Add Image to Button GUI Java

import java.awt.*; 
 import javax.swing.*; 
 import java.awt.event.*; 
 /*<APPLET CODE=JavaExampleImageButtonInApplet.class WIDTH=510 HEIGHT=210> </APPLET>*/ 
 public class JavaExampleImageButtonInApplet extends JApplet 
     { 
         JButton Btn = new JButton("Button", new ImageIcon("Koala.jpg")); 
         JTextField Txt = new JTextField(22); 
         public void init() 
          { 
             Container Cntnr = getContentPane(); 
             Cntnr.setLayout(new FlowLayout()); 
             Cntnr.add(Btn); 
             Cntnr.add(Txt); 
             Btn.addActionListener(new ActionListener() 
             { 
                 public void actionPerformed(ActionEvent event) 
                 { 
                        Txt.setText("Hi Welcome To Java!"); 
                     } 
             }); 
         } 
     }