Java tutorial
/* This program is a part of the companion code for Core Java 8th ed. (http://horstmann.com/corejava) This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ import java.awt.BorderLayout; import java.awt.Component; import java.awt.EventQueue; import java.awt.Frame; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JDialog; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JPanel; import javax.swing.JPasswordField; import javax.swing.JScrollPane; import javax.swing.JTextArea; import javax.swing.JTextField; import javax.swing.SwingUtilities; /** * @version 1.33 2007-06-12 * @author Cay Horstmann */ public class DataExchangeTest { public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { DataExchangeFrame frame = new DataExchangeFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } }); } } /** * A frame with a menu whose File->Connect action shows a password dialog. */ class DataExchangeFrame extends JFrame { public DataExchangeFrame() { setTitle("DataExchangeTest"); setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT); // construct a File menu JMenuBar mbar = new JMenuBar(); setJMenuBar(mbar); JMenu fileMenu = new JMenu("File"); mbar.add(fileMenu); // add Connect and Exit menu items JMenuItem connectItem = new JMenuItem("Connect"); connectItem.addActionListener(new ConnectAction()); fileMenu.add(connectItem); // The Exit item exits the program JMenuItem exitItem = new JMenuItem("Exit"); exitItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { System.exit(0); } }); fileMenu.add(exitItem); textArea = new JTextArea(); add(new JScrollPane(textArea), BorderLayout.CENTER); } public static final int DEFAULT_WIDTH = 300; public static final int DEFAULT_HEIGHT = 200; private PasswordChooser dialog = null; private JTextArea textArea; /** * The Connect action pops up the password dialog. */ private class ConnectAction implements ActionListener { public void actionPerformed(ActionEvent event) { // if first time, construct dialog if (dialog == null) dialog = new PasswordChooser(); // set default values dialog.setUser(new User("yourname", null)); // pop up dialog if (dialog.showDialog(DataExchangeFrame.this, "Connect")) { // if accepted, retrieve user input User u = dialog.getUser(); textArea.append( "user name = " + u.getName() + ", password = " + (new String(u.getPassword())) + "\n"); } } } } /** * A password chooser that is shown inside a dialog */ class PasswordChooser extends JPanel { public PasswordChooser() { setLayout(new BorderLayout()); // construct a panel with user name and password fields JPanel panel = new JPanel(); panel.setLayout(new GridLayout(2, 2)); panel.add(new JLabel("User name:")); panel.add(username = new JTextField("")); panel.add(new JLabel("Password:")); panel.add(password = new JPasswordField("")); add(panel, BorderLayout.CENTER); // create Ok and Cancel buttons that terminate the dialog okButton = new JButton("Ok"); okButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { ok = true; dialog.setVisible(false); } }); JButton cancelButton = new JButton("Cancel"); cancelButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { dialog.setVisible(false); } }); // add buttons to southern border JPanel buttonPanel = new JPanel(); buttonPanel.add(okButton); buttonPanel.add(cancelButton); add(buttonPanel, BorderLayout.SOUTH); } /** * Sets the dialog defaults. * @param u the default user information */ public void setUser(User u) { username.setText(u.getName()); } /** * Gets the dialog entries. * @return a User object whose state represents the dialog entries */ public User getUser() { return new User(username.getText(), password.getPassword()); } /** * Show the chooser panel in a dialog * @param parent a component in the owner frame or null * @param title the dialog window title */ public boolean showDialog(Component parent, String title) { ok = false; // locate the owner frame Frame owner = null; if (parent instanceof Frame) owner = (Frame) parent; else owner = (Frame) SwingUtilities.getAncestorOfClass(Frame.class, parent); // if first time, or if owner has changed, make new dialog if (dialog == null || dialog.getOwner() != owner) { dialog = new JDialog(owner, true); dialog.add(this); dialog.getRootPane().setDefaultButton(okButton); dialog.pack(); } // set title and show dialog dialog.setTitle(title); dialog.setVisible(true); return ok; } private JTextField username; private JPasswordField password; private JButton okButton; private boolean ok; private JDialog dialog; } /** * A user has a name and password. For security reasons, the password is stored as a char[], not a * String. */ class User { public User(String aName, char[] aPassword) { name = aName; password = aPassword; } public String getName() { return name; } public char[] getPassword() { return password; } public void setName(String aName) { name = aName; } public void setPassword(char[] aPassword) { password = aPassword; } private String name; private char[] password; }