DirTree

DirTree is a component that gives you a read-only view onto a file system, with the optional ability to "lock" the view (chroot-style) to a specific directory.

Right-clicking on the tree will allow you to lock the tree to the given node:

This has an effect similar to chroot, in that the DirTree component now views that directory as the root of the filesystem, and can only see directories underneath it:

You can then right-click again to unlock the tree.

Locking and unlocking can be allowed or disallowed programmatically:

// Create a DirTree for my home directory and disallow locking/unlocking:
DirTree myDirTree = DirTree.createDirTree(new File("/home/scorbett"));
myDirTree.setAllowLock(false);
myDirTree.setAllowUnlock(false);

Detecting and responding to events

Of course, displaying a read-only view of a file system is not terribly useful without the ability to detect user selection events:

myDirTree.addDirTreeListener(new DirTreeListener() {
    @Override
    public boolean selectionWillChange(DirTree source, File newSelectedDir) {
        return true; // Allow the selection to change
    }
    
    @Override
    public void selectionChanged(DirTree source, File selectedDir) {
        // The selection has changed
    }

    @Override
    public void showHiddenFilesChanged(DirTree source, boolean showHiddenFiles) {
        // The "show hidden files" setting has changed
    }
    
    @Override
    public void treeLocked(DirTree source, File lockDir) {
        // Tree has been locked to lockDir
    }

    @Override
    public void treeUnlocked(DirTree source) {
        // Tree has been unlocked
    }
    
    @Override
    public void fileDoubleClicked(DirTree source, File file) {
        // A file was double-clicked in the tree
    }
});

Now you can respond to selection changes by, for example, displaying a list of files in the current directory in some other part of your application UI.

Confirming selection changes

Perhaps there are unsaved changes in your application related to the currently selected directory. In that case, you may wish to show a confirmation dialog before allowing the user to change the selection. How can we do this? We can use the selectionWillChange event to intercept selection changes and show a confirmation dialog:

// Inside our DirTreeListener implementation:
@Override
public boolean selectionWillChange(DirTree source, File newSelectedDir) {
    int result = JOptionPane.showConfirmDialog(
        null,
        "You have unsaved changes! Really change directories?",
        "Confirm selection change",
        JOptionPane.YES_NO_OPTION
    );
    return result == JOptionPane.YES_OPTION;
}

If the user selects "No", then the selection change is canceled and the DirTree remains on the previously selected directory.

Programmatic selection

You can also programmatically lock the DirTree to any particular directory, regardless of whether locking is enabled or disabled for the user:

myDirTree.lock(new File("/some/other/dir"));

And you can select a particular directory, and cause the DirTree to scroll if necessary so that it is visible in the view:

myDirTree.selectAndScrollTo(new File("/some/nested/dir/somewhere/else"));

New in 2.8! Showing files in the tree

In swing-extras releases prior to 2.8, the DirTree component only showed directories. This is still the default behavior in 2.8, to maintain backward compatibility, but now you have the option to show files in the tree as well, if you wish:

// Show files in the tree (by default, only directories are shown):
myDirTree.setShowFiles(true);

// Set an optional FileFilter to control which files are shown (by default, all files are shown):
myDirTree.setFileFilter(file -> file.isDirectory() || file.getName().endsWith(".txt"));

A new fileDoubleClicked event has also been added to the DirTreeListener interface, so that you can respond to double-clicks on files in the tree:

@Override
public void fileDoubleClicked(DirTree source, File file) {
    // A file was double-clicked in the tree
    // For example, we could open the file in an editor:
    openFileInEditor(file);
}

Showing or hiding "hidden" files

Exactly what constitutes a "hidden" file is platform-dependent. For example, on Linux-based systems, a hidden file is any file or directory whose name begins with a dot (.). With DirTree, you can opt to show these hidden directories, either programmatically, or via the popup menu:

// Let's hide hidden files/dirs (by default, they are shown):
myDirTree.setShowHidden(false);

Note that "show hidden" here applies to both hidden files and hidden directories.

Real-world example

For a real-world usage of the DirTree component, I refer you to my own imageviewer application: