How do I activate JButton ActionListener inside code (unit testing purposes)?

public class MyDialog extends JDialog {
    public static int APPLY_OPTION= 1;
    protected int buttonpressed;
    protected JButton okButton;
    public MyDialog(Frame f) {
    	super(f);
    	okButton.addActionListener(new ActionListener() {
    		public void actionPerformed(ActionEvent e) {
    			buttonpressed= APPLY_OPTION;
    		}
    	} );
    public int getButtonPressed() {
    	return buttonpressed;
    }

}

public class testMyDialog {

    @Test
    public void testGetButtonPressed() {
    	MyDialog fc= new MyDialog(null);
    	fc.okButton.???????? //how do I activate the ActionListener?
    	assertEquals(MyDialog.APPLY_OPTION, fc.getButtonPressed());
    }
}

JButton button = (JButton)PrivateAccessor.get(MyDialog , "okButton");
Thread t = new Thread(new Runnable() {
    public void run() {
        // What ever you want
    };
});

t.start();

button.doClick();

t.join();