AWT - Basic temperature conversion

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

class MyFrame extends Frame
{
    public MyFrame(String title)
    {
        super(title);
        setLayout(new GridLayout(2,2));
    //setLocationRelativeTo(null);

    Dimension dim = getToolkit().getScreenSize();
    int screenWidth = dim.width;
    int screenHeight = dim.height;

    setLocation((screenWidth-100)/2,(screenHeight-170)/2);
        setSize(170,100);
        setVisible(true);
        setResizable(false);

    Label lc = new Label("Celsius");
        add(lc);

        TextField cel = new TextField(40);
        add(cel);

        Label lf = new Label("Fahrenheit");
        add(lf);

        TextField fah = new TextField(40);
        add(fah);

        cel.addActionListener(new TempListener(cel,fah,this));
        fah.addActionListener(new TempListener(cel,fah,this)); //Fahrenheit

        addWindowListener(new WindowClose());


    }
}

class TempListener extends Component implements ActionListener
{
    TextField fah,cel;
    Frame f;
    public TempListener(TextField cel, TextField fah,Frame f)
    {
        this.fah=fah;
        this.f=f;
        this.cel=cel;
    }

    public void actionPerformed(ActionEvent ae)
    {

        try
        {
            Object source = ae.getSource();
            String text;
            double originalValue;
            double convertedValue;

            if(source==cel)
            {
                text=cel.getText();
                originalValue = Double.parseDouble(text);
                convertedValue=((originalValue*(9.0/5.0)+32));
                fah.setText(" " + convertedValue);
            }
            else
            {
                text=fah.getText();
                originalValue = Double.parseDouble(text);
                convertedValue = (originalValue-32)*(5.0/9.0);
                cel.setText(" "+ convertedValue);
            }
        }
        catch(Exception e)
    {
        JOptionPane.showMessageDialog(f,"Error: " +e.getMessage() + "\n\nTry entering again", "Input error", JOptionPane.ERROR_MESSAGE);
        cel.setText("");
        fah.setText("");
    }
    }
}

class WindowClose extends WindowAdapter
{
    public void windowClosing(WindowEvent we)
    {
        System.exit(0);
    }
}

public class Temperature
{
    public static void main(String args[])
    {
        Frame f = new MyFrame("C-F");
    }
}