Java JFrame set window type

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class Main extends JFrame {

   public Main() {
      this.setTitle("Example");
      this.setBounds(100, 100, 200, 200);
      this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      this.setType(Type.UTILITY);
      this.setLayout(new FlowLayout());

      JButton exitButton = new JButton("Exit");
      this.add(exitButton);
      exitButton.addActionListener(new ActionListener() {

         public void actionPerformed(ActionEvent event) {
            System.exit(0);// w  w w  .j  a va 2  s. co  m
         }
      });
   }

   public static void main(String[] args) {
//        JFrame.setDefaultLookAndFeelDecorated(true);
      SwingUtilities.invokeLater(new Runnable() {
         @Override
         public void run() {
            Main window = new Main();
            window.setVisible(true);
         }
      });

   }
}