Where should I place the unknown '}' ?

import java.text.*;
import javax.swing.JLabel;
import java.awt.BorderLayout;
import java.awt.*;
import java.awt.event.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.border.TitledBorder;
public class PizzaOrderForm extends JFrame implements ActionListener {
    double sizeCost, toppingCost, amount;
    String msg = "";
    JButton B,B1;
    JLabel L, L1, L2,L3,L4,L5,L6,L7,L8;
    JRadioButton RB,RB1,RB2;
    ButtonGroup buttonGroup = new ButtonGroup();
    JCheckBox C,C1,C2,C3,C4,C5;
    DecimalFormat twoDigits;

    public PizzaOrderForm()
   {
    JPanel panel = new JPanel();
    L = new JLabel("MAMA MIA PIZZARIA");
    L.setSize(500,600);
    L.setFont(new Font("Serif",Font.BOLD,30));
    panel.add(L);
    add(panel,BorderLayout.NORTH);
    
    JPanel panel1 = new JPanel();
    panel1.setLayout(new GridLayout(4,2));
    L1 = new JLabel("Small:");
    L2 = new JLabel("$4.99");
    L3 = new JLabel("Medium:");
    L4 = new JLabel("$6.99");
    L5 = new JLabel("Large:");
    L6 = new JLabel("$8.99");
    L7 = new JLabel("Toppings:");
    L8 = new JLabel("$0.50 each");
    panel1.add(L1);
    panel1.add(L2);
    panel1.add(L3);
    panel1.add(L4);
    panel1.add(L5);
    panel1.add(L6);
    panel1.add(L7);
    panel1.add(L8);
    add(panel1,BorderLayout.WEST);
    
    JPanel panel2 = new JPanel();
    panel2.setLayout(new GridLayout(4,1));
    TitledBorder T = new TitledBorder("Size");
    RB = new JRadioButton("Small");
    RB1 = new JRadioButton("Medium");
    RB2 = new JRadioButton("Large");
    buttonGroup.add(RB);
    buttonGroup.add(RB1);
    buttonGroup.add(RB2);
    panel2.setBorder(T);
    panel2.add(RB);
    panel2.add(RB1);
    panel2.add(RB2);
    add(panel2,BorderLayout.CENTER);
    
    JPanel panel3 = new JPanel();
    panel3.setLayout(new FlowLayout(FlowLayout.CENTER,1,2));
    B = new JButton("Calculate");
    B1 = new JButton("Exit");
    panel3.add(B);
    panel3.add(B1);
    add(panel3,BorderLayout.SOUTH);
    B.addActionListener(this);
    B1.addActionListener(new ButtonListener());
    
    JPanel panel4 = new JPanel();
    panel4.setLayout(new GridLayout(7,1));
    TitledBorder T1 = new TitledBorder("Toppings");
    C = new JCheckBox("Pepperoni");
    C1 = new JCheckBox("Italian Sausage");
    C2 = new JCheckBox("Pineapple");
    C3 = new JCheckBox("Extra Cheese");
    C4 = new JCheckBox("Green Pepper");
    C5 = new JCheckBox("Olived");
    
    panel4.setBorder(T1);
    panel4.add(C);
    panel4.add(C1);
    panel4.add(C2);
    panel4.add(C3);
    panel4.add(C4);
    panel4.add(C5);
    add(panel4,BorderLayout.EAST);
}

public void actionPerformed(ActionEvent e){

    public double sizeCost() 
    {
        if(RB.isSelected()){ 
        return sizeCost = 4.99; 
        }  
        else if(RB1.isSelected()){  
        return sizeCost = 6.99;   
        }  
        else if(RB2.isSelected()){  
        return sizeCost = 4.99;  
        }
        return sizeCost;
    }
        
    public double toppingCost()
    {
        if(C.isSelected()){ 
            toppingCost += 0.50;
        } 
        else if(C1.isSelected()){ 
            toppingCost += 0.50;
        }
        else if(C2.isSelected()){ 
            toppingCost += 0.50;
        }
        else if(C3.isSelected()){ 
            toppingCost += 0.50;
        }
        else if(C4.isSelected()){ 
            toppingCost += 0.50;
        }
        else if(C5.isSelected()){ 
            toppingCost += 0.50;
        }
        return toppingCost;
    }
public void calculate (double sizeCost, double toppingCost)
{

	amount = sizeCost + toppingCost;
        JOptionPane.showMessageDialog(this, msg+"Total: "+amount); 
        
}

    public static void main(String[]args)
    {
        PizzaOrderForm frame = new PizzaOrderForm();
        frame.setSize(500,300);
        frame.setResizable(false);
        frame.setLocationRelativeTo(null); // center the frame
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}
class ButtonListener implements ActionListener
{
    public void actionPerformed(ActionEvent evt)
    {
       System.exit(0);
    }
}