import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
 
/*
An applet to convert celsius to Fahrenheit and vide-versa
*/
 
public class CFConversion extends JApplet implements ActionListener{
	private JTextField cText = new JTextField(15);
	private JTextField fText = new JTextField(15);
 
	public void init(){
		JPanel panel = new JPanel();
		panel.setLayout(new GridLayout (2,2)) ;
		panel.add ( new JLabel("Celsius:") ) ;
		panel.add ( cText ) ;
		panel.add ( new JLabel("Fahrenheit:") ) ;
		panel.add ( fText ) ;
		cText.addActionListener ( this ) ;
		fText.addActionListener ( this ) ;
		this.getContentPane().add (panel, "North");
	}
 
	public void actionPerformed(ActionEvent e ) {
		double c = 0.0;
		double f = 0.0;
		if ( e.getSource () == cText ) {
			 try {
				if ( cText.getText().equals("")){
					// Clear the F text
					fText.setText("");
				}
				else {
					c = Double.parseDouble(cText.getText());
					f = CtoF(c);
					fText.setText(Double.toString(f));
				}
			 }
			catch(NumberFormatException e1) {
			  // Just clear both fields
			 clearFields();
			}
		}
		else if ( e.getSource() == fText) {
			 try {
				if ( fText.getText().equals("")){
					// Clear the C text
					cText.setText("");
				}
				else {
					f = Double.parseDouble(fText.getText());
					c = FtoC(f);
					cText.setText(Double.toString(c));
				}
			 }
			catch(NumberFormatException e2) {
			  // Just clear both fields
			 clearFields();
			}
 
		}
	}
 
	public double CtoF(double c) {
		return (9.0/5.0) * c + 32.0;
	}
 
	public double FtoC(double f) {
		return  (5.0/9.0) * (f - 32.0);
	}
	public void clearFields(){
		cText.setText("");
		fText.setText("");
	}
 
 
	public static void main(String[] args) {
		JFrame f = new JFrame();
		CFConversion cf = new CFConversion();
		cf.init();
		f.getContentPane().add (cf);
		f.pack();
		f.setVisible ( true);
	}
}