Tax Calculation

This Java program calculates Goods and Services Tax (GST at 7%), Provincial Sales Tax (PST 7.5% on the subtotal), and the total amount. Two cases are implemented: GST only or GST+PST. Implementation details:

• The Round() function is applied for the purposes of printing only to avoid fractional cents.
• Textboxes are used for data input and output display.
• A drop-down list is used to make a choice of the case desired.
• A calculate button is used to initiate the calculations.

import java.awt.*;
import java.awt.event.*;


class ChoiceExample extends Frame implements ActionListener
{

   Button calculateButton = new Button("Calculate");
   Button cancelButton = new Button("Cancel");
   Choice prefix = new Choice();
   TextField PriceText = new TextField(9);
   TextField taxText = new TextField(9);
   TextField totalText = new TextField(9);

   //constructor

   public ChoiceExample()
   {
      super("Calculate  Your Taxes");

      setLayout(new GridLayout(7,2));

      //Add choices to the choice component

      prefix.add("GST");
      prefix.add("GST AND PST");
      //Put components on frame
      add(new Label("Choose your tax(es): "));
      add(prefix);
      add(new Label("Amount "));
      add(PriceText);
      add(new Label(" "));
      add(new Label(" "));
      add(new Label("Tax Amount: "));
      add(taxText);
      add(new Label("Total Amount: "));
      add(totalText);
      add(new Label(" "));
      add(new Label(" "));

      add(calculateButton);
      add(cancelButton);
      calculateButton.addActionListener(this);
      cancelButton.addActionListener(this);
      //set the size for the frame and display it.
      setSize(300, 400);



      pack();
      show();
}
  public double Round(double A){
        return ((int)(A*100+0.5))/100.00;
}
  public void actionPerformed(ActionEvent event)
{


  String Price = PriceText.getText();

  double amount = Double.parseDouble(Price);
  double fedrate = 0.07;
  double provrate = 0.075;
  double GST = amount * fedrate;
  double PST = provrate * (amount + GST);
  double GSTPST = GST + PST;

  if(prefix.getSelectedItem().equals("GST"))
  {
    double totalamount = amount + GST;
    taxText.setText("" + Round(GST));
    totalText.setText("" + Round(totalamount));
  }
  else if(prefix.getSelectedItem().equals("GST AND PST"))
  {
    double totalamount = amount + GSTPST;
    taxText.setText("" + Round(GSTPST));
    totalText.setText("" + Round(totalamount));
  }

}

}

public class tax1
{
   public static void main(String[] args)
   {
      new ChoiceExample();
   }
}