import java.swing.*;

public class CurrencyConverter
{
	public static void main(String[] args)
	{
		String currencyTo;
		String currencyFrom;
		String input;
		double amount = 0;
		double newAmount = 0;
		double CADtoUSD;
		double USDtoCAD;
		boolean done = false;
		

		while(!done)
		{	
			//get the currency to which we will be converting
			currencyTo = JOptionPane.showInputDialog("Enter the currency you are converting to - type either CAD or USD:);

			if(currencyTo != null)
			{
				while(!currencyTo.equals("CAD") && !currency.equals("USD"))
				{
					currencyTo = JOptionPane.showInputDialog("Enter a currency - type either CAD or USD:);	
				}

				//get the current rate
				if(currencyTo.equals("CAD"))
				{
					input = JOptionPane.showInputDialog("Enter the current USD to CAD conversion rate");

					if(input != null)
					{
						USDtoCAD = Double.parseDouble(input);
					}
				}
				else   //currency has to be USD or program won't have gotten past the above while loop
				{
					input = JOptionPane.showInputDialog("Enter the current CAD to USD conversion rate");

					if(input != null)
					{
						CADtoUSD = Double.parseDouble(input);
					}
				}

				//get an amount to convert
				input = JOptionPane.showInputDialog("Enter the dollar amount, in decimal, to be converted.");

                                while(input == null || amount < 0)
				{
					input = JOptionPane.showInputDialog("Enter the dollar amount, in decimal, to be converted.");
                                        if(input != null)
                                        {
                                            amount = Double.parseDouble(input);
                                        }
				}

				//perform the conversion
				if(currencyTo.equals("CAD"))
				{
					newAmount = amount * USDtoCAD;
					currencyFrom = "USD";
				}
				else
				{
					newAmount = amount * CADtoUSD;
					currencyFrom = "CAD";
				}

				//print the result
				JOptionPane.showMessageDialog("$" + amount + " " + currencyFrom + " = $" + newAmount + " " + currencyTo);
			}
			else
			{
				done = true;
			}
		}
	}
}