Demonstrates the use of a JColorChooser which presents a dialog with three different tabbed panes to allow the user to select a color preference. The dialog returns a Color object based on the user's selection or null if the user entered Cancel.

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

/** Simple example illustrating the use of JColorChooser. 
 *
 *  .
 */

public class JColorChooserTest extends JFrame
                               implements ActionListener {
  public static void main(String[] args) {
    new JColorChooserTest();
  }

  public JColorChooserTest() {
    super("Using JColorChooser");
    WindowUtilities.setNativeLookAndFeel();
    addWindowListener(new ExitListener());
    Container content = getContentPane();
    content.setBackground(Color.white);
    content.setLayout(new FlowLayout());
    JButton colorButton
      = new JButton("Choose Background Color");
    colorButton.addActionListener(this);
    content.add(colorButton);
    setSize(300, 100);
    setVisible(true);
  }

  public void actionPerformed(ActionEvent e) {
    // Args are parent component, title, initial color.
    Color bgColor
      = JColorChooser.showDialog(this,
                                 "Choose Background Color",
                                 getBackground());
    if (bgColor != null)
      getContentPane().setBackground(bgColor);
  }
}

/** A template to control the state of a thread through setting
 *  an internal flag.

public class StoppableThread extends Thread {

   public static final int STOP    = 0;
   public static final int RUN     = 1;
   public static final int WAIT    = 2;
   private int state = RUN;

  /** Public method to permit setting a flag to stop or
   *  suspend the thread.  The state is monitored through the
   *  corresponding checkState method.
   */

   public synchronized void setState(int state) {
      this.state = state;
      if (state==RUN) {
         notify();
      }
   }

  /** Returns the desired state of the thread (RUN, STOP, WAIT).
   *  Normally, you may want to change the state or perform some
   *  other task if an InterruptedException occurs.
   */

   private synchronized int checkState() {
      while (state==WAIT) {
        try {
          wait();
        } catch (InterruptedException e) { }
      }
      return state;
   }

  /** An example of thread that will continue to run until
   *  the creating object tells the thread to STOP.
   */

   public void run() {
      while (checkState()!=STOP) {
         ...
      }
   }
}

mall example showing the basic use of a JToolBar

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

/** Small example showing basic use of JToolBar. 
 *
 * 
 */

public class JToolBarExample extends JFrame
                             implements ItemListener {
  private BrowserToolBar toolbar;
  private JCheckBox labelBox;

  public static void main(String[] args) {
    new JToolBarExample();
  }

  public JToolBarExample() {
    super("JToolBar Example");
    WindowUtilities.setNativeLookAndFeel();
    addWindowListener(new ExitListener());
    Container content = getContentPane();
    content.setBackground(Color.white);
    
    JPanel panel = new JPanel(new BorderLayout());
    labelBox = new JCheckBox("Show Text Labels?");
    labelBox.setHorizontalAlignment(SwingConstants.CENTER);
    labelBox.addItemListener(this);
    panel.add(new JTextArea(10,30), BorderLayout.CENTER);
    panel.add(labelBox, BorderLayout.SOUTH);

    toolbar = new BrowserToolBar();
    content.add(toolbar, BorderLayout.NORTH);
    content.add(panel, BorderLayout.CENTER);

    pack();
    setVisible(true);
  }

  public void itemStateChanged(ItemEvent event) {
    toolbar.setTextLabels(labelBox.isSelected());
    pack();
  }
}

UrlRetriever2.java  Illustrates how the URL class can simplify communication to an HTTP server.

import java.net.*;
import java.io.*;

/** Read a remote file using the standard URL class
 *  instead of connecting explicitly to the HTTP server.
 *
 *  Taken from Core Web Programming from
 *  Prentice Hall and Sun Microsystems Press,
 *  .
 *  © 2001 Marty Hall and Larry Brown;
 *  may be freely used or adapted.
 */

public class UrlRetriever2 {
  public static void main(String[] args) {
    checkUsage(args);
    try {
      URL url = new URL(args[0]);
      BufferedReader in = new BufferedReader(
        new InputStreamReader(url.openStream()));
      String line;
      while ((line = in.readLine()) != null) {
        System.out.println("> " + line);
     }
      in.close();
    } catch(MalformedURLException mue) { // URL constructor
        System.out.println(args[0] + "is an invalid URL: " + mue);
    } catch(IOException ioe) { // Stream constructors
      System.out.println("IOException: " + ioe);
    }
  }

  private static void checkUsage(String[] args) {
    if (args.length != 1) {
      System.out.println("Usage: UrlRetriever2 ");
      System.exit(-1);
    }
  }
}

• WindowUtilities.java Utility class that simplifies creating a window and setting the look and feel.
• ExitListener.java A WindowListener with support to close the window.
• JAppletExample.java A simple applet (JApplet) created in Swing. Illustrates setting the look and feel, adding components to the content pane, and changing the layout to FlowLayout (default is BorderLayout). See JAppletExample.html (requires the Java Plug-In or a Java 2 compliant browser, for example, Netscape 6.x).
• JFrameExample.java Demonstrates creating a simple Swing application using a JFrame. As with a JApplet, components must be added to the content pane, instead of the window directly.
• JLabels.java Illustrates creating labels in Swing. A nice feature of JLabels is that the label text can contain HTML markup. Uses image JHUAPL.gif
• JButtons.java Creates various buttons. In Swing, buttons can contain text only, an image only, or a combination of both an image and a label. Uses image cup.gif.
• JPanels.java A simple example that illustrates creating panels. In Swing, a JPanel can contain custom borders. Typically, utility methods in the BorderFactory class are used to create a border for the panel. Uses the following class:
  o SixChoicePanel.java A JPanel that displays six radio buttons with labels.
• JSliders.java Creates three common types of sliders: one without tick marks, one with tick marks, and one with both tick marks and labels.
• JColorChooserTest.java Demonstrates the use of a JColorChooser which presents a dialog with three different tabbed panes to allow the user to select a color preference. The dialog returns a Color object based on the user's selection or null if the user entered Cancel.
• JInternalFrames.java Illustrates the ability to create a Multiple Document Interface (MDI) application by placing internal frames (JInternalFrame) in a desktop pane (JDesktopPane).
• JToolBarExample.java Small example showing the basic use of a JToolBar. Uses the following classes and images:
  o ToolBarButton.java A simple button that contains an image and a label for use in a toolbar.
  o BrowserToolBar.java A basic tool bar for holding multiple buttons.
  o Images used in the toolbar buttons: Help.gif, Home.gif, Left.gif, Print.gif, Right.gif, RotCCUp.gif, TrafficRed.gif.
• Browser.java Implementation of a simple browser in Swing. The user can specify a URL to load into the browser (JEditorPane). By attaching an HyperlinkListener, the editor pane is responsive to hyperlinks selected by the user. Uses the following class and image:
  o JIconButton.java A simple button that the user can select to load the entered URL.
  o home.gif Image used in the button.
• JCheckBoxTest.java Simple example illustrating the use of check boxes.
• JRadioButtonTest.java Creates three radio buttons and illustrates handling ItemEvents in response to selecting a radio button.
• JOptionPaneExamples.java Creates various modal dialogs to show messages. Uses the follwoing classes:
  o JLabeledTextField.java A simple JPanel that combines a JLabel and a JTextField.
  o RadioButtonPanel.java Groups several radio buttons in a single row, with a label on the left.
  o DisableListener.java A listener that toggles the enabled status of some other component.

import java.applet.Applet;
import java.awt.*;

/** Emulates the Counter and Counter2 classes, but this time
 *  from an applet that invokes multiple versions of its own run
 *  method. This version is likely to work correctly
 *  except when  an important customer is visiting.

public class BuggyCounterApplet extends Applet
                                implements Runnable{
  private int totalNum = 0;
  private int loopLimit = 5;

  // Start method of applet, not the start method of the thread. 
  // The applet start method is called by the browser after init is
  // called. 
  public void start() {
    Thread t;
    for(int i=0; i<3; i++) {
      t = new Thread(this);
      t.start();
    }
  }

  private void pause(double seconds) {
    try { Thread.sleep(Math.round(1000.0*seconds)); }
    catch(InterruptedException ie) {}
  }

  public void run() {
    int currentNum = totalNum;
    System.out.println("Setting currentNum to " + currentNum);
    totalNum = totalNum + 1;
    for(int i=0; i

TokTest.java  Illustrates parsing a string with a StringTokenizer. 

import java.util.StringTokenizer;

/** Prints the tokens resulting from treating the first
 *  command-line argument as the string to be tokenized
 *  and the second as the delimiter set.
 *
 *  Taken from Core Web Programming from
 *  Prentice Hall and Sun Microsystems Press,
 *  .
 *  © 2001 Marty Hall and Larry Brown;
 *  may be freely used or adapted.
 */

public class TokTest {
  public static void main(String[] args) {
    if (args.length == 2) {
      String input = args[0], delimiters = args[1];
      StringTokenizer tok =
        new StringTokenizer(input, delimiters);
      while (tok.hasMoreTokens()) {
        System.out.println(tok.nextToken());
      }
    } else {
      System.out.println
        ("Usage: java TokTest string delimeters");
    }
  }
}

LongLivedCookie.java  Subclass of Cookie that automatically sets the max age to one year. 

package cwp;

import javax.servlet.http.*;

/** Cookie that persists 1 year. Default Cookie doesn't
 *  persist past current session.
 *  


 *  Taken from Core Web Programming Java 2 Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  .
 *  May be freely used or adapted.
 */

public class LongLivedCookie extends Cookie {
  public static final int SECONDS_PER_YEAR = 60*60*24*365;

  public LongLivedCookie(String name, String value) {
    super(name, value);
    setMaxAge(SECONDS_PER_YEAR);
  }
}

ServletTemplate.java Starting point for servlets. 


import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

/** Servlet template.
 *  


 *  Taken from Core Web Programming Java 2 Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  .
 *  May be freely used or adapted.
 */

public class ServletTemplate extends HttpServlet {
  public void doGet(HttpServletRequest request,
                    HttpServletResponse response)
      throws ServletException, IOException {

    // Use "request" to read incoming HTTP headers
    // (e.g., cookies) and query data from HTML forms.

    // Use "response" to specify the HTTP response status
    // code and headers (e.g. the content type, cookies).

    PrintWriter out = response.getWriter();
    // Use "out" to send content to browser
  }
}

# QueryViewer.java  An interactive database query viewer. Connects to the specified Oracle or Sybase database, executes a query, and presents the results in a JTable. Uses the following file:

    * DBResultsTableModel.java Simple class that tells a JTable how to extract relevant data from a DBResults object (which is used to store the results from a database query). 
############################################################################

  package cwp;

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

/** An interactive database query viewer. Connects to
 *  the specified Oracle or Sybase database, executes a query,
 *  and presents the results in a JTable.
 *  


 */

public class QueryViewer extends JFrame
                         implements ActionListener{
  public static void main(String[] args) {
    new QueryViewer();
  }

  private JTextField hostField, dbNameField,
                     queryField, usernameField;
  private JRadioButton oracleButton, sybaseButton;
  private JPasswordField passwordField;
  private JButton showResultsButton;
  Container contentPane;
  private JPanel tablePanel;
  
  public QueryViewer () {
    super("Database Query Viewer");
    WindowUtilities.setNativeLookAndFeel();
    addWindowListener(new ExitListener());
    contentPane = getContentPane();
    contentPane.add(makeControlPanel(), BorderLayout.NORTH);
    pack();
    setVisible(true);
  }

  /** When the "Show Results" button is pressed or
   *  RETURN is hit while the query textfield has the
   *  keyboard focus, a database lookup is performed,
   *  the results are placed in a JTable, and the window
   *  is resized to accommodate the table.
   */
  
  public void actionPerformed(ActionEvent event) {
    String host = hostField.getText();
    String dbName = dbNameField.getText();
    String username = usernameField.getText();
    String password =
      String.valueOf(passwordField.getPassword());
    String query = queryField.getText();
    int vendor;
    if (oracleButton.isSelected()) {
      vendor = DriverUtilities.ORACLE;
    } else {
      vendor = DriverUtilities.SYBASE;
    }
    if (tablePanel != null) {
      contentPane.remove(tablePanel);
    }
    tablePanel = makeTablePanel(host, dbName, vendor,
                                username, password,
                                query);
    contentPane.add(tablePanel, BorderLayout.CENTER);
    pack();
  }

  // Executes a query and places the result in a
  // JTable that is, in turn, inside a JPanel.
  
  private JPanel makeTablePanel(String host,
                                String dbName,
                                int vendor,
                                String username,
                                String password,
                                String query) {
    String driver = DriverUtilities.getDriver(vendor);
    String url = DriverUtilities.makeURL(host, dbName, vendor);
    DBResults results =
      DatabaseUtilities.getQueryResults(driver, url,
                                        username, password,
                                        query, true);
    JPanel panel = new JPanel(new BorderLayout());
    if (results == null) {
      panel.add(makeErrorLabel());
      return(panel);
    }
    DBResultsTableModel model =
      new DBResultsTableModel(results);
    JTable table = new JTable(model);
    table.setFont(new Font("Serif", Font.PLAIN, 17));
    table.setRowHeight(28);
    JTableHeader header = table.getTableHeader();
    header.setFont(new Font("SansSerif", Font.BOLD, 13));
    panel.add(table, BorderLayout.CENTER);
    panel.add(header, BorderLayout.NORTH);
    panel.setBorder
      (BorderFactory.createTitledBorder("Query Results"));
    return(panel);
  }

  // The panel that contains the textfields, checkboxes,
  // and button.
  
  private JPanel makeControlPanel() {
    JPanel panel = new JPanel(new GridLayout(0, 1));
    panel.add(makeHostPanel());
    panel.add(makeUsernamePanel());
    panel.add(makeQueryPanel());
    panel.add(makeButtonPanel());
    panel.setBorder
      (BorderFactory.createTitledBorder("Query Data"));
    return(panel);
  }

  // The panel that has the host and db name textfield and
  // the driver radio buttons. Placed in control panel.
  
  private JPanel makeHostPanel() {
    JPanel panel = new JPanel();
    panel.add(new JLabel("Host:"));
    hostField = new JTextField(15);
    panel.add(hostField);
    panel.add(new JLabel("    DB Name:"));
    dbNameField = new JTextField(15);
    panel.add(dbNameField);
    panel.add(new JLabel("    Driver:"));
    ButtonGroup vendorGroup = new ButtonGroup();
    oracleButton = new JRadioButton("Oracle", true);
    vendorGroup.add(oracleButton);
    panel.add(oracleButton);
    sybaseButton = new JRadioButton("Sybase");
    vendorGroup.add(sybaseButton);
    panel.add(sybaseButton);
    return(panel);
  }

  // The panel that has the username and password textfields.
  // Placed in control panel.
  
  private JPanel makeUsernamePanel() {
    JPanel panel = new JPanel();
    usernameField = new JTextField(10);
    passwordField = new JPasswordField(10);
    panel.add(new JLabel("Username: "));
    panel.add(usernameField);
    panel.add(new JLabel("    Password:"));
    panel.add(passwordField);
    return(panel);
  }

  // The panel that has textfield for entering queries.
  // Placed in control panel.
  
  private JPanel makeQueryPanel() {
    JPanel panel = new JPanel();
    queryField = new JTextField(40);
    queryField.addActionListener(this);
    panel.add(new JLabel("Query:"));
    panel.add(queryField);
    return(panel);
  }

  // The panel that has the "Show Results" button.
  // Placed in control panel.
  
  private JPanel makeButtonPanel() {
    JPanel panel = new JPanel();
    showResultsButton = new JButton("Show Results");
    showResultsButton.addActionListener(this);
    panel.add(showResultsButton);
    return(panel);
  }

  // Shows warning when bad query sent.
  
  private JLabel makeErrorLabel() {
    JLabel label = new JLabel("No Results", JLabel.CENTER);
    label.setFont(new Font("Serif", Font.BOLD, 36));
    return(label);
  }
}

package cwp;

import java.sql.*;

/** Make a simple "employees" table using DatabaseUtilities.
 */

public class EmployeeCreation {
  public static Connection createEmployees(String driver,
                                           String url,
                                           String username,
                                           String password,
                                           boolean close) {
    String format =
      "(id int, firstname varchar(32), lastname varchar(32), " +
      "language varchar(16), salary float)";
    String[] employees =
      {"(1, 'Wye', 'Tukay', 'COBOL', 42500)",
       "(2, 'Britt', 'Tell',   'C++',   62000)",
       "(3, 'Max',  'Manager', 'none',  15500)",
       "(4, 'Polly', 'Morphic', 'Smalltalk', 51500)",
       "(5, 'Frank', 'Function', 'Common Lisp', 51500)",
       "(6, 'Justin', 'Timecompiler', 'Java', 98000)",
       "(7, 'Sir', 'Vlet', 'Java', 114750)",
       "(8, 'Jay', 'Espy', 'Java', 128500)" };
    return(DatabaseUtilities.createTable(driver, url,
                                         username, password,
                                         "employees",
                                         format, employees,
                                         close));    
  }

  public static void main(String[] args) {
    if (args.length < 5) {
      printUsage();
      return;
    }
    String vendorName = args[4];
    int vendor = DriverUtilities.getVendor(vendorName);
    if (vendor == DriverUtilities.UNKNOWN) {
      printUsage();
      return;
    }
    String driver = DriverUtilities.getDriver(vendor);
    String host = args[0];
    String dbName = args[1];
    String url =
      DriverUtilities.makeURL(host, dbName, vendor);
    String username = args[2];
    String password = args[3];
    createEmployees(driver, url, username, password, true);
  }

  private static void printUsage() {
    System.out.println("Usage: EmployeeCreation host dbName " +
                       "username password oracle|sybase.");
  }
}

ClickReporter.java A simple applet that uses the ClickListener class to handle mouse events.
***************
import java.applet.Applet;
import java.awt.*;

/** Prints a message saying where the user clicks.
 *  Uses an external listener.
 *  


 ******
public class ClickReporter extends Applet {
  public void init() {
    setBackground(Color.yellow);
    addMouseListener(new ClickListener());
  }
}