Question

Basically what this simple program does is
display the summary when you click on the button,
There are three radio buttons for the pizza sizes, and three checkboxes for the toppings.
The problem I’m having is when the user first click on a topping, then after clicking the button and displaying the appropriate summary in a MessageDialog, when the users wants to have no toppings, it won’t display the “No Toppings Selected”

import java.applet.Applet;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.*;
import javax.swing.*;

public class PizzaOrdering extends Applet implements ActionListener, ItemListener {

    Button btnOk = new Button("OK");
    CheckboxGroup cbgSize = new CheckboxGroup();
    Checkbox chkSmall = new Checkbox("Small", cbgSize, false);
    Checkbox chkMedium = new Checkbox("Medium", cbgSize, false);
    Checkbox chkLarge = new Checkbox("Large", cbgSize, false);
    Checkbox chkPep = new Checkbox("Pepperoni");
    Checkbox chkMush = new Checkbox("Mushroom");
    Checkbox chkAnch = new Checkbox("Anchiovies");
    String pizza = "";
    String topping1 = "";
    String topping2 = "";
    String topping3 = "";
    String others = "with no toppings";
    Label lbl1 = new Label("Size");
    Label lbl2 = new Label("Toppings");
    Label spacer = new Label("                                                ");
    Label spacer2 = new Label("                                                ");

    @Override
    public void init() {
        resize(250, 150);
        add(lbl1);
        add(spacer);
        add(chkSmall);
        add(chkMedium);
        add(chkLarge);
        add(lbl2);
        add(spacer2);
        add(chkPep);
        add(chkMush);
        add(chkAnch);
        add(btnOk);
        chkAnch.addItemListener(this);
        chkPep.addItemListener(this);
        chkMush.addItemListener(this);
        btnOk.addActionListener(this);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == btnOk) {
            if (cbgSize.getSelectedCheckbox() == chkSmall) {
                pizza = "Small";
            }
            if (cbgSize.getSelectedCheckbox() == chkMedium) {
                pizza = "Medium";
            }
            if (cbgSize.getSelectedCheckbox() == chkLarge) {
                pizza = "Large";
            }
            JOptionPane.showMessageDialog(btnOk, "You ordered a " + 
                    pizza + " pizza " + others, "Your Order", WIDTH);
        }
    }

    @Override
    public void itemStateChanged(ItemEvent ex) {
        boolean state1 = false;
        boolean state2 = false;
        boolean state3 = false;
        if (ex.getItemSelectable() == chkMush) {
            state1 = chkMush.getState();
            if (state1 == true) {
                topping1 = "Mushroom";
            } else if (state1 == false) {
                topping1 = "";
                if (state2 == false && state3 == false) {
                    others = "with no toppings";
                }
            }
        }

        if (ex.getItemSelectable() == chkPep) {
            state2 = chkPep.getState();
            if (state2 == true) {
                topping2 = "Pepperoni";
            } else if (state2 == false) {
                topping2 = "";
                if (state1 == false && state3 == false) {
                    others = "with no toppings";
                }
            }
        }

        if (ex.getItemSelectable() == chkAnch) {
            state3 = chkAnch.getState();
            if (state3 == true) {
                topping3 = "Anchiovies";

            } else if (state3 == false) {
                topping3 = "";
                if (state1 == false && state2 == false) {
                    others = "with no toppings";
                }
            }
        }
        others = " with the following topping:" + 
                topping1 + " " + topping2 + " " + topping3;
    }
}

Answer 1

The itemStateChanged method is not even called when the user does not check or uncheck any of the checkboxes. So put the “No topping selected” label visible by default and hide or remove it in the itemStatechanged method whenever some topping has been selected. You can use a static int field ‘count’ in your itemStateChanged method and increment it on every topping selected and decrement on every topping deselected.

In this way, for every deselection, decrease count by one and check count, if it is zero, just set that label with “no topping selected” visible or reappear.