Create TransactionFactory class

src/main/java/Model/TransactionFactory.java

@@ -0,0 +1,22 @@
+package Model;
+
+/**
+ * Factory for creating transaction objects
+ */
+public class TransactionFactory {
+
+    /**
+     * Create purchase transaction
+     */
+    public static Transaction createPurchase(Share share, int week) {
+        return new Purchase(share, week);
+    }
+
+    /**
+     * Create sale transaction
+     */
+    public static Transaction createSale(Share share, int week) {
+        return new Sale(share, week);
+    }
+
+}