import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.border.*;

/** Find the largest number in a series -- GUI version.<p>
 *
 * This is a follow-on program to <code>DemoLargestConsole</code>.  
 * It is an example of a <i>GUI application</i>
 * - a program that interacts with the user using a
 *   <i>graphical user interface</i> or GUI.  With a GUI
 * application, a mouse and keyboard are used to interact
 * with a graphical objects presented
 * in a window on the system's display.
 * <p>
 *
 * @see <a href="DemoLargestGUI.java">source code</a>
 * @author Scott MacKenzie, 2002
 * @author Modified by William Soukoreff, 2003
 * @author William Soukoreff, 2012
 */
public class DemoLargestGUI extends JFrame implements ActionListener
{
   public static void main(String[] args)
   {
      // use look and feel for my system (Win32)
      try {
         UIManager.setLookAndFeel(
            UIManager.getSystemLookAndFeelClassName());
      } catch (Exception e) {}

      DemoLargestGUI frame = new DemoLargestGUI();
      frame.setTitle("DemoLargestGUI");
      frame.pack();
      frame.setVisible(true);
   }

   private JTextArea inputArea;
   private JTextArea result;

   public DemoLargestGUI()
   {
      // ----------------------------------
      // construct and configure components
      // ----------------------------------

      inputArea = new JTextArea(5, 30);
      inputArea.setAlignmentX(Component.LEFT_ALIGNMENT);
      inputArea.setBackground(getBackground());
      inputArea.setBorder(new TitledBorder(new EtchedBorder(),
         "Enter numbers..."));

      result = new JTextArea("(result appears here)", 1, 30);
      result.setEditable(false);
      result.setAlignmentX(Component.LEFT_ALIGNMENT);
      result.setBackground(getBackground());
      result.setForeground(new Color(204, 0, 0));
      result.setBorder(new TitledBorder(new EtchedBorder(),
         "Largest number is"));

      JButton findButton = new JButton("Find largest");
     
      // -------------
      // add listeners
      // -------------

      findButton.addActionListener(this);
      addWindowListener(new WindowCloser());

      // ------------------
      // arrange components
      // ------------------

      JPanel p1 = new JPanel();
      p1.setLayout(new BoxLayout(p1, BoxLayout.Y_AXIS));
      p1.add(inputArea);
      p1.add(Box.createRigidArea(new Dimension(0, 10)));
      p1.add(result);
      p1.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));

      JPanel p2 = new JPanel();  // flow layout
      p2.add(findButton);
         
      JPanel contentPane = new JPanel(new BorderLayout());
      contentPane.add(p1, "Center");
      contentPane.add(p2, "South");
      contentPane.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));

      setContentPane(contentPane);
   }

   // -------------------------------
   // implement ActionListener method
   // -------------------------------

   public void actionPerformed(ActionEvent ae)
   {
      String input = inputArea.getText();
      double largest = findLargest(input);
      result.setText("" + largest);
   }

   // -------------
   // other methods
   // -------------

   public static double findLargest(String sArg)
   {
      StringTokenizer st = new StringTokenizer(sArg);

      double result = Double.MIN_VALUE;
      while (st.hasMoreTokens())
      {
         double value = Double.parseDouble(st.nextToken());
         if (value > result)
            result = value;
      }
      return result;
   }

   // -----------
   // inner class
   // -----------

   // Note: WindowAdapter implements windowClosing

   private class WindowCloser extends WindowAdapter
   {
      public void windowClosing(WindowEvent event)
      {
         System.exit(0);
      }
   }
}