Reusing a variable from a new object instance

Question

I'm developing a stock list array for an assignment I'm currently working on. I've got most of it done, and it seems to be working for the most part, but I'm having trouble getting an array to accept individual variable entries created by new object instances in TestQ3.java.
I think problem is because the variable itemCode in CraftItem.java is being overwritten by the creation of a new object instance in the TestQ3.java file. I've tested it and believe this to be true.
I can add a String of my own choosing by using testArray.addCraftItemToStock(itemCode); line but I want to get the program to reuse the itemCode values that have already been created by the four new object instances in TestQ3.java. For example, I want to be able to add more instances of them to the testArray.
As I'm still relatively new to Java programming, I'm wondering how to do this. I've tried several solutions but I'm not getting anywhere. I'd appreciate it if anyone has any ideas?
Here's my code:
TestQ3.java
public class TestQ3 {
  public static void main(String args[]) {
    // creating a new StockItem array
    CraftStock testArray = new CraftStock(CraftStock.initialStockCapacity);
    // creating new object instance for Glue
    Glue gluePVA = new Glue("PVA Glue",250,"789012",2.50);
    // adds gluePVA item code to the testArray list
    // testArray.addCraftItemToStock(gluePVA.getItemCode());
    // creating new object instance for Card
    Card colouredCard = new Card ("Coloured Card","A3","654321",1.25);
    // adds coloured card item code to the testArray list
    // testArray.addCraftItemToStock(colouredCard.getItemCode());
    // creating new object instance for Glue
    Glue superGlue = new Glue ("Super Glue",25,"210987",1.50);
    // adds superGlue item code to the testArray list
    // testArray.addCraftItemToStock(superGlue.getItemCode());
    // creating new object instance for Card
    Card whiteCard = new Card ("White Card","A4","123456",0.50);
    // adds superGlue item code to the testArray list
    // testArray.addCraftItemToStock(whiteCard.getItemCode());
    // display complete stocklist
    testArray.displayCraftStockList();
    // this adds the itemCode from gluePVA to the array but
    // it comes out as the last itemCode entry 123456 rather than 789012
    // when I run the code. The problem may lie with variable itemCode
    testArray.addCraftItemToStock(gluePVA.getItemCode());
    // display complete stocklist
    testArray.displayCraftStockList();
CraftItem.java
public class CraftItem {
  // instance variables
  public static String itemCode;
  private double price;
  //private int stockCount;
  // constructor
  public CraftItem(String itemCodeValue, double itemPriceValue){
    itemCode = itemCodeValue;
    price = itemPriceValue;
    //CraftStock.addCraftItemToStock(itemCode);
    //stockCount++;
  // getter for itemCode
  public String getItemCode() {
    return itemCode;
  // getter for price
  public double getPrice() {
    return price;
  // setter for itemCode
  public void setItemCode(String itemCodeValue) {
    itemCode = itemCodeValue;
  // setter for price
  public void setPrice(double itemPriceValue) {
    price = itemPriceValue;
  // toString() value
  public String toString() {
    return "Item code is " + itemCode + " and costs " + price + " pounds.";
Glue.java
public class Glue extends CraftItem{
  // Instance variables
  private String glueType;
  private double glueVolume;
  // Constructor
  public Glue(String glueType, double glueVolume,
   String itemCodeValue, double itemPriceValue) {
        super(itemCodeValue, itemPriceValue);
        glueType = glueType;
        glueVolume = glueVolume;
  // getter
  public String getGlueType() {
    return glueType;
  // getter
  public double getGlueVolume() {
    return glueVolume;
  // setter
  public void setGlueType(String glueTypeValue) {
    glueType = glueTypeValue;
  public void setGlueVolume(double glueVolumeValue) {
    glueVolume = glueVolumeValue;
  // toString
  public String toString() {
    return glueType + ", " + glueVolume + "ml, item code is "
     + super.getItemCode() + " and costs " + super.getPrice() + " pounds.";
Card.java
public class Card extends CraftItem{
  // instance variables
  private String cardType;
  private String cardSize;
  // Constructor
  // added super(itemCodeValue, itemPriceValue) to call on CraftItem
  public Card(String cardTypeValue, String cardSizeValue,
   String itemCodeValue, double itemPriceValue) {
        super(itemCodeValue, itemPriceValue);
        cardType = cardTypeValue;
        cardSize = cardSizeValue;
  // getter
  public String getCardType() {
    return cardType;
  // getter
  public String getCardSize() {
    return cardSize;
  // setter
  public void setCardType(String cardTypeValue) {
    cardType = cardTypeValue;
  // setter
  public void setCardSize(String cardSizeValue) {
    cardSize = cardSizeValue;
  // toString
  // using super. to call on methods from superclass CraftItem
  public String toString() {
    return cardType + ", size " + cardSize + ", item code is "
     + super.getItemCode() + " and costs " + super.getPrice() + " pounds.";
CraftStock.java
public class CraftStock {
    public static int currentStockLevel;
    public static String[] craftStock;
    public static int initialStockCapacity = 10;
    public CraftStock(int initialStockCapacity) {
        currentStockLevel = 0;
        craftStock = new String[initialStockCapacity];
    public int currentStockLevel() {
        return currentStockLevel;
    public static void addCraftItemToStock(String itemCodeValue) {
        if(currentStockLevel == 10){
          System.out.println("Stock list full: cannot add new item code." +
            "\nPlease remove an item if you want to add a new one.");
        else{
        craftStock[currentStockLevel] = itemCodeValue;
        currentStockLevel++;
        System.out.println("Item added");
    public void removeCraftItemFromStock(String itemCode){
      findStockItem(itemCode);
      int i = -1;
        do {
            i++;
        } while (!craftStock.equals(itemCode));
for (int j = i; j < currentStockLevel - 1; j++) {
craftStock[j] = craftStock[j + 1];
currentStockLevel--;
System.out.println("Item removed");
private int findStockItem(String itemCode){
int index = 0;
for(int i = 0; i < currentStockLevel; i++){
if(craftStock[i].equals(itemCode)){
index = i;
break;
else{
index = -1;
return index;
public void displayCraftStockList() {
if(currentStockLevel == 0){
System.out.println("There are no items in the stock list");
else{
for(int i = 0; i < currentStockLevel; i++){
System.out.println("Item at " + (i + 1) + " is " + craftStock[i]);
Message was edited by:
Nikarius

Answer 1

An instance variable relates to an object. If you require a variable to be available across multiple objects of the same class then I suggest you declare a class variable using the static keyword in your declaration.
HTH