Are there any other ways of doing this ?

public void actionPerformed(ActionEvent e) {
            FileDialog saveFileDialog = new FileDialog(new Frame(), "Save", FileDialog.SAVE);

            saveFileDialog.setFilenameFilter(new FilenameFilter(){
                @Override
                public boolean accept(File dir, String name) {
                    return name.endsWith(".jpg") || name.endsWith(".jpeg");
                }
            });
            saveFileDialog.setFile("Untitled.jpg");
            saveFileDialog.setVisible(true);
        }

Answer 1

I've always used JFileChooser instead of FileDialog. You can then add multiple ChoosableFileFilters for the various types your program will support this way:

File myFilename;
chooser = new JFileChooser();
chooser.addChoosableFileFilter(new OpenFileFilter("jpeg","Photo in JPEG format") );
chooser.addChoosableFileFilter(new OpenFileFilter("jpg","Photo in JPEG format") );
chooser.addChoosableFileFilter(new OpenFileFilter("png","PNG image") );
chooser.addChoosableFileFilter(new OpenFileFilter("svg","Scalable Vector Graphic") );
int returnVal = chooser.showSaveDialog(mainWindow);
if (returnVal == JFileChooser.APPROVE_OPTION) {
     myFilename = chooser.getSelectedFile();
     //do something with the file
}

Below is my implementation of a FileFilter.

/**
 * This class defines which file types are displayed (by default) by the JFileChooser and what file
 * types appear in the drop down menu in the file dialog.
 * You could add more than one file type to the open file dialog by creating multiple instances of this 
 * class and then repeatedly calling addFileFilter.
 * @author LaSpina
 */

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

public class OpenFileFilter extends FileFilter {

    String description = "";
    String fileExt = "";

    public OpenFileFilter(String extension) {
        fileExt = extension;
    }

    public OpenFileFilter(String extension, String typeDescription) {
        fileExt = extension;
        this.description = typeDescription;
    }

    @Override
    public boolean accept(File f) {
        if (f.isDirectory())
            return true;
        return (f.getName().toLowerCase().endsWith(fileExt));
    }

    @Override
    public String getDescription() {
        return description;
    }
}

Answer 2

The answer is simple. You can use

 saveFileDialog.setFile("*.jpg;*.jpeg");

No need to use setFilenameFilter method. You can add as many file type as you which.

Solving of this problem can be found in huxhorn' s comment in Bug ID: 4031440 FileDialog doesn't call FilenameFilter.accept().

public void actionPerformed(ActionEvent e) {
            FileDialog saveFileDialog = new FileDialog(new Frame(), "Save", FileDialog.SAVE);
            saveFileDialog.setFile("*.jpg;*.jpeg");
            saveFileDialog.setVisible(true);
        }

Answer 3

It doesn't work for me either. Filename filters do not function in Sun's reference implementation for Microsoft Windows.

Instead, you could try the below code. You should also remove the setFilenameFilter part:

saveFileDialog.setFile("*.jpg");

Answer 4

Starting with Java 8 you can a Lambda expression:

fileDialog.setFilenameFilter((File dir, String name) -> name.endsWith(".html"));