//********************************************************************
//  Fahrenheit.java       Author: Lewis/Loftus
//
//  Demonstrates the use of JFrame and JTextArea GUI components.
//********************************************************************

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

public class Fahrenheit
{
  Fahrenheit()
  {
    FahrenheitGUI converter = new FahrenheitGUI();
    converter.display();
  }
  
  class FahrenheitGUI
  {
    private int WIDTH = 300;
    private int HEIGHT = 75;

    private JFrame frame;
    private JPanel panel;
    private JLabel inputLabel, outputLabel, resultLabel;
    private JTextField fahrenheit;

    //-----------------------------------------------------------------
    //  Sets up the GUI.
    //-----------------------------------------------------------------
    public FahrenheitGUI()
    {
      frame = new JFrame ("Temperature Conversion");
      frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);

      inputLabel = new JLabel ("Enter Fahrenheit temperature:");
      outputLabel = new JLabel ("Temperature in Celcius: ");
      resultLabel = new JLabel ("---");

      fahrenheit = new JTextField (5);
      fahrenheit.addActionListener (new TempListener());

      panel = new JPanel();
      panel.setPreferredSize (new Dimension(WIDTH, HEIGHT));
      panel.setBackground (Color.yellow);
      panel.add (inputLabel);
      panel.add (fahrenheit);
      panel.add (outputLabel);
      panel.add (resultLabel);

      frame.getContentPane().add (panel);
    }

    //-----------------------------------------------------------------
    //  Displays the primary application frame.
    //-----------------------------------------------------------------
    public void display()
    {
      frame.pack();
      frame.show();
    }

    //*****************************************************************
    //  Represents an action listener for the temperature input field.
    //*****************************************************************
    private class TempListener implements ActionListener
    {
      //--------------------------------------------------------------
      //  Performs the conversion when the enter key is pressed in
      //  the text field.
      //--------------------------------------------------------------
      public void actionPerformed (ActionEvent event)
      {
        int fahrenheitTemp, celciusTemp;

        String text = fahrenheit.getText();

        fahrenheitTemp = Integer.parseInt (text);
        celciusTemp = (fahrenheitTemp-32) * 5/9;

        resultLabel.setText (Integer.toString (celciusTemp));
      }
    }
  }

  //-----------------------------------------------------------------
  //  Creates and displays the temperature converter GUI.
  //-----------------------------------------------------------------
  public static void main (String[] args)
  {
    new Fahrenheit();
  }
}