update,

it114105/itp3914/Lab12/Ex1/Ex1.java

@@ -0,0 +1,17 @@
+public class Ex1 {
+    public static void main(String [] args) {
+		Invoice inv = new Invoice("A123", 4);
+		double total=0;
+ 
+		inv.addItem("U-231", 34.5, 10);
+		inv.addItem("J-994", 124.5, 5);
+		inv.addItem("K-674", 4.5, 100);
+ 
+		for (int i=0; i<inv.getItemCount(); i++) {
+			System.out.println(inv.getItem(i));
+			total += inv.getItem(i).getItemTotal();
+		}
+		System.out.println("Invoice Total = " + total);
+	}
+
+}

it114105/itp3914/Lab12/Ex1/Invoice.java

@@ -0,0 +1,42 @@
+public class Invoice {
+	private String invNumber;
+	private Item [] itemList;
+	private int itemCount;
+	
+	public Invoice(String invNumber, int itemNum) {
+		// 1. Set instance variable invNumber
+		// 2. Create an array of Item with number of elements specified 
+		//    by parameter itemNum. Refer to Topic 4.6, Slide 9
+		// 3. Set itemCount to 0, as there is no Item initially.
+		this.invNumber = invNumber;
+        itemList = new Item[itemNum];
+        itemCount = 0;
+	}
+ 
+	public String getInvNumber() {
+		return invNumber;
+	}
+ 
+	public Item[] getItemList() {
+		return itemList;
+	}
+	
+	public int getItemCount() {
+		return itemCount;
+	}
+ 
+	public Item getItem(int index) {
+		return itemList[index];
+	}
+ 
+	public void addItem(String productCode, double price, int quantity) {
+		if (itemCount < itemList.length) {
+			// create a new Item; Refer to Topic 4.6, Slide 9
+			// save item to appropriate element in itemList
+			itemList[itemCount] = new Item(productCode, price, quantity);
+			itemCount++;
+		} else {
+			System.out.println("Failed to add new item; max already");
+		}
+	}
+}

it114105/itp3914/Lab12/Ex1/Item.java

@@ -0,0 +1,19 @@
+public class Item {
+	private String productCode;
+	private double price;
+	private int quantity;
+ 
+	public Item(String productCode, double price, int quantity) {
+        this.productCode = productCode;
+        this.price = price;
+        this.quantity = quantity;
+	}
+ 
+	public double getItemTotal() {
+		return price * quantity;
+	}
+ 
+	public String toString() {
+		return productCode +":" + price + "*" + quantity + "=" + getItemTotal();
+	}
+}