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#1 joshklewis  Icon User is offline

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Displaying Variables to Gui

Posted 10 September 2010 - 11:28 PM

I am a Java student and I am working on an assignment for class. This is my first program that implements a GUI. It is a simple program for inventory. It has several classes for the CD object (The inventory is for cds), RockBand (subclass of CD), AlbumNameComparator (to sort array of cds), and classes that are suppose to show the GUI. I can get the main frame to show, but the label frame, text frame, and button frame are not showing, and I cannot figure out why. I have compared the examples given in the text and from the instructor, but cannot locate my problem. Can someone help? Here is what I have so far:

 * Program: Inventory Program Part 4
 * File: InventoryFrame.java
 * Summary: Inherits JFrame class to build a window application that
 *          contains label and text fields.
 * Author: Joshua Lewis
 * Date: September 10, 2010
package inventoryprogrampart4;

import java.awt.GridLayout; //Import to create grid layout
import java.awt.BorderLayout; //Import to create border layout
import java.awt.event.ActionEvent; //Import for click events
import java.awt.event.ActionListener; //Import for click events
import javax.swing.JPanel; //Import to create panels
import javax.swing.JFrame; //Import to use frame
import javax.swing.JButton; //Import to create buttons
import javax.swing.JLabel; //Import to create text fields
import javax.swing.JTextField; //Import to create text fields
import java.util.Arrays; //Import to use arrays

public class InventoryFrame extends JFrame { //Begin InventoryFrame Class

    //Declare two panels. gridPanel is main panel. panel is inserted into gridPanel
    private JPanel gridPanel = new JPanel();
    private JPanel panel = new JPanel();
    //Declare buttons
    JButton nextButton; //Button to go to next page
    //Declare text fields
    JTextField itemNumberField; //Field for itemNumber
    JTextField bandNameField; //Field for bandName
    JTextField albumNameField; //Field for albumName
    JTextField stockUnitsField; //Field for stockUnits
    JTextField priceField; //Field for pricePerItem
    JTextField totalValueField; //Field for totalInventoryValue
    //Declare labels
    JLabel lblItemNumber; //Label for itemNumber
    JLabel lblBandName; //Label for bandName
    JLabel lblAlbumName; //Label for albumName
    JLabel lblStock; //Label for stockUnits
    JLabel lblPrice; //Label for pricePeritem
    JLabel lblValue; //Label for totalInventoryValue
    //Declare five RockBand Objects
    RockBand band1;
    RockBand band2;
    RockBand band3;
    RockBand band4;
    RockBand band5;
    public static int MAX_CDS = 5; //Set maximum size for cds array
    public RockBand cds[] = new RockBand[MAX_CDS]; //Declare array of RockBand objects
    static int ArrayIndex = 0; //Declare array index

    public void InventoryFrame() { //Begin Constructor

        //Create and initialize five RockBand objects
        band1 = new RockBand();
        band1.setBandName("Lamb of God"); //Sets bandName for band1
        band1.setAlbumName("New American Gospel"); //Sets albumName for band1
        band1.setItemNumber("606-001"); //Sets itemNumber for band1
        band1.setPrice(9.99); //Sets pricePerItem for band1
        band1.setUnits(6); //Sets numberOfUnitsInStock for band1

        band2 = new RockBand();
        band2.setBandName("Lamb of God"); //Sets bandName for band2
        band2.setAlbumName("As the Palaces Burn"); //Sets albumName for band2
        band2.setItemNumber("606-002"); //Sets itemNumber for band2
        band2.setPrice(10.99); //Sets pricePerItem for band2
        band2.setUnits(4); //Sets numberOfUnitsInStock for band2

        band3 = new RockBand();
        band3.setBandName("Lamb of God"); //Sets bandName for band3
        band3.setAlbumName("Ashes of the Wake"); //Sets albumName for band3
        band3.setItemNumber("606-003"); //Sets itemNumber for band3
        band3.setPrice(11.99); //Sets pricePerItem for band3
        band3.setUnits(9); //Sets numberOfUnitsInStock for band3

        band4 = new RockBand();
        band4.setBandName("Lamb of God"); //Sets bandName for band4
        band4.setAlbumName("Sacrament"); //Sets albumName for band4
        band4.setItemNumber("606-004"); //Sets itemNumber for band4
        band4.setPrice(14.99); //Sets pricePerItem for band4
        band4.setUnits(14); //Sets numberOfUnitsInStock for band4

        band5 = new RockBand();
        band5.setBandName("Lamb of God"); //Sets bandName for band5
        band5.setAlbumName("Wrath"); //Sets albumName for band5
        band5.setItemNumber("606-005"); //Sets itemNumber for band5
        band5.setPrice(14.99); //Sets pricePerItem for band5
        band5.setUnits(12); //Sets numberOfUnitsInStock for band5

        //Add RockBand objects to cds array
        cds[0] = band1; //Assigns band1 to first space in array
        cds[1] = band2; //Assigns band2 to second space in array
        cds[2] = band3; //Assigns band3 to third space in array
        cds[3] = band4; //Assigns band4 to fourth space in array
        cds[4] = band5; //Assigns band5 to fifth space in array

        gridPanel.setLayout(new BorderLayout()); //Create a border layout

        gridPanel.add(this.createLabelPanel(), BorderLayout.WEST); //Add label panel
        gridPanel.add(this.createTextPanel(), BorderLayout.CENTER); //Add text panel
        gridPanel.add(this.createButtonPanel(), BorderLayout.SOUTH); //Add button panel

        //Parameters for sort are the cds array and AlbumNameComparator
        Arrays.sort(cds, new AlbumNameComparator()); //Sort cds array

    } //End constructor

    //Method to create panel for button
    private JPanel createButtonPanel() { //Begin createButtonPanel method

        ActionListener btnListen = new ButtonListener(); //Create listener

        //Create button objects
        nextButton = new JButton("Display CD"); //Create and label button
        nextButton.setActionCommand("Next"); //Set action command for click button event
        nextButton.addActionListener(btnListen); //Button listener for click button event

        //Create panel object
        JPanel panel = new JPanel();

        panel.add(nextButton); //Add next button to panel

        return panel;
    } //End createButtonPanel method

    private JPanel createLabelPanel() { //Begin createLabelPanel method
        //Create instance of label objects
        lblItemNumber = new JLabel("Item Number:"); //Label for itemNumber
        lblBandName = new JLabel("Band Name:"); //Label for bandName
        lblAlbumName = new JLabel("Album Name:"); //Label for albumName
        lblPrice = new JLabel("Price Per Item:"); //Label for pricePerItem
        lblStock = new JLabel("Number In Stock:"); //Label for stockUnits
        lblValue = new JLabel("Total Inventory Value:"); //Label for totalInventoryValue

        panel = new JPanel();
        panel.setLayout(new GridLayout(5, 1));

        //Add labels to panel

        return panel;
    } //End createLabelPanel method

    private JPanel createTextPanel() { //Begin createTextPanel method
        //Create instances of text box objects
        itemNumberField = new JTextField(); //Field for itemNumber
        itemNumberField.setEditable(false); //Set field not editable

        bandNameField = new JTextField(); //Field for bandName
        bandNameField.setEditable(false); //Set field not editable

        albumNameField = new JTextField(); //Field for albumName
        albumNameField.setEditable(false); //Set field not editable

        stockUnitsField = new JTextField(); //Field for stockUnits
        stockUnitsField.setEditable(false); //Set field not editable

        priceField = new JTextField(); //Field for pricePerItem
        priceField.setEditable(false); //Set field not editable

        totalValueField = new JTextField(); //Field for totalInventoryValue
        totalValueField.setEditable(false); //Set field not editable

        panel = new JPanel(); //Create panel object
        panel.setLayout(new GridLayout(5, 1)); //Create grid layout for fields

        panel.add(itemNumberField); //Add itemNumberField to grid layout
        panel.add(bandNameField); //Add bandNameField to grid layout
        panel.add(albumNameField); //Add albumNameField to grid layout
        panel.add(stockUnitsField); //Add stockUnitsField to grid layout
        panel.add(priceField); //Add priceField to grid layout
        panel.add(totalValueField); //Add totalValueField to grid layout

        return panel;
    } //End createTextPanel method

    //Nested Button Listener Class
    class ButtonListener implements ActionListener { //Begin ButtonListener Class

        public void actionPerformed(ActionEvent e) { //Begin actionPerformed Method

            //Add button functions
            if (e.getActionCommand() == "Next") //If First button
                if (ArrayIndex < cds.length) //Test to not exceed upper bound of array
                    //get itemNumber and assign to text field
                    //get bandName and assign to text field
                    //get albumName and assign to text field
                    //get stockUnits and assign to text field
                    //get pricePerItem and set to text field
                    //get totalInventoryValue and assign to text field

                }//End if
        } //End actionPerformed Method
    } //End ButtonListener Class
} //End InventoryFrame Class

 * Program: Inventory Program Part 4
 * File: RockBand.java
 * Summary: This file holds the subclass RockBand of the superclass CD. This
 *          subclass includes a new variable, bandName, and the set/get methods
 *          associated with it.
 * Author: Joshua Lewis
 * Date: September 10, 2010

package inventoryprogrampart4;

public class RockBand extends CD
{ //Begin RockBand Class

    private String bandName; //Variable to hold name of band
    private final double RESTOCK_RATE = .05; //Percent of price for restock fee

    public void setBandName(String inName) //Access to set bandName variable
    { //Begin setBandName Method
        bandName = inName;
    } //End setBandName Method

    public String getBandName() //Access to bandName variable
    { //Begin getBandName Method
        return bandName;
    } //End getBandName Method

} //End RockBand Class

 * Program: Inventory Program Part 4
 * File: Comparator.java
 *  * Summary: This file is used to sort the array of CD objects used in the Inventory
 *             Program Part 4.
 * Author: Joshua Lewis
 * Date: September 10, 2010

package inventoryprogrampart4;
import java.util.Comparator;

public class AlbumNameComparator implements Comparator { //Begin AlbumNameComparator Class

    //Begin Compare Method
    public int compare(Object cdOne, Object cdTwo){ //Create two cd Objects to compare title

        //Use getProductName Method from CD class
        String title1 = ((RockBand)cdOne).getAlbumName().toUpperCase();
        //Use getProductName Method from CD class
        String title2 = ((RockBand)cdTwo).getAlbumName().toUpperCase();

        //Compare title of CD object 1 with title of CD object 2
        if (!(title1.equals(title2)))
            return title1.compareTo(title2);
            return title2.compareTo(title1);

    } //End compare Method

} //End AlbumNameComparator Class

 * Program: Inventory Program Part 4
 * File: Product.java
 * Summary: This contains the product class that holds the variables and methods
 *          associated with setting/getting information of product name, product
 *          number, cost, number in stock, and total value of stock for
 *          objects of class CD used in the Inventory Program Part 4.
 * Author: Joshua Lewis
 * Date: September 10, 2010

package inventoryprogrampart4;
import javax.swing.JOptionPane; //Import to use JOptionPane Class

public class CD { //Begin CD Class

    protected String itemNumber; //Variable to hold item number
    protected String albumName; //Variable to hold name of album
    protected int stockUnits; //Variable to hold number of units of item in stock
    protected double pricePerItem; //Variable to hold price per unit of the item
    protected double totalInventoryValue; //Variable to hold the total value of all units of item
    protected static double SumInventoryValue; //Variable to hold total value of all stock

    public CD() {}; //Empty constructor

    public CD(String inItemNumber, String inAlbumName, int inStock, double inPrice)
    { //Constructor to take itemNumber, albumName, stockUnits, and pricePerItem
        itemNumber = inItemNumber;
        albumName = inAlbumName;
        stockUnits = inStock;
        pricePerItem = inPrice;
    } //End Constructor

     //Accesses itemNumber to set variable
    public void setItemNumber(String inItemNumber){ //Begin setItemNumber Method
        itemNumber = inItemNumber;
    } //End setItemNumber Method

    //Access to variable itemNumber
    public String getItemNumber(){ //Begin getItemNumber Method
        return itemNumber;
    } //End getItemNumber Method

    //Accesses productName to set variable
    public void setAlbumName(String inAlbumName){ //Begin setAlbumName Method
       albumName = inAlbumName;
    } //End setAlbumName Method

    //Access to variable albumName
    public String getAlbumName(){ //Begin getAlbumName Method
        return albumName;
    } //End getAlbumName Method

    //Access numberOfUnitsInStock to set variable
    public void setUnits(int inStock){ //Begin setUnits Method
        stockUnits = inStock;
    } //End setUnits Method

    //Access to variable numberOfUnitsInStock
    public int getUnits(){ //Begin getUnits Method
        return stockUnits;
    } //End getUnits Method

    //Access pricePerItem to set variable
    public void setPrice(double inItemPrice){ //Begin setPrice Method
        this.pricePerItem  = inItemPrice;
    } //End setPrice Method

    //Access to pricePerItem variable
    public double getPrice(){ //Begin getPrice Method
        return pricePerItem;
    } //End getPrice Method

    public double calcInventoryValue() //Calculates total value of all units of item
    { //Begin calcInventoryValue Method
        totalInventoryValue  = pricePerItem * stockUnits;
        return totalInventoryValue;
    } //End calcInventoryValue Method

} //End CD Class

 * Program: InventoryDisplay Program Part 4
 * File: InventoryDisplay.java
 * Summary: This program establishes an inventory of five items
 *          of the RockBand class, which is a sub class of CD. These items are
 *          stored in an array and sorted. This program then displays all five
 *          items with their respective product name, product number, number
 *          in stock, cost, and total cost of all in stock in alphabetical order.
 *          The entire program uses a GUI for interaction.
 * Author: Joshua Lewis
 * Date: September 10, 2010

package inventoryprogrampart4;
import javax.swing.JFrame; //Import to use JFrame

public class InventoryDisplay { //Begin InventoryDisplay Class

    public static void main(String[] args) { //Begin Main Method

        JFrame frame = new InventoryFrame(); //Create InventoryFrame object

        frame.setSize(400, 200); //Set size of window. 400 is width, 200 is height
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Close application
        frame.setTitle("Inventory Program Part 4"); //Set title of window
        frame.setLocationRelativeTo(null); //Center the form
        frame.setVisible(true); //Display form

    } //End main Method

} //End InventoryDisplay Class

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Replies To: Displaying Variables to Gui

#2 krizjaz  Icon User is offline

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Re: Displaying Variables to Gui

Posted 11 September 2010 - 02:29 AM

Ok, here is your problem:
A constructor is used to create an instance of a class. It is really different from methods. Methods have return types. A constructor has none.
public void add(int index, String name){}

Here, void is the return type, in which it doesn't return something.
A constructor is just like this:
public MyFrame(){}

Let's go back to your code. In your InventoryFrame class, you have mistakenly put void in your constructor:
public void InventoryFrame() { //Begin Constructor

which, it should be:
public InventoryFrame() { //Begin Constructor

The objects should show up now. :)
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#3 n8wxs  Icon User is offline

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Re: Displaying Variables to Gui

Posted 11 September 2010 - 03:00 AM

krizjaz: good catch!
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#4 davidobryen  Icon User is offline

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Re: Displaying Variables to Gui

Posted 11 September 2010 - 08:04 AM

Could be an idea to try an IDE such as Eclipse:

The Eclipse warning in this case for
public void InventoryFrame() { //Begin Constructor


"This method has a constructor name"

This post has been edited by davidobryen: 11 September 2010 - 08:06 AM

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#5 joshklewis  Icon User is offline

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Re: Displaying Variables to Gui

Posted 11 September 2010 - 03:47 PM

Thankyou so much. I could not figure out what I was doing wrong. I just kept looking at it thinking that it should work and I could not figure out a reason why it did not work. I just got rid of the void in the constructor and it works perfectly now.
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