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

//to allow use of message box
import javax.swing.JOptionPane;
//to allow use of ActionListener
import java.awt.event.*;




class GUIExample1 extends JFrame implements ActionListener{
    
    //define interface components
    JLabel numberLabel, numberLabel2;
    JTextField numberPriceField, numberDiscountField;
    JButton displayButton;
    
    public GUIExample1(){
        
    Container pane = getContentPane();
    pane.setLayout(new GridLayout (3, 2, 2, 2));
    numberLabel = new JLabel ("Price: ");
    numberPriceField = new JTextField (10);
    numberLabel2 = new JLabel("Discount");
    numberDiscountField = new JTextField (10);
    displayButton = new JButton ("Calculate");
    
    pane.add(numberLabel);
    pane.add(numberPriceField);
    pane.add(numberLabel2);
    pane.add(numberDiscountField);
    pane.add(displayButton);
    displayButton.addActionListener(this);
    
    
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setTitle ("CALCULATE PRICE AFTER DISCOUNT");
    pack();
    show();
    
    }
    
    
    public static void main (String[] args){
        new GUIExample1();
    }
    
    public void actionPerformed(ActionEvent event){
        Object source = event.getSource();
        
    if (source == displayButton){
        
        try{
            
        double price = Double.parseDouble(numberPriceField.getText());
        double discount = Double.parseDouble(numberDiscountField.getText());
        double result =price-((discount/100)*price);
        JOptionPane.showMessageDialog(null, "Price after discount is RM" +(result),
                                      "Hello", JOptionPane.PLAIN_MESSAGE);
        System.exit(0);
    }
        catch (Exception e){
        JOptionPane.showMessageDialog(null, "You have entered an invalid value. Please enter number", "ERROR",
        JOptionPane.PLAIN_MESSAGE);
    }
    
    }

}
}