Added Checkstyle to PurchaseCalculator

src/main/java/Model/PurchaseCalculator.java

@@ -1,30 +1,38 @@
 package Model;
+
 import java.math.BigDecimal;
 
+/**
+ * PurchaseCalculator class that does calculations.
+ */
 public class PurchaseCalculator implements TransactionCalculator {
-    private BigDecimal purchasePrice;
-    private BigDecimal quantity;
+  private final BigDecimal purchasePrice;
+  private final BigDecimal quantity;
 
-    public PurchaseCalculator(Share share) {
-        this.purchasePrice = share.getPurchasePrice();
-        this.quantity = share.getQuantity();
-    }
+  public PurchaseCalculator(Share share) {
+    this.purchasePrice = share.getPurchasePrice();
+    this.quantity = share.getQuantity();
+  }
 
-    public BigDecimal calculateGross() {
-        return this.purchasePrice.multiply(this.quantity);
-    }
+  @Override
+  public BigDecimal calculateGross() {
+    return this.purchasePrice.multiply(this.quantity);
+  }
 
-    public BigDecimal calculateCommission() {
-        BigDecimal rate = new BigDecimal("0.005");
-        return calculateGross().multiply(rate);
-    }
+  @Override
+  public BigDecimal calculateCommission() {
+    BigDecimal rate = new BigDecimal("0.005");
+    return calculateGross().multiply(rate);
+  }
 
-    public BigDecimal calculateTax() {
-        BigDecimal tax = new BigDecimal("0");
-        return tax;
-    }
+  @Override
+  public BigDecimal calculateTax() {
+    BigDecimal tax = new BigDecimal("0");
+    return tax;
+  }
 
-    public BigDecimal calculateTotal() {
-        return calculateGross().add(calculateCommission()).add(calculateTax());
-    }
+  @Override
+  public BigDecimal calculateTotal() {
+    return calculateGross().add(calculateCommission()).add(calculateTax());
+  }
 }