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Message:
Need help with FileFilter
Posted by Thi on November 28, 2001 at 3:15 PM
Hello, I would like to restrict files shown in a file dialog. I've tried to do this by implementing the FileFilter interface, exactly shown in the Core Java book in Chapter 9 under File Dialogs. However, I'm getting an error stating that FileFilter must be an interface. Can someone look at my code and tell me what I have done wrong? Or, can someone show me another way to filter files? Here is my code, which creates a Frame that contains two buttons--one for an open dialog box and the other for a save dialog box: import java.io.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.filechooser.*;
import javax.swing.filechooser.FileFilter; public class FileChooserDemo extends JFrame {
static private final String newline = "\n";
//This is where the compiler says FileFilter must be an
//interface
class TxtFilter implements javax.swing.filechooser.FileFilter
{
public boolean accept(File f)
{
return f.getName().toLowerCase().endsWith(".txt") || f.isDirectory();
}
public String getDescription()
{
return "Text file";
}
}
public FileChooserDemo() {
super("FileChooserDemo");
//Create the log first, because the action listeners
//need to refer to it.
final JTextArea log = new JTextArea(5,20);
log.setMargin(new Insets(5,5,5,5));
log.setEditable(false);
JScrollPane logScrollPane = new JScrollPane(log); //Create a file chooser
final JFileChooser fc = new JFileChooser();
fc.setCurrentDirectory(new File("."));
fc.setFileFilter(new TxtFilter()); //sets the filter to .txt files //Create the open button
JButton openButton = new JButton("Open a File...");
openButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int returnVal = fc.showOpenDialog(FileChooserDemo.this); if (returnVal == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
//this is where a real application would open the file.
log.append("Opening: " + file.getName() + "." + newline);
} else {
log.append("Open command cancelled by user." + newline);
}
}
}); //Create the save button
JButton saveButton = new JButton("Save a File...");
saveButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int returnVal = fc.showSaveDialog(FileChooserDemo.this); if (returnVal == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
//this is where a real application would save the file.
//export the range of events as a .cal file, which can be imported
String filename = file.getName();
log.append("Saving: " + file.getName() + "." + newline);
} else {
log.append("Save command cancelled by user." + newline);
}
}
}); //For layout purposes, put the buttons in a separate panel
JPanel buttonPanel = new JPanel();
buttonPanel.add(openButton);
buttonPanel.add(saveButton); //Explicitly set the focus sequence.
openButton.setNextFocusableComponent(saveButton);
saveButton.setNextFocusableComponent(openButton); //Add the buttons and the log to the frame
Container contentPane = getContentPane();
contentPane.add(buttonPanel, BorderLayout.NORTH);
contentPane.add(logScrollPane, BorderLayout.CENTER);
}
public static void main(String[] args) {
JFrame frame = new FileChooserDemo(); frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
}); frame.pack();
frame.setVisible(true);
}
}
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