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  1. POMultiple Components in a JTree Node Renderer & Node Editor
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    <p>I am attempting to create a JTree where a node has several components: a JPanel that holds a JCheckBox, followed by a JLabel, then a JComboBox. I have attached the code at the bottom if one wishes to run it. Fortunately the JTree correctly renders the components. However when I click on the JComboBox, the node disappears; if I click on the JCheckBox, it works fine. It seems that I am doing something wrong with how the TreeCellEditor is being set up. How could I resolve this issue? Am I going beyond the capabilities of JTree?</p> <p>Here's a quick overview of the code I have posted below.</p> <ul> <li>The class <code>EntityListDialog</code> merely creates the user interface. It is not useful to understand it other than the <code>createTree</code> method.</li> <li><code>Node</code> is the data structure that holds information about each node in the JTree. All <code>Node</code>s have a <code>name</code>, but <code>samples</code> may be null or an empty array. This should be evident by looking at <code>EntityListDialog</code>'s <code>createTree</code> method. The <code>name</code> is used as the text of the JCheckBox. If <code>samples</code> is non-empty, it is used as the contents of the JCheckBox.</li> <li><code>NodeWithSamplesRenderer</code> renders <code>Node</code>s whose <code>sample</code>s are non-empty. It creates the complicated user interface with the JPanel consisting of the JCheckBox and the JComboBox.</li> <li><code>NodeWithoutSamplesRenderer</code> creates just a JCheckBox when <code>samples</code> is empty.</li> <li><code>RendererDispatcher</code> decides whether to use a <code>NodeWithSamplesRenderer</code> or a <code>NodeWithoutSamplesRenderer</code>. This entirely depends on whether <code>Node</code> has a non-empty <code>samples</code> member or not. It essentially functions as a means for the <code>NodeWith</code>*<code>SamplesRenderer</code> to plug into the JTree.</li> </ul> <p>Code listing:</p> <pre><code>import java.awt.*; import java.awt.event.*; import java.util.*; import javax.swing.*; import javax.swing.tree.*; public class EntityListDialog { final JDialog dialog; final JTree entitiesTree; public EntityListDialog() { dialog = new JDialog((Frame) null, "Test"); entitiesTree = createTree(); JScrollPane entitiesTreeScrollPane = new JScrollPane(entitiesTree); JCheckBox pathwaysCheckBox = new JCheckBox("Do additional searches"); JButton sendButton = new JButton("Send"); JButton cancelButton = new JButton("Cancel"); JButton selectAllButton = new JButton("All"); JButton deselectAllButton = new JButton("None"); dialog.getContentPane().setLayout(new GridBagLayout()); GridBagConstraints c = new GridBagConstraints(); JPanel selectPanel = new JPanel(new FlowLayout(FlowLayout.LEFT)); selectPanel.add(new JLabel("Select: ")); selectPanel.add(selectAllButton); selectPanel.add(deselectAllButton); c.gridx = 0; c.gridy = 0; c.weightx = 1.0; c.weighty = 0.0; c.fill = GridBagConstraints.HORIZONTAL; dialog.getContentPane().add(selectPanel, c); c.gridx = 0; c.gridy = 1; c.weightx = 1.0; c.weighty = 1.0; c.fill = GridBagConstraints.BOTH; c.insets = new Insets(0, 5, 0, 5); dialog.getContentPane().add(entitiesTreeScrollPane, c); c.gridx = 0; c.gridy = 2; c.weightx = 1.0; c.weighty = 0.0; c.insets = new Insets(0, 0, 0, 0); c.fill = GridBagConstraints.HORIZONTAL; dialog.getContentPane().add(pathwaysCheckBox, c); JPanel buttonsPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT)); buttonsPanel.add(sendButton); buttonsPanel.add(cancelButton); c.gridx = 0; c.gridy = 3; c.weightx = 1.0; c.weighty = 0.0; c.fill = GridBagConstraints.HORIZONTAL; dialog.getContentPane().add(buttonsPanel, c); dialog.pack(); dialog.setVisible(true); } public static void main(String[] args) { EntityListDialog dialog = new EntityListDialog(); } private static JTree createTree() { DefaultMutableTreeNode root = new DefaultMutableTreeNode( new Node("All Entities")); root.add(new DefaultMutableTreeNode( new Node("Entity 1", "Sample A", "Sample B", "Sample C"))); root.add(new DefaultMutableTreeNode( new Node("Entity 2", "Sample D", "Sample E", "Sample F"))); root.add(new DefaultMutableTreeNode( new Node("Entity 3", "Sample G", "Sample H", "Sample I"))); JTree tree = new JTree(root); RendererDispatcher rendererDispatcher = new RendererDispatcher(tree); tree.setCellRenderer(rendererDispatcher); tree.setCellEditor(rendererDispatcher); tree.setEditable(true); return tree; } } class Node { final String name; final String[] samples; boolean selected; int selectedSampleIndex; public Node(String name, String... samples) { this.name = name; this.selected = false; this.samples = samples; if (samples == null) { this.selectedSampleIndex = -1; } else { this.selectedSampleIndex = 0; } } public boolean isSelected() { return selected; } public void setSelected(boolean selected) { this.selected = selected; } public String toString() { return name; } public int getSelectedSampleIndex() { return selectedSampleIndex; } public void setSelectedSampleIndex(int selectedSampleIndex) { this.selectedSampleIndex = selectedSampleIndex; } public String[] getSamples() { return samples; } } interface Renderer { public void setForeground(final Color foreground); public void setBackground(final Color background); public void setFont(final Font font); public void setEnabled(final boolean enabled); public Component getComponent(); public Object getContents(); } class NodeWithSamplesRenderer implements Renderer { final DefaultComboBoxModel comboBoxModel = new DefaultComboBoxModel(); final JPanel panel = new JPanel(); final JCheckBox checkBox = new JCheckBox(); final JLabel label = new JLabel(" Samples: "); final JComboBox comboBox = new JComboBox(comboBoxModel); final JComponent components[] = {panel, checkBox, comboBox, label}; public NodeWithSamplesRenderer() { Boolean drawFocus = (Boolean) UIManager.get("Tree.drawsFocusBorderAroundIcon"); if (drawFocus != null) { checkBox.setFocusPainted(drawFocus.booleanValue()); } for (int i = 0; i &lt; components.length; i++) { components[i].setOpaque(true); } panel.add(checkBox); panel.add(label); panel.add(comboBox); } public void setForeground(final Color foreground) { for (int i = 0; i &lt; components.length; i++) { components[i].setForeground(foreground); } } public void setBackground(final Color background) { for (int i = 0; i &lt; components.length; i++) { components[i].setBackground(background); } } public void setFont(final Font font) { for (int i = 0; i &lt; components.length; i++) { components[i].setFont(font); } } public void setEnabled(final boolean enabled) { for (int i = 0; i &lt; components.length; i++) { components[i].setEnabled(enabled); } } public void setContents(Node node) { checkBox.setText(node.toString()); comboBoxModel.removeAllElements(); for (int i = 0; i &lt; node.getSamples().length; i++) { comboBoxModel.addElement(node.getSamples()[i]); } } public Object getContents() { String title = checkBox.getText(); String[] samples = new String[comboBoxModel.getSize()]; for (int i = 0; i &lt; comboBoxModel.getSize(); i++) { samples[i] = comboBoxModel.getElementAt(i).toString(); } Node node = new Node(title, samples); node.setSelected(checkBox.isSelected()); node.setSelectedSampleIndex(comboBoxModel.getIndexOf( comboBoxModel.getSelectedItem())); return node; } public Component getComponent() { return panel; } } class NodeWithoutSamplesRenderer implements Renderer { final JCheckBox checkBox = new JCheckBox(); public NodeWithoutSamplesRenderer() { Boolean drawFocus = (Boolean) UIManager.get("Tree.drawsFocusBorderAroundIcon"); if (drawFocus != null) { checkBox.setFocusPainted(drawFocus.booleanValue()); } } public void setForeground(final Color foreground) { checkBox.setForeground(foreground); } public void setBackground(final Color background) { checkBox.setBackground(background); } public void setFont(final Font font) { checkBox.setFont(font); } public void setEnabled(final boolean enabled) { checkBox.setEnabled(enabled); } public void setContents(Node node) { checkBox.setText(node.toString()); } public Object getContents() { String title = checkBox.getText(); Node node = new Node(title); node.setSelected(checkBox.isSelected()); return node; } public Component getComponent() { return checkBox; } } class NoNodeRenderer implements Renderer { final JLabel label = new JLabel(); public void setForeground(final Color foreground) { label.setForeground(foreground); } public void setBackground(final Color background) { label.setBackground(background); } public void setFont(final Font font) { label.setFont(font); } public void setEnabled(final boolean enabled) { label.setEnabled(enabled); } public void setContents(String text) { label.setText(text); } public Object getContents() { return label.getText(); } public Component getComponent() { return label; } } class RendererDispatcher extends AbstractCellEditor implements TreeCellRenderer, TreeCellEditor { final static Color selectionForeground = UIManager.getColor("Tree.selectionForeground"); final static Color selectionBackground = UIManager.getColor("Tree.selectionBackground"); final static Color textForeground = UIManager.getColor("Tree.textForeground"); final static Color textBackground = UIManager.getColor("Tree.textBackground"); final JTree tree; final NodeWithSamplesRenderer nodeWithSamplesRenderer = new NodeWithSamplesRenderer(); final NodeWithoutSamplesRenderer nodeWithoutSamplesRenderer = new NodeWithoutSamplesRenderer(); final NoNodeRenderer noNodeRenderer = new NoNodeRenderer(); final Renderer[] renderers = { nodeWithSamplesRenderer, nodeWithoutSamplesRenderer, noNodeRenderer }; Renderer renderer = null; public RendererDispatcher(JTree tree) { this.tree = tree; Font font = UIManager.getFont("Tree.font"); if (font != null) { for (int i = 0; i &lt; renderers.length; i++) { renderers[i].setFont(font); } } } public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus) { final Node node = extractNode(value); if (node == null) { renderer = noNodeRenderer; noNodeRenderer.setContents(tree.convertValueToText( value, selected, expanded, leaf, row, false)); } else { if (node.getSamples() == null || node.getSamples().length == 0) { renderer = nodeWithoutSamplesRenderer; nodeWithoutSamplesRenderer.setContents(node); } else { renderer = nodeWithSamplesRenderer; nodeWithSamplesRenderer.setContents(node); } } renderer.setEnabled(tree.isEnabled()); if (selected) { renderer.setForeground(selectionForeground); renderer.setBackground(selectionBackground); } else { renderer.setForeground(textForeground); renderer.setBackground(textBackground); } renderer.getComponent().repaint(); renderer.getComponent().invalidate(); renderer.getComponent().validate(); return renderer.getComponent(); } public Component getTreeCellEditorComponent( JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row) { return getTreeCellRendererComponent( tree, value, true, expanded, leaf, row, true); } public Object getCellEditorValue() { return renderer.getContents(); } public boolean isCellEditable(final EventObject event) { if (!(event instanceof MouseEvent)) { return false; } final MouseEvent mouseEvent = (MouseEvent) event; final TreePath path = tree.getPathForLocation( mouseEvent.getX(), mouseEvent.getY()); if (path == null) { return false; } Object node = path.getLastPathComponent(); if (node == null || (!(node instanceof DefaultMutableTreeNode))) { return false; } DefaultMutableTreeNode treeNode = (DefaultMutableTreeNode) node; Object userObject = treeNode.getUserObject(); return (userObject instanceof Node); } private static Node extractNode(Object value) { if ((value != null) &amp;&amp; (value instanceof DefaultMutableTreeNode)) { DefaultMutableTreeNode node = (DefaultMutableTreeNode) value; Object userObject = node.getUserObject(); if ((userObject != null) &amp;&amp; (userObject instanceof Node)) { return (Node) userObject; } } return null; } } </code></pre>
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