WindowUtilities & DrawingPanel

What is still wrong with this piece of code? WindowUtilities &  DrawingPanel  are detected as  unfound symbols

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.print.*;


public class PrintExample extends JFrame
implements ActionListener

{
  public static void main(String[] args)
  {
    new PrintExample();
  }

  public PrintExample() {
    super("Printing Swing Components");
    WindowUtilities.setNativeLookAndFeel(); <<=====
    addWindowListener(new ExitListener()); <<=====
    Container content = getContentPane();
    JButton printButton = new JButton("Print");
    printButton.addActionListener(this);
    JPanel buttonPanel = new JPanel();
    buttonPanel.setBackground(Color.white);
    buttonPanel.add(printButton);
    content.add(buttonPanel, BorderLayout.SOUTH);
    DrawingPanel drawingPanel = new DrawingPanel();<<=====
    content.add(drawingPanel, BorderLayout.CENTER);
    pack();
    setVisible(true);
  }

  public void actionPerformed(ActionEvent event) {
    PrintUtilities.printComponent(this);
  }
 
}