Tóm Tắt
SWING – ActionListener Interface
The class which processes the ActionEvent should implement this interface. The object of that class must be registered with a component. The object can be registered using the addActionListener() method. When the action event occurs, that object’s actionPerformed method is invoked.
Interface Declaration
Following is the declaration for java.awt.event.ActionListener interface −
public interface ActionListener extends EventListener
Interface Methods
Sr.No.
Method & Description
1
void actionPerformed(ActionEvent e)
Invoked when an action occurs.
Methods Inherited
This interface inherits methods from the following interfaces −
java.awt.EventListener
ActionListener Example
Create the following Java program using any editor of your choice in say D:/ > SWING > com > tutorialspoint > gui >
SwingListenerDemo.java
package com.tutorialspoint.gui; import java.awt.*; import java.awt.event.*; import javax.swing.*; public class SwingListenerDemo { private JFrame mainFrame; private JLabel headerLabel; private JLabel statusLabel; private JPanel controlPanel; public SwingListenerDemo(){ prepareGUI(); } public static void main(String[] args){ SwingListenerDemo swingListenerDemo = new SwingListenerDemo(); swingListenerDemo.showActionListenerDemo(); } private void prepareGUI(){ mainFrame = new JFrame("Java SWING Examples"); mainFrame.setSize(400,400); mainFrame.setLayout(new GridLayout(3, 1)); headerLabel = new JLabel("",JLabel.CENTER ); statusLabel = new JLabel("",JLabel.CENTER); statusLabel.setSize(350,100); mainFrame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent windowEvent){ System.exit(0); } }); controlPanel = new JPanel(); controlPanel.setLayout(new FlowLayout()); mainFrame.add(headerLabel); mainFrame.add(controlPanel); mainFrame.add(statusLabel); mainFrame.setVisible(true); } private void showActionListenerDemo(){ headerLabel.setText("Listener in action: ActionListener"); JPanel panel = new JPanel(); panel.setBackground(Color.magenta); JButton okButton = new JButton("OK"); okButton.addActionListener(new CustomActionListener()); panel.add(okButton); controlPanel.add(panel); mainFrame.setVisible(true); } class CustomActionListener implements ActionListener{ public void actionPerformed(ActionEvent e) { statusLabel.setText("Ok Button Clicked."); } } }
Compile the program using the command prompt. Go to D:/ > SWING and type the following command.
D:\SWING>javac com\tutorialspoint\gui\SwingListenerDemo.java
If no error occurs, it means the compilation is successful. Run the program using the following command.
D:\SWING>java com.tutorialspoint.gui.SwingListenerDemo
Verify the following output.
swing_event_listeners.htm
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