FileDocCategorySizeDatePackage
TreeLink.javaAPI DocExample3664Wed Jan 20 13:53:06 GMT 1999None

TreeLink

public class TreeLink extends Applet
Applet GUI demo of Gamelan TreeLayout layout manager. Constructs a tree and, for each entry, makes a button that jumps to it. The input language is a file like this: R Java Resources # root L - Resources at Sun # label B http://www.sun.com/foo/bar Interesting Stuff # URLbutton B http://javasoft.com/b/c More Stuff # URLbutton The result is (supposedly) a beautiful(?) tree. Each L is a top-level label, and each B is in the tree below it. Could be made much fancier with getParameter("FontName"), "FontSize", adjusting width with fontMetrics, etc. Works adequately for now.

Fields Summary
Label
root
TreeLayout
tl
Label
l
URLButton
b
Hashtable
h
int
wid
int
ht
int
htIncr
Constructors Summary
Methods Summary
protected voideprintln(java.lang.String s)

		System.err.println(s);
		showStatus("Error, see Java Console");
public java.lang.StringgetAppletInfo()
Return information about this applet.

		return "TreeLink Demo Applet\n" +
			"Copyright Learning Tree International";
public java.lang.String[][]getParameterInfo()
Return list of allowable parameters.

		String param_info[][] = {
			{"TreeLink",    "filename",    "List of links"},
		};
		return param_info;
public voidinit()


	// Initialize this TreeLink applet
	   

		showStatus("TreeLink initializing tree...");

		URL origin = getCodeBase();

		h = new Hashtable();

		// Read the configuration file from the URL.
		try {

			setLayout(tl = new TreeLayout());

			String txt;
			String fn;	// Control file name
			if ((fn = getParameter("treelink")) == null)
				fn = "treelink.txt";
			URL ctlFile = new URL(origin, fn);
			BufferedReader is =
				new BufferedReader(
					new InputStreamReader(ctlFile.openStream()));

			// Read the control file a line at a time, parse
			// it, and save the ones that are links in 
			// the Hashtable indexed by their pushbutton

			while ((txt = is.readLine()) != null) {
				if (txt.startsWith("#"))
					continue;
				StringTokenizer st = new StringTokenizer(txt);
				if (st.countTokens() < 3) {
					println("TreeLink: Bad input: " + txt);
					return;
				}
				String type = st.nextToken();
				String bURL = st.nextToken();
				String text = "";
				while (st.hasMoreTokens())
					text += st.nextToken() + " ";
				// println("Type " + type + "; link " +
				// 	bURL + "; text " + text);
				ht += htIncr;
				if (type.equals("R")) {
					add("root",
					root = new Label(text));
					root.setBackground(Color.pink);
					tl.setRoot(root);	// required!
				} else if (type.equals("L")) {
					add("label", l = new Label(text));
					l.setBackground(Color.pink);
					tl.setParent(l, root);
				} else if (type.equals("B")) {
					URL u;
					if (bURL.indexOf(':") > 0)
						u = new URL(bURL);
					else
						u = new URL(origin, bURL);
					add("button", b = new URLButton(this, text, u));
					tl.setParent(b, l);
				} else {
					println("TreeLink: Invalid input " + txt);
				}
			}
		} catch(MalformedURLException mfc) {
			println("TreeLink: Error: " + mfc);
		} catch(IOException billg) {
			println("TreeLink: Error: " + billg);
		}

		setSize(wid, ht);
		System.out.println("Size now " + getSize());

		showStatus("TreeLink ready");
public voidpaint(java.awt.Graphics g)

		tl.paintLines(g, getForeground());
protected voidprintln(java.lang.String s)

		System.out.println(s);
		showStatus("Informational message(s), see Java Console");