Swap Tree Nodes

[Abraham Khalil]

Want to swap tree nodes.
Please run the sample below where I need the help in the print
statements.

Thanks

==========================================================================

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


public class TreeExample extends JFrame implements ActionListener {
private static final int WIDTH = 640;
private static final int HEIGHT = 480;

private static final String MOVE_UP_ACTION = "move_up_action";
private static final String MOVE_DOWN_ACTION = "move_down_action";


private JTree tree = null;


public TreeExample() {
super("Wizard test");

Container container = getContentPane();
container.setLayout(new BorderLayout());


int locX = (Toolkit.getDefaultToolkit().getScreenSize().width -
WIDTH) / 2;
int locY = (Toolkit.getDefaultToolkit().getScreenSize().height -
HEIGHT) / 2;
setBounds(locX, locY, WIDTH, HEIGHT);

addWindowListener(new WindowAdapter() {
public void windowClosing( WindowEvent e ) {
System.exit(0);
}
});


JPanel buttonsPanel = new JPanel();
buttonsPanel.setLayout(new GridLayout(2, 1, 0, 8));

final JButton moveUpButton = new JButton("Move Up");
moveUpButton.setFont(moveUpButton.getFont().deriveFont(Font.PLAIN));
moveUpButton.setMnemonic('U');
moveUpButton.setActionCommand(MOVE_UP_ACTION);
moveUpButton.setEnabled(false);
moveUpButton.addActionListener(this);

final JButton moveDownButton = new JButton("Move Down");
moveDownButton.setFont(moveUpButton.getFont().deriveFont(Font.PLAIN));
moveDownButton.setMnemonic('D');
moveDownButton.setActionCommand(MOVE_DOWN_ACTION);
moveDownButton.setEnabled(false);
moveDownButton.addActionListener(this);

buttonsPanel.add(moveUpButton);
buttonsPanel.add(moveDownButton);


DefaultMutableTreeNode root = new
DefaultMutableTreeNode("Sample");

DefaultMutableTreeNode colors = new
DefaultMutableTreeNode("colors");
colors.add(new DefaultMutableTreeNode("blue"));
colors.add(new DefaultMutableTreeNode("violet"));
colors.add(new DefaultMutableTreeNode("red"));
colors.add(new DefaultMutableTreeNode("yellow"));

DefaultMutableTreeNode sports = new
DefaultMutableTreeNode("sports");
sports.add(new DefaultMutableTreeNode("basketball"));
sports.add(new DefaultMutableTreeNode("soccer"));
sports.add(new DefaultMutableTreeNode("football"));
sports.add(new DefaultMutableTreeNode("hockey"));

DefaultMutableTreeNode programs = new
DefaultMutableTreeNode("programs");
programs.add(new DefaultMutableTreeNode("Java"));
programs.add(new DefaultMutableTreeNode("ASP .Net"));
programs.add(new DefaultMutableTreeNode("C"));
programs.add(new DefaultMutableTreeNode("Perl"));


root.add(colors);
root.add(sports);
root.add(programs);

tree = new JTree(root);
tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);

tree.addTreeSelectionListener(new TreeSelectionListener() {
public void valueChanged(TreeSelectionEvent e) {
Object nodeInfo = tree.getLastSelectedPathComponent();

if (nodeInfo == null) return;

DefaultMutableTreeNode treeSelectNode =
(DefaultMutableTreeNode) nodeInfo;
DefaultMutableTreeNode parentNode =
(DefaultMutableTreeNode) treeSelectNode.getParent();

if (parentNode != null) {
moveUpButton.setEnabled(parentNode.getChildCount() > 1
&&

!parentNode.getFirstChild().equals(treeSelectNode));

moveDownButton.setEnabled(parentNode.getChildCount() >
1 &&

!parentNode.getLastChild().equals(treeSelectNode));
}
else {
moveDownButton.setEnabled(false);
moveUpButton.setEnabled(false);
}
}
});



JScrollPane scrollPane = new JScrollPane(tree);

JPanel mainPanel = new JPanel();
mainPanel.setLayout(new GridBagLayout());

constrain( mainPanel, scrollPane,
GridBagConstraints.BOTH,
GridBagConstraints.NORTHWEST,
0, 0, 1, 1, 1.0, 1.0, new Insets(10, 10, 10, 10));

constrain( mainPanel, buttonsPanel,
GridBagConstraints.NONE,
GridBagConstraints.NORTHWEST,
1, 0, 1, 1, 0.0, 0.0, new Insets(10, 0, 10, 10));


container.add(mainPanel, BorderLayout.NORTH);
}



public void constrain( Container container, Component component,
int fill, int anchor,
int gx, int gy, int gw, int gh, double wx,
double wy ) {

GridBagConstraints c = new GridBagConstraints();

c.fill = fill;
c.anchor = anchor;
c.gridx = gx;
c.gridy = gy;
c.gridwidth = gw;
c.gridheight = gh;
c.weightx = wx;
c.weighty = wy;

( (GridBagLayout) container.getLayout() ).setConstraints(
component, c );

container.add( component );
}


public void constrain( Container container, Component component,
int fill, int anchor,
int gx, int gy, int gw, int gh,
double wx, double wy, Insets inset ) {
GridBagConstraints c = new GridBagConstraints();

c.fill = fill;
c.anchor = anchor;
c.gridx = gx;
c.gridy = gy;
c.gridwidth = gw;
c.gridheight = gh;
c.weightx = wx;
c.weighty = wy;
c.insets = inset;

( (GridBagLayout) container.getLayout() ).setConstraints(
component, c );

container.add( component );
}


public void actionPerformed(ActionEvent e) {
String action = e.getActionCommand();
Object nodeInfo = tree.getLastSelectedPathComponent();

if (action != null && nodeInfo != null) {
DefaultMutableTreeNode treeSelectNode =
(DefaultMutableTreeNode) nodeInfo;
DefaultMutableTreeNode parentNode = (DefaultMutableTreeNode)
treeSelectNode.getParent();

if (parentNode != null) {
int treeSelectIndex = parentNode.getIndex(treeSelectNode);

if (action.equals(MOVE_UP_ACTION)) {
DefaultMutableTreeNode nextNodeUp =
(DefaultMutableTreeNode) parentNode.getChildAt(treeSelectIndex - 1);
System.out.println("Want to swap " + treeSelectNode + "
with " + nextNodeUp);
}

if (action.equals(MOVE_DOWN_ACTION)) {
DefaultMutableTreeNode nextNodeDown =
(DefaultMutableTreeNode) parentNode.getChildAt(treeSelectIndex + 1);
System.out.println("Want to swap " + treeSelectNode + "
with " + nextNodeDown);
}
}
}
}


public static void main(String args[]) {
new TreeExample().setVisible(true);
}
}

 

[Christian Kaufhold]

Want to swap tree nodes.
Please run the sample below where I need the help in the print
statements.

Please do not multipost!



Christian

 

[soft-eng]

if (action.equals(MOVE_UP_ACTION)) {
DefaultMutableTreeNode nextNodeUp =
(DefaultMutableTreeNode) parentNode.getChildAt(treeSelectIndex - 1);
System.out.println("Want to swap " + treeSelectNode + "
with " + nextNodeUp);
}

Instead of a swap, you actually need to do something like:

parentNode.insert(treeSelectNode, treeSelectIndex - 1 );

which is enough, as it will move everything else down 1 (and
will get a swap in the process, too.)

A similar technique can be used for for moving down: insert
it one lower.

But note that you have to call

((DefaultTreeModel)tree.getModel()).nodeStructureChanged(parentNode);

before your changes will be posted to the tree. (You can
actually provide better info than "nodeStructureChanged",
see documentation. Structure-change kind of covers
everything, in a simplistic way.)

 

[Abraham Khalil]

Thanks a lot. Its a smart idea.
Have you ever worked on JTreeTable? Trying to swap the nodes using JTreeTable
and not sure what events to fire with...