Created 3 files:

- TransactionCalculatorFactory
- PurchaseCalculatorFactory
- SaleCalculatorFactory

src/main/java/millions/calculators/PurchaseCalculatorFactory.java

@@ -0,0 +1,18 @@
+package millions.calculators;
+
+import millions.Share;
+
+public class PurchaseCalculatorFactory extends TransactionCalculatorFactory {
+  Share share;
+
+  @Override
+  public void setShare(Share share) {
+    this.share = share;
+  }
+
+  @Override
+  public TransactionCalculator createCalculator() {
+    return new PurchaseCalculator(share);
+  }
+
+}

src/main/java/millions/calculators/SaleCalculatorFactory.java

@@ -0,0 +1,16 @@
+package millions.calculators;
+
+import millions.Share;
+
+public class SaleCalculatorFactory extends TransactionCalculatorFactory {
+  Share share;
+
+  @Override
+  public void setShare(Share share) {
+    this.share = share;
+  }
+  @Override
+  public TransactionCalculator createCalculator() {
+    return new SaleCalculator(share);
+  }
+}

src/main/java/millions/calculators/TransactionCalculatorFactory.java

@@ -0,0 +1,8 @@
+package millions.calculators;
+
+import millions.Share;
+
+public abstract class TransactionCalculatorFactory {
+  public abstract void setShare(Share share);
+  public abstract TransactionCalculator createCalculator();
+}