File	Doc	Category	Size	Date	Package
FileLister.java	API Doc	Example	8303	Mon Sep 22 13:30:30 BST 1997	None

FileLister

• java.lang.Object
  • CloseableFrame

Fields Summary
private List	list
private TextField	details
private Panel	buttons
private Button	up
private Button	close
private File	currentDir
private FilenameFilter	filter
private String[]	files
private DateFormat	dateFormatter

Constructors Summary

public FileLister(String directory, FilenameFilter filter) Constructor: create the GUI, and list the initial directory. super("File Lister"); // Create the window this.filter = filter; // Save the filter, if any list = new List(12, false); // Set up the list list.setFont(new Font("MonoSpaced", Font.PLAIN, 14)); list.addActionListener(this); list.addItemListener(this); details = new TextField(); // Set up the details area details.setFont(new Font("MonoSpaced", Font.PLAIN, 12)); details.setEditable(false); buttons = new Panel(); // Set up the button box buttons.setLayout(new FlowLayout(FlowLayout.RIGHT, 15, 5)); buttons.setFont(new Font("SansSerif", Font.BOLD, 14)); up = new Button("Up a Directory"); // Set up the two buttons close = new Button("Close"); up.addActionListener(this); close.addActionListener(this); buttons.add(up); // Add buttons to button box buttons.add(close); this.add(list, "Center"); // Add stuff to the window this.add(details, "North"); this.add(buttons, "South"); this.setSize(500, 350); listDirectory(directory); // And now list the initial directory.

Methods Summary
public void	actionPerformed(java.awt.event.ActionEvent e) This ActionListener method is invoked when the user double-clicks on an entry or clicks on one of the buttons. If they double-click on a file, create a FileViewer to display that file. If they double-click on a directory, call the listDirectory() method to display that directory if (e.getSource() == close) this.dispose(); else if (e.getSource() == up) { up(); } else if (e.getSource() == list) { // Double click on an item int i = list.getSelectedIndex(); // Check which item if (i == 0) up(); // Handle first Up To Parent item else { // Otherwise, get filename String name = files[i-1]; File f = new File(currentDir, name); // Convert to a File String fullname = f.getAbsolutePath(); if (f.isDirectory()) listDirectory(fullname); // List a directory else new FileViewer(fullname).show(); // or display a file } }
public void	itemStateChanged(java.awt.event.ItemEvent e) This ItemListener method uses various File methods to obtain information about a file or directory. Then it displays that info in the details box. int i = list.getSelectedIndex() - 1; // minus 1 for Up To Parent entry if (i < 0) return; String filename = files[i]; // Get the selected entry File f = new File(currentDir, filename); // Convert to a File if (!f.exists()) // Confirm that it exists throw new IllegalArgumentException("FileLister: " + "no such file or directory"); // Get the details about the file or directory, concatenate to a string String info = filename; if (f.isDirectory()) info += File.separator; info += " " + f.length() + " bytes "; info += dateFormatter.format(new java.util.Date(f.lastModified())); if (f.canRead()) info += " Read"; if (f.canWrite()) info += " Write"; // And display the details string details.setText(info);
public void	listDirectory(java.lang.String directory) This method uses the list() method to get all entries in a directory and then displays them in the List component. // Convert the string to a File object, and check that the dir exists File dir = new File(directory); if (!dir.isDirectory()) throw new IllegalArgumentException("FileLister: no such directory"); // Get the (filtered) directory entries files = dir.list(filter); // And sort them. Sorter.sort(files); // Remove any old entries in the list, and add the new ones list.removeAll(); list.addItem("[Up to Parent Directory]"); // A special case entry for(int i = 0; i < files.length; i++) list.addItem(files[i]); // Display directory name in window titlebar and in the details box this.setTitle(directory); details.setText(directory); // Remember this directory for later. currentDir = dir;
public static void	main(java.lang.String[] args) A main() method so FileLister can be run standalone. Parse command line arguments and create the FileLister object. If an extension is specified, create a FilenameFilter for it. If no directory is specified, use the current directory. FileLister f; FilenameFilter filter = null; // The filter, if any String directory = null; // The specified dir, or the current dir // Loop through args array, parsing arguments for(int i = 0; i < args.length; i++) { if (args[i].equals("-e")) { if (++i >= args.length) usage(); final String suffix = args[i]; // final for use in anon. class below // This class is a simple FilenameFilter. It defines the // accept() method required to determine whether a specified // file should be listed. A file will be listed if its name // ends with the specified extension, or if it is a directory. filter = new FilenameFilter() { public boolean accept(File dir, String name) { if (name.endsWith(suffix)) return true; else return (new File(dir, name)).isDirectory(); } }; } else { if (directory != null) usage(); // If dir already specified, fail. else directory = args[i]; } } // if no directory specified, use the current directoy if (directory == null) directory = System.getProperty("user.dir"); // Create the FileLister object, with directory and filter specified. f = new FileLister(directory, filter); // Arrange for the application to exit when the FileLister window closes f.addWindowListener(new WindowAdapter() { public void windowClosed(WindowEvent e) { System.exit(0); } }); // And pop up the FileLister. f.show();
protected void	up() A convenience method to display the contents of the parent directory String parent = currentDir.getParent(); if (parent == null) return; listDirectory(parent);
public static void	usage() A convenience method used by main() System.out.println("Usage: java FileLister [directory_name] " + "[-e file_extension]"); System.exit(0);