// Fig. 6.13: FibonacciTest.java
// Recursive fibonacci method
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class FibonacciTest extends JApplet
             implements ActionListener {
   JLabel numLabel, resultLabel;
   JTextField num, result;

   public void init()
   {
      Container c = getContentPane();
      c.setLayout( new FlowLayout() );

      numLabel = 
         new JLabel( "Enter an integer and press Enter" );
      c.add( numLabel );

      num = new JTextField( 10 );
      num.addActionListener( this );
      c.add( num );

      resultLabel = new JLabel( "Fibonacci value is" );
      c.add( resultLabel );

      result = new JTextField( 15 );
      result.setEditable( false );
      c.add( result );
   }

   public void actionPerformed( ActionEvent e )
   {  
      long number, fibonacciValue;

      number = Long.parseLong( num.getText() );
      showStatus( "Calculating ..." ); 
      fibonacciValue = fibonacci( number );
      showStatus( "Done." );   
      result.setText( Long.toString( fibonacciValue ) );
   }
  
   // Recursive definition of method fibonacci
   public long fibonacci( long n )
   {
      if ( n == 0 || n == 1 )  // base case
         return n;
      else
         return fibonacci( n - 1 ) + fibonacci( n - 2 );
   }
}

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 * (C) Copyright 1999 by Deitel & Associates, Inc. and Prentice Hall.     *
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