import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JOptionPane;
class ShowAction extends AbstractAction {
public ShowAction() {
super("About");
putValue(Action.MNEMONIC_KEY, new Integer(KeyEvent.VK_A));
}
public void actionPerformed(ActionEvent actionEvent) {
System.out.println("w3cschool.cn");
}
}
public class Main {
public static void main(final String args[]) {
JButton bn = new JButton(new ShowAction());
JOptionPane.showMessageDialog(null, bn);
}
}