Java Tutorial/Swing Event/ActionListener
Содержание
- 1 ActionEvent.getActionCommand()
- 2 Add action listener to JTextField
- 3 Check the event source in actionPerformed method
- 4 ComboBox with ActionListener
- 5 Get event source from ActionEvent
- 6 Handling an action listener
- 7 implements ActionListener and action class level variable
- 8 Use an Inner Class to handle the event
- 9 Use one inner class to handle events from two buttons
- 10 Using an inner ActionListener class.
ActionEvent.getActionCommand()
<source lang="java">
import java.awt.FlowLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; class ButtonDemo implements ActionListener {
JButton jbtnA = new JButton("Alpha"); JButton jbtnB = new JButton("Beta"); ButtonDemo() { JFrame jfrm = new JFrame("A Button Example"); jfrm.setLayout(new FlowLayout()); jfrm.setSize(220, 90); jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); jbtnA.addActionListener(this); jbtnB.addActionListener(this); jfrm.add(jbtnA); jfrm.add(jbtnB); jfrm.setVisible(true); } public void actionPerformed(ActionEvent ae) { String ac = ae.getActionCommand(); if (ac.equals("Alpha")) { if (jbtnB.isEnabled()) { System.out.println("Alpha pressed. Beta is disabled."); jbtnB.setEnabled(false); } else { System.out.println("Alpha pressed. Beta is enabled."); jbtnB.setEnabled(true); } } else if (ac.equals("Beta")) System.out.println("Beta pressed."); } public static void main(String args[]) { new ButtonDemo(); }
}</source>
Add action listener to JTextField
<source lang="java">
import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.JFrame; import javax.swing.JTextField; public class Test extends JFrame {
JTextField text = new JTextField("Press Return", 40); public Test() { setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); text.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { System.out.println("Text=" + text.getText()); } }); getContentPane().add(text, "Center"); pack(); } public static void main(String[] args) { new Test().setVisible(true); }
}</source>
Check the event source in actionPerformed method
<source lang="java">
import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; public class MainClass extends JFrame implements ActionListener {
private JButton button1 = new JButton("Click Me!"); private int clickCount = 0; public static void main(String[] args) { new MainClass(); } public MainClass() { this.setSize(200, 100); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setTitle("I"m Listening"); JPanel panel1 = new JPanel(); button1.addActionListener(this); panel1.add(button1); this.add(panel1); this.setVisible(true); } public void actionPerformed(ActionEvent e) { if (e.getSource() == button1) { clickCount++; if (clickCount == 1) button1.setText("I"ve been clicked!"); else button1.setText("I"ve been clicked" + clickCount + " times!"); } }
}</source>
ComboBox with ActionListener
<source lang="java">
/*
* 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.ruponent; 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(); } }); }
}</source>
Get event source from ActionEvent
<source lang="java">
import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JPanel; public class MainClass extends JFrame {
public static void main(String[] args) { new MainClass(); } private JButton button1 = new JButton("Click Me!"), exitButton= new JButton("Exit"); public MainClass() { this.setSize(275, 100); this.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE); ClickListener cl = new ClickListener(); JPanel panel1 = new JPanel(); addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { exitButton.doClick(); } }); button1.addActionListener(cl); panel1.add(button1); exitButton.addActionListener(cl); panel1.add(exitButton); this.add(panel1); this.setVisible(true); } private class ClickListener implements ActionListener { private int clickCount = 0; public void actionPerformed(ActionEvent e) { if (e.getSource() == button1) { clickCount++; if (clickCount == 1) button1.setText("clicked!"); else button1.setText("clicked " + clickCount + " times!"); } else if (e.getSource() == exitButton) { if (clickCount > 0) System.exit(0); else { JOptionPane.showMessageDialog(MainClass.this, "You must click at least once!", "Title", JOptionPane.ERROR_MESSAGE); } } } }
}</source>
Handling an action listener
<source lang="java">
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.JOptionPane; class MyActionListener implements ActionListener {
public void actionPerformed(ActionEvent e) { JButton source = (JButton) e.getSource(); String buttonText = source.getText(); JOptionPane.showMessageDialog(null, "You clicked" + buttonText); }
} public class ActionListenerTest1 {
public static void main(String[] args) { JFrame.setDefaultLookAndFeelDecorated(true); JDialog.setDefaultLookAndFeelDecorated(true); JFrame frame = new JFrame("ActionListener Test 1"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JButton button = new JButton("Register"); button.addActionListener(new MyActionListener()); frame.getContentPane().add(button); frame.pack(); frame.setVisible(true); }
}</source>
implements ActionListener and action class level variable
<source lang="java">
import java.awt.BorderLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JTextField; public class MainClass extends JFrame {
JTextField field = new JTextField(); public static void main(String[] args) { MainClass st = new MainClass(); } public SwingTest() { setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JButton button = new JButton("Press me"); button.addActionListener(new ButtonListener()); this.getContentPane().setLayout(new BorderLayout()); this.getContentPane().add(button, BorderLayout.SOUTH); this.getContentPane().add(field, BorderLayout.NORTH); this.pack(); this.setVisible(true); } class ButtonListener implements ActionListener { boolean toggle = true; public void actionPerformed(ActionEvent e) { if (toggle) field.setText("Simple"); else field.setText("Sample"); toggle = !toggle; } }
}</source>
Use an Inner Class to handle the event
<source lang="java">
import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; public class MainClass extends JFrame {
private JButton button1 = new JButton("Click Me!"); public static void main(String[] args) { new MainClass(); } public MainClass() { this.setSize(200, 100); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setTitle("I"m Listening"); ClickListener cl = new ClickListener(); JPanel panel1 = new JPanel(); button1.addActionListener(cl); panel1.add(button1); this.add(panel1); this.setVisible(true); } private class ClickListener implements ActionListener { private int clickCount = 0; public void actionPerformed(ActionEvent e) { if (e.getSource() == button1) { clickCount++; if (clickCount == 1) button1.setText("I"ve been clicked "); else button1.setText("I"ve been clicked!" + clickCount + " times!"); } } }
}</source>
Use one inner class to handle events from two buttons
<source lang="java">
import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JPanel; public class MainClass extends JFrame {
public static void main(String[] args) { new MainClass(); } private JButton button1 = new JButton("Click Me!"), exitButton= new JButton("Exit"); public MainClass() { this.setSize(275, 100); this.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE); ClickListener cl = new ClickListener(); JPanel panel1 = new JPanel(); addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { exitButton.doClick(); } }); button1.addActionListener(cl); panel1.add(button1); exitButton.addActionListener(cl); panel1.add(exitButton); this.add(panel1); this.setVisible(true); } private class ClickListener implements ActionListener { private int clickCount = 0; public void actionPerformed(ActionEvent e) { if (e.getSource() == button1) { clickCount++; if (clickCount == 1) button1.setText("clicked!"); else button1.setText("clicked " + clickCount + " times!"); } else if (e.getSource() == exitButton) { if (clickCount > 0) System.exit(0); else { JOptionPane.showMessageDialog(MainClass.this, "You must click at least once!", "Title", JOptionPane.ERROR_MESSAGE); } } } }
}</source>
Using an inner ActionListener class.
<source lang="java">
import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; public class InnerClass {
class ButtonListener implements ActionListener { public void actionPerformed(ActionEvent e) { System.exit(0); } } public InnerClass() { JButton close = new JButton("Close"); ButtonListener listener = new ButtonListener(); close.addActionListener(listener); JFrame f = new JFrame(); f.add(close); f.setSize(300, 200); f.setLocationRelativeTo(null); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setVisible(true); } public static void main(String[] args) { new InnerClass(); }
}</source>