import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main extends JFrame {
final JButton b = new JButton("Add");
int size = 10;
public Main() {
setSize(300, 150);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setLayout(new FlowLayout());
add(b);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ev) {
b.setFont(new Font("Dialog", Font.PLAIN, ++size));
b.revalidate();
}
});
setVisible(true);
}
public static void main(String[] args) {
new Main();
}
}