A JButton example showing ActionListener, ActionEvent, setMnemonic, and actionPerformed

The following source code comes from Sun Microsystems, and shows various things related to showing and clicking a JButton, including using the JButton class, ActionListener, ActionEvent, setMnemonic, and actionPerformed.

jbutton, actionperformed, actionlistener, actionevent, setmnemonic, java, swing, jframe, jpanel

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 * This software is provided "AS IS," without a warranty of any kind. ALL
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// v 1.3

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;

public class SwingApplication {
  private static String labelPrefix = "Number of button clicks: ";

  private int numClicks = 0;

  public Component createComponents() {
    final JLabel label = new JLabel(labelPrefix + "0    ");

    JButton button = new JButton("I'm a Swing button!");
    button.setMnemonic(KeyEvent.VK_I);
    button.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        numClicks++;
        label.setText(labelPrefix + numClicks);
      }
    });
    label.setLabelFor(button);

    /**
     * An easy way to put space between a top-level container and its
     * contents is to put the contents in a JPanel that has an "empty"
     * border.
     */
    JPanel pane = new JPanel();
    pane.setBorder(BorderFactory.createEmptyBorder(30, //top
        30, //left
        10, //bottom
        30) //right
        );
    pane.setLayout(new GridLayout(0, 1));
    pane.add(button);
    pane.add(label);

    return pane;
  }

  public static void main(String[] args) {
    try {
      UIManager.setLookAndFeel(UIManager
          .getCrossPlatformLookAndFeelClassName());
    } catch (Exception e) {
    }

    //Create the top-level container and add contents to it.
    JFrame frame = new JFrame("SwingApplication");
    SwingApplication app = new SwingApplication();
    Component contents = app.createComponents();
    frame.getContentPane().add(contents, BorderLayout.CENTER);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
  }
}