Thread: Help With My DormAndMealPlanCalculator Assignment Please?

I've been working on my program for a while and I can't seem to figure it out, since I still consider myself new to the language. Anyways, my professor is looking for the GUI Application to calculate charges when selecting dorms and meals, and when you click the "Calculate" button, you're suppose to get the total charges. Only in my program, when I select either a dorm or meal it calculates the total charges without clicking the button. Can anyone help me out? I'd very much appreciate it. I will also attach a pic on what the expected output my professor is looking for. Thanks.

import java.awt.*;			// Import common GUI elements.
import java.awt.event.*;	// Import common GUI event listeners.
import javax.swing.*;		// Import more common GUI elements.
 
/** DormAndMealPlanCalculator class. */
public class DormAndMealPlanCalculator extends JFrame
{
	private static final long serialVersionUID = 1L;
	private JLabel label;					// Display a message.
	private JPanel dormPanel;				// To hold dorm panel components.
	private JPanel selectedDormPanel;		// To hold selected dorm panel components.
	private JComboBox dormBox;				// List of dorms.
	private JTextField selectedDorm;		// Selected dorm.
	private JPanel mealPanel;				// To hold meal panel components.
	private JPanel selectedMealPanel;		// To hold selected meal panel components.
	private JComboBox mealBox;				// List of meal plans.
	private JTextField selectedMeal;		// Selected meal plan.
	private JButton calcButton;				// To hold total panel component.
	private JTextField total;				// Total plan.
 
	/** Array to hold the values of the dormitory
	    combo box. */
	private String[] dorm =
		{
			"Allen Hall $" + 1500, "Pike Hall $" + 1600, 
			"Farthing Hall $" + 1200, "University Suites $" + 1800
		};
 
	/** Array to hold the dormitory rate. */
	double[] dRate = {1500, 1600, 1200, 1800};
 
	/** Array to hold the values of the meal
	    combo box. */
	private String[] meal =
		{
			"7 Meals Per Week $" + 560,
			"14 Meals Per Week $" + 1095,
			"Unlimited Meals $" + 1500
		};
 
	/** Array to hold the meal plan rate. */
	double[] mRate = {560, 1095, 1500};
 
	/** Constructor. */
	public DormAndMealPlanCalculator()
	{
		setTitle("Dorm and Meal Plan Calculator.");			// Set the title.
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);		// Specify action for close button.
		setLayout(new GridLayout(3,2));						// Create a border layout manager.
 
		// Build panels.
		buildDormPanel();
		buildMealPanel();
		buildTotalPanel();
 
		// Add panels to content pane.
		add(dormPanel);
		add(mealPanel);
		add(calcButton);
 
		// Pack and display.
		pack();
		setVisible(true);
	}
 
	/** buildDormPanel function that adds a combo box
	    with the dormitories to the panel. */
	private void buildDormPanel()
	{
		dormPanel = new JPanel();		// Create panel to hold combo box.
		dormBox = new JComboBox(dorm);	// Create the combo box.
 
		// Register an action listener. 
		dormBox.addActionListener(new ComboBoxListener());
		dormPanel.add(dormBox);
	}
 
 
	/** buildMealPanel function that adds a combo box
	    with the types of meals to the panel. */
	private void buildMealPanel()
	{
		mealPanel = new JPanel();		// Create panel to hold combo box.
		mealBox = new JComboBox(meal);	// Create the combo box.
 
		// Register an action listener.
		mealBox.addActionListener(new ComboBoxListener());
		mealPanel.add(mealBox);
	}
 
	/** buildSelectedDormPanel function adds a
	    read-only text field to the panel. */
	public void buildSelectedDormPanel()
	{
		selectedDormPanel = new JPanel();			// Create panel to hold components.
		label = new JLabel("Your Dormitory Is: ");	// Create the label.
 
		// Create the uneditable text field.
		selectedDorm = new JTextField(20);
		selectedDorm.setEditable(false);
 
		// Add the label and text field
		// to the panel.
		selectedDormPanel.add(label);
		selectedDormPanel.add(selectedDorm);
	}
 
	/** buildSelectedMealPanel function adds a
	    read-only text field to the panel. */
	public void buildSelectedMealPanel()
	{
		selectedMealPanel = new JPanel();			// Create panel to hold components.
		label = new JLabel("Your Meal Plan Is: ");	// Create the label.
 
		// Create the uneditable text field.
		selectedMeal = new JTextField(20);
		selectedMeal.setEditable(false);
 
		// Add the label and text field
		// to the panel.
		selectedMealPanel.add(label);
		selectedMealPanel.add(selectedMeal);
	}
 
	/** buildTotalPanel function adds a
	  read-only text field to the panel. */
	private void buildTotalPanel()
	{
		calcButton = new JButton("Calculate");
 
		// Create the uneditable text field.
		total = new JTextField(15);
		total.setEditable(false);
	}
 
	/** Private inner class that handles the event when the
	    user selects an item from the combo box. */
	private class ComboBoxListener implements ActionListener
	{
		public void actionPerformed(ActionEvent e)
		{
			// Declare variables.
			int dorm;
			int meal;
			double total1;		// String total.
 
			// Get the selected dormitory.
			dormBox.getSelectedItem();
			dorm = dormBox.getSelectedIndex();
 
			// Get the selected meal plan.
			mealBox.getSelectedItem();
			meal = mealBox.getSelectedIndex();
 
			// Add the selections.
			total1 = dRate[dorm] + mRate[meal];
			total.setText("$" + total1);
 
			JOptionPane.showMessageDialog(null, "Total Charges Per Semester: " + total1);
		}
	}
 
	/** Main function. */
	public static void main(String[] args) 
	{
		new DormAndMealPlanCalculator();
	}
 
}

Did you write this? If you had written it, it seems you'd know that the ComboBoxListener class computes and displays the total when a change is detected in a combo box. Knowing that (as you should), you might be able to modify what you'd written to change the action to a listener on the calculate button.

Originally Posted by GregBrannon

Did you write this? If you had written it, it seems you'd know that the ComboBoxListener class computes and displays the total when a change is detected in a combo box. Knowing that (as you should), you might be able to modify what you'd written to change the action to a listener on the calculate button.

Of course I've written it, I've been working on it for the past week or two. Not to mention I have the book, but understanding this button stuff is difficult to grasp for me.

Originally Posted by Ada Lovelace

Have you debugged it step by step? Try setting a breakpoint where you think
(or want) the program to terminate. Also, set the debugger so it shows you
how values change with each executable step. If you place a breakpoint in the wrong
place, you can either continue debugging past that point or step out of the code.

It looks like a logical error - and the debugger is a good tool to aid you in this.

Wishes Ada xx

No I haven't done that yet to be honest, thanks for the reminder of that.

Originally Posted by Norm

If converting the code is giving you problems, perhaps another approach would help.
Write a small simple program with a frame, a button and a listener for that button. Put a call to JOptionPane in the button's listener so you know its been called. If you have problems with it, copy and paste it here and describe your problems.
When you get it to work, you should see how to use a button with a listener.

I'll try that, thanks.

Of course I've written it, I've been working on it for the past week or two.

You have the code you need to make your program do what you you've described, but you have it in the wrong place. To make the necessary changes, here are 3 simple steps:

1. Comment out the statement that adds the ComboBoxListener to the dormBox,
2. Comment out the statement that adds the ComboBoxListener to the mealBox, and
3. Add a statements that adds the ComboBoxListener to the computeButton.

Then it will work as you've described. You may want to then do some cleanup, change the name of the ActionListener class, delete lines that you've commented out, etc., but that's purely up to you.

Okay I have it working correctly, but I feel it could use a touch up. I'm trying to add the width and height of the buttons but after putting it in different areas of the code, it doesn't seem to work. I have the variables declared and I tried using

setSize(width, height);

within the button coding but no luck. What am I missing? It's gotta be something simple.

import java.awt.*;						// Needed for BorderLayout.
import javax.swing.*;					// Import more common GUI elements.
import java.awt.event.ActionEvent; 		// Needed for an action on a component.
import java.awt.event.ActionListener;	// ActionListener interface can receive ActionEvent objects.
import java.text.DecimalFormat;			// Needed for a custom output.
 
/** DormAndMealPlanCalculator class. */
public class DormAndMealPlanCalculator extends JFrame
{
	private static final long serialVersionUID = 1L;
	private JLabel label;					// Display a message.
	private JPanel dormPanel;				// To hold dorm panel components.
	private JPanel selectedDormPanel;		// To hold selected dorm panel components.
	private JComboBox dormBox;				// List of dorms.
	private JTextField selectedDorm;		// Selected dorm.
	private JPanel mealPanel;				// To hold meal panel components.
	private JPanel selectedMealPanel;		// To hold selected meal panel components.
	private JComboBox mealBox;				// List of meal plans.
	private JTextField selectedMeal;		// Selected meal plan.
	private JButton calcButton;				// To calculate the total charges.
	private JButton exitButton;				// To exit and close the program.
	private JTextField total;				// Total text.
	private int width = 400;
	private int height = 200;
 
	/** Allocate memory to hold the values 
	    of the dormitory combo box. */
	private String[] dorm =
		{
			"Farthing Hall $" + 1200, "Allen Hall $" + 1500, 
			"Pike Hall $" + 1600, "University Suites $" + 1800
		};
 
	/** Allocate memory to hold the dormitory rate. */
	double[] dRate = {1200, 1500, 1600, 1800};
 
	/** Allocate memory to hold the values 
	    of the meal combo box. */
	private String[] meal =
		{
			"7 Meals Per Week $" + 560,
			"14 Meals Per Week $" + 1095,
			"Unlimited Meals $" + 1500
		};
 
	/** Allocate memory to hold the meal plan rate. */
	double[] mRate = {560, 1095, 1500};
 
	/** Constructor. */
	public DormAndMealPlanCalculator()
	{
		setTitle("Dorm and Meal Plan Calculator.");			// Set the title.
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);		// Specify action for close button.
		setLayout(new GridLayout(3,2));						// Create a border layout manager.
 
		// Build panels.
		buildDormPanel();
		buildMealPanel();
		buildTotalPanel();
 
		// Add panels to content pane.
		add(dormPanel);
		add(mealPanel);
		add(calcButton);
		add(exitButton);
 
		// Pack and display.
		pack();
		setVisible(true);
	}
 
	/** buildDormPanel function that adds a combo box
	    with the dormitories to the panel. */
	private void buildDormPanel()
	{
		dormPanel = new JPanel();		// Create panel to hold combo box.
		dormBox = new JComboBox(dorm);	// Create the combo box.
 
		// Register an action listener. 
		dormBox.addActionListener(new ComboBoxListener());
		dormPanel.add(dormBox);
	}
 
 
	/** buildMealPanel function that adds a combo box
	    with the types of meals to the panel. */
	private void buildMealPanel()
	{
		mealPanel = new JPanel();		// Create panel to hold combo box.
		mealBox = new JComboBox(meal);	// Create the combo box.
 
		// Register an action listener.
		mealBox.addActionListener(new ComboBoxListener());
		mealPanel.add(mealBox);
	}
 
	/** buildSelectedDormPanel function adds a
	    read-only text field to the panel. */
	public void buildSelectedDormPanel()
	{
		selectedDormPanel = new JPanel();			// Create panel to hold components.
		label = new JLabel();						// Create the label.
 
		// Create the uneditable text field.
		selectedDorm = new JTextField(20);
		selectedDorm.setEditable(false);
 
		// Add the label and text field
		// to the panel.
		selectedDormPanel.add(label);
		selectedDormPanel.add(selectedDorm);
	}
 
	/** buildSelectedMealPanel function adds a
	    read-only text field to the panel. */
	public void buildSelectedMealPanel()
	{
		selectedMealPanel = new JPanel();			// Create panel to hold components.
		label = new JLabel();						// Create the label.
 
		// Create the uneditable text field.
		selectedMeal = new JTextField(20);
		selectedMeal.setEditable(false);
 
		// Add the label and text field
		// to the panel.
		selectedMealPanel.add(label);
		selectedMealPanel.add(selectedMeal);
	}
 
	/** buildTotalPanel function adds a
	  read-only text field to the panel. */
	private void buildTotalPanel()
	{
		calcButton = new JButton("Calculate Charges");
		calcButton.addActionListener(new calcButtonListener());
 
		exitButton = new JButton("Exit");
		exitButton.addActionListener(new exitButtonListener());
 
		// Create the uneditable text field.
		total = new JTextField(15);
		total.setEditable(false);
	}
 
	/** Private inner class that handles the event when the
	    user selects an item from the combo box. */
	private class ComboBoxListener implements ActionListener
	{
		public void actionPerformed(ActionEvent e)
		{
			// Declare variables.
			int dorm;
			int meal;
			double total1;		// String total.
 
			// Get the selected dormitory.
			dormBox.getSelectedItem();
			dorm = dormBox.getSelectedIndex();
 
			// Get the selected meal plan.
			mealBox.getSelectedItem();
			meal = mealBox.getSelectedIndex();
 
			// Add the selections.
			total1 = dRate[dorm] + mRate[meal];
			total.setText("$" + total1);
		}
	}
 
	/** Private inner class that handles the total event when the
	    user selects the calculate button. */
	private class calcButtonListener implements ActionListener
	{
		public void actionPerformed(ActionEvent e)
		{		
			// Declare variables.
			int dorm;
			int meal;
			double total2;		// String total.
 
			// Create a dollar object.
			DecimalFormat dollar = new DecimalFormat("0.00");
 
			// Get the selected dormitory.
			dormBox.getSelectedItem();
			dorm = dormBox.getSelectedIndex();
 
			// Get the selected meal plan.
			mealBox.getSelectedItem();
			meal = mealBox.getSelectedIndex();
 
			// Add the selections.
			total2 = dRate[dorm] + mRate[meal];
			total.setText("$" + total2);
 
			// Display the total charges in a separate window.
			JOptionPane.showMessageDialog(null, "Total Chargers Per Semester: $" + dollar.format(total2));
		}
	}
 
	/** Private inner class that handles the exit event when the
	    user selects the exit button. */
	private class exitButtonListener implements ActionListener
	{
		public void actionPerformed(ActionEvent e)
		{
			// Close the box.
			System.exit(0);
		}
	}
 
	/** Main function. */
	public static void main(String[] args) 
	{
		new DormAndMealPlanCalculator();
	}
 
}

You dont set the size of components. You never do that.
The sizes of components, as well as their positions, are determined by the layout manager used in their parent.
Pick the right layout manager for the parent and use the preferredSize of the component if need be.

Originally Posted by Cornix

You dont set the size of components. You never do that.
The sizes of components, as well as their positions, are determined by the layout manager used in their parent.
Pick the right layout manager for the parent and use the preferredSize of the component if need be.

Gotcha. Thanks for the tip.