Question

I need to create a component as shown in the figure – a tree with directory selection via checkbox. Is there is a built in component for this (like others such as JFileChooser etc.)?

Answer 1

Is there is a built in component for this (like others such as JFileChooser etc.)?

No, not a ready-made component for that specific purpose. OTOH it is not very difficult to throw something together using a JTree.

You might start with the code shown on https://stackoverflow.com/questions/6182110/file-browser-gui. It uses a tree.

Nodes with check-boxes

..a tree with directory selection via checkbox.

The selection via. checkbox makes it a bit more tricky. Here are two possible approaches.

Use a renderer

This allows multi-selection in the same way that multiple nodes might be selected in a standard tree, but swaps the BG selection color for a checked check-box.

It then becomes very easy to use the inbuilt methods such as JTree.getSelectionPaths() and handles multi/single selection with a single method call.

import java.awt.*;
import javax.swing.*;
import javax.swing.tree.*;
import java.io.*;

class TreeWithCheck {

    public static Component getTree(int selectionMode) {
        JTree tree = new JTree();
        tree.getSelectionModel().setSelectionMode(selectionMode);
        tree.setVisibleRowCount(8);
        SelectableTreeCellRenderer renderer =
            new SelectableTreeCellRenderer();
        tree.setCellRenderer(renderer);
        JScrollPane scroll = new JScrollPane(tree);
        Dimension d = scroll.getPreferredSize();
        scroll.setPreferredSize(
            new Dimension((int)d.getWidth()*2, (int)d.getHeight()));

        return scroll;
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JPanel trees = new JPanel(new GridLayout(0,2,5,5));

                trees.add(
                    getTree(TreeSelectionModel.SINGLE_TREE_SELECTION));
                trees.add(
                    getTree(TreeSelectionModel.DISCONTIGUOUS_TREE_SELECTION));

                JOptionPane.showMessageDialog(null, trees);
            }
        });
    }
}

class SelectableTreeCellRenderer extends DefaultTreeCellRenderer {

    private JCheckBox selected;
    private JPanel renderComponent;

    public SelectableTreeCellRenderer() {
        selected = new JCheckBox();
        renderComponent = new JPanel(new BorderLayout());
        renderComponent.add(selected,BorderLayout.WEST);

        selected.setOpaque(false);
        renderComponent.setOpaque(false);
    }

    public Component getTreeCellRendererComponent(
        JTree tree,
        Object value,
        boolean sel,
        boolean expanded,
        boolean leaf,
        int row,
        boolean hasFocus) {

        Component c = super.getTreeCellRendererComponent(
            tree,
            value,
            false, // we pass 'false' rather than 'sel'
            expanded,
            leaf,
            row,
            hasFocus);

        selected.setSelected(sel);
        renderComponent.add(c,BorderLayout.CENTER);

        return renderComponent;
    }
}

Define a custom object

One way you might approach it is to put custom objects into the tree, rather than File instances. The custom object might be called a SelectableDirectory and have a File directory & boolean selected as the attributes. Something like:

public class SelectableDirectory {

    private File directory;
    private boolean selected;
    // getters and setters, constructor..
}

Use a custom renderer for the tree that returns a JPanel containing a checkbox in BorderLayout.WEST and a JLabel with icon and directory name in the CENTER.