TemperatureConverterGUI.java

gistfile1.java

// TemperatureConverterGUI.java
// Author: Laurencia Walker-Fooks
// Program last changed: 7 December 2011

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

public class TemperatureConverterGUI extends JFrame
{   
    private JLabel promptLabel;
    private JLabel answerLabel;
    
    private int statusFlag = -1;
    
    private JPanel inputPanel = new JPanel();
    private JPanel answerPanel = new JPanel();
    private JPanel menuPanel = new JPanel();
    
    private JMenu conversionMenu;
    private JMenuBar conversionMenuBar = new JMenuBar();
    
    private JTextField userInputField = new JTextField("",6);
    private JButton conversionButton = new JButton("GO");
    private JLabel instructionLabel = new JLabel("(Select conversion type first.)");
    
    public TemperatureConverterGUI ()
    {
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setLayout(new GridLayout(3, 1));
        
        this.promptLabel = new JLabel("Select conversion type: ",JLabel.LEFT);
        this.menuPanel.add(this.promptLabel);
        
        this.conversionMenu = new JMenu("(no conversion type selected)");
    	this.conversionMenuBar.add(conversionMenu);
        this.menuPanel.add(this.conversionMenuBar);
        this.add(this.menuPanel);
        
        userInputField.setEditable(false);

    	conversionButton.addActionListener(new TemperatureListener());
        
        this.inputPanel.add(this.instructionLabel);
        this.inputPanel.add(this.userInputField);
        this.inputPanel.add(this.conversionButton);
        this.add(this.inputPanel);
        
        this.answerLabel = new JLabel(" ",JLabel.CENTER);
        this.answerPanel.add(this.answerLabel);
        this.add(this.answerPanel);
        
        Container container = getContentPane();
        container.add(answerPanel, BorderLayout.SOUTH);
	
        for (int i = 0; i < 2; i++)
        {
            if (i == 0)
            {
            	JMenuItem aConversion = new JMenuItem("Centigrade To Fahrenheit");
            	aConversion.addActionListener(new TemperatureListener());
            	this.conversionMenu.add(aConversion);
            }
            
            else
            {
            	JMenuItem aConversion = new JMenuItem("Fahrenheit to Centigrade");
            	aConversion.addActionListener(new TemperatureListener());
            	this.conversionMenu.add(aConversion);
            }
         }
        
     }
     
    public boolean isDouble (String input)
    {
    	try
    	{
    		Double.parseDouble(input);
    		return true;
    	}
    	catch (NumberFormatException exception)
    	{
    		return false;
    		//answerLabel.setText("SYSTEM ERROR: Input Numerical Number Please.");
    	}
    }
    
    private class TemperatureListener implements ActionListener
    {
        public void actionPerformed(ActionEvent e) 
        {
            
    		String temp = e.getActionCommand();
        	
        	if (temp == "Centigrade To Fahrenheit")
        	{
            	conversionMenu.setText(e.getActionCommand());
            	statusFlag = 1;
            }
            else if (temp == "Fahrenheit to Centigrade")
            {
            	conversionMenu.setText(e.getActionCommand());
            	statusFlag = 0;
            }
            
            userInputField.setEditable(true);
        	String userInput = userInputField.getText();
        	
        	if (isDouble(userInput) == true)
    		{
    			//boolean isDouble = Double.parseDouble(e.getActionCommand());
    		}
    		else
    		{
    			answerLabel.setText("SYSTEM ERROR: Input Numerical Number Please.");
    			userInputField.setText("");
    			
    		}
        	
        	if (statusFlag == 1)
        	{
        		if (isDouble(userInput) == true)
        		{
        			double celsius = Double.parseDouble(userInput);
            		double fahrenheit = (celsius * 9.0/5.0) + 32;
            		//answerLabel.setText(String.format("%.2f", fahrenheit));
            		answerLabel.setText(String.format("%.2f", celsius) + " degrees Centigrade is " + String.format("%.2f", fahrenheit) + " degrees Fahrenheit.");
        		}
        		else 
        			answerLabel.setText("SYSTEM ERROR: Input Numerical Number Please.");
        	}
        	else if (statusFlag == 0)
        	{
        		if (isDouble(userInput) == true)
        		{
        			double fahrenheit = Double.parseDouble(userInput);
            		double celsius = (fahrenheit - 32.0) * 5.0 / 9.0;
            		//answerLabel.setText(String.format("%.2f", celsius));
            		answerLabel.setText(String.format("%.2f", fahrenheit) + " degrees Centigrade is " + String.format("%.2f", celsius) + " degrees Fahrenheit.");
        		}
        		else 
        			answerLabel.setText("SYSTEM ERROR: Input Numerical Number Please.");
        	}
        }
    }
    
    public static void main (String[] args)
    {
        TemperatureConverterGUI win = new TemperatureConverterGUI();
        win.setTitle("Temperature Converter Window");
        win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        win.pack();
        win.setVisible(true);
    }
}