ComboBox with ActionListener : ActionListener « Swing Event « Java Tutorial






ComboBox with ActionListener
/*
 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

/* ComboBoxDemo2.java requires no other files. */
public class ComboBoxDemo2 extends JPanel implements ActionListener {
  static JFrame frame;
  JLabel result;
  String currentPattern;

  public ComboBoxDemo2() {
    setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
    String[] patternExamples = { "dd MMMMM yyyy", "dd.MM.yy", "MM/dd/yy",
        "yyyy.MM.dd G 'at' hh:mm:ss z", "EEE, MMM d, ''yy", "h:mm a",
        "H:mm:ss:SSS", "K:mm a,z", "yyyy.MMMMM.dd GGG hh:mm aaa" };

    currentPattern = patternExamples[0];

    // Set up the UI for selecting a pattern.
    JLabel patternLabel1 = new JLabel("Enter the pattern string or");
    JLabel patternLabel2 = new JLabel("select one from the list:");

    JComboBox patternList = new JComboBox(patternExamples);
    patternList.setEditable(true);
    patternList.addActionListener(this);

    // Create the UI for displaying result.
    JLabel resultLabel = new JLabel("Current Date/Time", JLabel.LEADING); // ==
                                                                          // LEFT
    result = new JLabel(" ");
    result.setForeground(Color.black);
    result.setBorder(BorderFactory.createCompoundBorder(BorderFactory
        .createLineBorder(Color.black), BorderFactory.createEmptyBorder(5, 5,
        5, 5)));

    // Lay out everything.
    JPanel patternPanel = new JPanel();
    patternPanel.setLayout(new BoxLayout(patternPanel, BoxLayout.PAGE_AXIS));
    patternPanel.add(patternLabel1);
    patternPanel.add(patternLabel2);
    patternList.setAlignmentX(Component.LEFT_ALIGNMENT);
    patternPanel.add(patternList);

    JPanel resultPanel = new JPanel(new GridLayout(0, 1));
    resultPanel.add(resultLabel);
    resultPanel.add(result);

    patternPanel.setAlignmentX(Component.LEFT_ALIGNMENT);
    resultPanel.setAlignmentX(Component.LEFT_ALIGNMENT);

    add(patternPanel);
    add(Box.createRigidArea(new Dimension(0, 10)));
    add(resultPanel);

    setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));

    reformat();
  } // constructor

  public void actionPerformed(ActionEvent e) {
    JComboBox cb = (JComboBox) e.getSource();
    String newSelection = (String) cb.getSelectedItem();
    currentPattern = newSelection;
    reformat();
  }

  /** Formats and displays today's date. */
  public void reformat() {
    Date today = new Date();
    SimpleDateFormat formatter = new SimpleDateFormat(currentPattern);
    try {
      String dateString = formatter.format(today);
      result.setForeground(Color.black);
      result.setText(dateString);
    } catch (IllegalArgumentException iae) {
      result.setForeground(Color.red);
      result.setText("Error: " + iae.getMessage());
    }
  }

  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event-dispatching thread.
   */
  private static void createAndShowGUI() {
    // Create and set up the window.
    JFrame frame = new JFrame("ComboBoxDemo2");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    // Create and set up the content pane.
    JComponent newContentPane = new ComboBoxDemo2();
    newContentPane.setOpaque(true); // content panes must be opaque
    frame.setContentPane(newContentPane);

    // Display the window.
    frame.pack();
    frame.setVisible(true);
  }

  public static void main(String[] args) {
    // Schedule a job for the event-dispatching thread:
    // creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });
  }
}








15.5.ActionListener
15.5.1.implements ActionListener and action class level variable
15.5.2.Handling an action listener
15.5.3.Check the event source in actionPerformed method
15.5.4.Use an Inner Class to handle the event
15.5.5.Use one inner class to handle events from two buttons
15.5.6.Get event source from ActionEvent
15.5.7.Add action listener to JTextField
15.5.8.ComboBox with ActionListenerComboBox with ActionListener
15.5.9.ActionEvent.getActionCommand()
15.5.10.Using an inner ActionListener class.