import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.UIManager;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreeSelectionModel;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import java.net.URL;
import java.io.IOException;
import java.awt.Dimension;
import java.awt.GridLayout;
public class TreeDemo extends JPanel
implements TreeSelectionListener {
private JEditorPane htmlPane;
private JTree tree;
private URL helpURL;
private static boolean DEBUG = false;
//Optionally play with line styles. Possible values are
//"Angled" (the default), "Horizontal", and "None".
private static boolean playWithLineStyle = false;
private static String lineStyle = "Horizontal";
//Optionally set the look and feel.
private static boolean useSystemLookAndFeel = false;
public TreeDemo() {
super(new GridLayout(1,0));
//Create the nodes.
DefaultMutableTreeNode top =
new DefaultMutableTreeNode("The Java Series");
createNodes(top);
//Create a tree that allows one selection at a time.
tree = new JTree(top);
tree.getSelectionModel().setSelectionMode
(TreeSelectionModel.SINGLE_TREE_SELECTION);
//Listen for when the selection changes.
tree.addTreeSelectionListener(this);
if (playWithLineStyle) {
System.out.println("line style = " + lineStyle);
tree.putClientProperty("JTree.lineStyle", lineStyle);
}
//Create the scroll pane and add the tree to it.
JScrollPane treeView = new JScrollPane(tree);
//Create the HTML viewing pane.
htmlPane = new JEditorPane();
htmlPane.setEditable(false);
initHelp();
JScrollPane htmlView = new JScrollPane(htmlPane);
//Add the scroll panes to a split pane.
JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
splitPane.setTopComponent(treeView);
splitPane.setBottomComponent(htmlView);
Dimension minimumSize = new Dimension(100, 50);
htmlView.setMinimumSize(minimumSize);
treeView.setMinimumSize(minimumSize);
splitPane.setDividerLocation(100);
splitPane.setPreferredSize(new Dimension(500, 300));
//Add the split pane to this panel.
add(splitPane);
}
/** Required by TreeSelectionListener interface. */
public void valueChanged(TreeSelectionEvent e) {
DefaultMutableTreeNode node = (DefaultMutableTreeNode)
tree.getLastSelectedPathComponent();
if (node == null) return;
Object nodeInfo = node.getUserObject();
if (node.isLeaf()) {
BookInfo book = (BookInfo)nodeInfo;
displayURL(book.bookURL);
if (DEBUG) {
System.out.print(book.bookURL + ": \n ");
}
} else {
displayURL(helpURL);
}
if (DEBUG) {
System.out.println(nodeInfo.toString());
}
}
private class BookInfo {
public String bookName;
public URL bookURL;
public BookInfo(String book, String filename) {
bookName = book;
bookURL = getClass().getResource(filename);
if (bookURL == null) {
System.err.println("Couldn't find file: "
+ filename);
}
}
public String toString() {
return bookName;
}
}
private void initHelp() {
String s = "TreeDemoHelp.html";
helpURL = getClass().getResource(s);
if (helpURL == null) {
System.err.println("Couldn't open help file: " + s);
} else if (DEBUG) {
System.out.println("Help URL is " + helpURL);
}
displayURL(helpURL);
}
private void displayURL(URL url) {
try {
if (url != null) {
htmlPane.setPage(url);
} else { //null url
htmlPane.setText("File Not Found");
if (DEBUG) {
System.out.println("Attempted to display a null URL.");
}
}
} catch (IOException e) {
System.err.println("Attempted to read a bad URL: " + url);
}
}
private void createNodes(DefaultMutableTreeNode top) {
DefaultMutableTreeNode category = null;
DefaultMutableTreeNode book = null;
category = new DefaultMutableTreeNode("Books for Java Programmers");
top.add(category);
//original Tutorial
book = new DefaultMutableTreeNode(new BookInfo
("The Java Tutorial: A Short Course on the Basics",
"tutorial.html"));
category.add(book);
//Tutorial Continued
book = new DefaultMutableTreeNode(new BookInfo
("The Java Tutorial Continued: The Rest of the JDK",
"tutorialcont.html"));
category.add(book);
//JFC Swing Tutorial
book = new DefaultMutableTreeNode(new BookInfo
("The JFC Swing Tutorial: A Guide to Constructing GUIs",
"swingtutorial.html"));
category.add(book);
//Bloch
book = new DefaultMutableTreeNode(new BookInfo
("Effective Java Programming Language Guide",
"bloch.html"));
category.add(book);
//Arnold/Gosling
book = new DefaultMutableTreeNode(new BookInfo
("The Java Programming Language", "arnold.html"));
category.add(book);
//Chan
book = new DefaultMutableTreeNode(new BookInfo
("The Java Developers Almanac",
"chan.html"));
category.add(book);
category = new DefaultMutableTreeNode("Books for Java Implementers");
top.add(category);
//VM
book = new DefaultMutableTreeNode(new BookInfo
("The Java Virtual Machine Specification",
"vm.html"));
category.add(book);
//Language Spec
book = new DefaultMutableTreeNode(new BookInfo
("The Java Language Specification",
"jls.html"));
category.add(book);
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event dispatch thread.
*/
private static void createAndShowGUI() {
if (useSystemLookAndFeel) {
try {
UIManager.setLookAndFeel(
UIManager.getSystemLookAndFeelClassName());
} catch (Exception e) {
System.err.println("Couldn't use system look and feel.");
}
}
//Create and set up the window.
JFrame frame = new JFrame("TreeDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Add content to the window.
frame.add(new TreeDemo());
//Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event dispatch thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}