PriceTypeの区分にPriceインターフェースを設定

src/main/java/video/domain/Movie.java

@@ -23,7 +23,7 @@ public String getTitle() {
         return title;
     }
 
-    public int movieAmount(int daysRented) {
+    public int amount(int daysRented) {
         return priceType.amount(daysRented);
     }
 

src/main/java/video/domain/PriceType.java

@@ -2,27 +2,21 @@
 
 import video.domain.price.ChildrenPrice;
 import video.domain.price.NewReleasePrice;
+import video.domain.price.Price;
 import video.domain.price.RegularPrice;
 
 public enum PriceType {
-    CHILDREN,
-    REGULAR,
-    NEW_RELEASE;
+    CHILDREN(new ChildrenPrice()),
+    REGULAR(new RegularPrice()),
+    NEW_RELEASE(new NewReleasePrice());
 
-    private final RegularPrice regularPrice = new RegularPrice();
-    private final NewReleasePrice newReleasePrice = new NewReleasePrice();
-    private final ChildrenPrice childrenPrice = new ChildrenPrice();
+    Price price;
+
+    PriceType(Price price) {
+        this.price = price;
+    }
 
     int amount(int daysRented) {
-        switch (this) {
-            case REGULAR:
-                return regularPrice.amount(daysRented);
-            case NEW_RELEASE:
-                return newReleasePrice.amount(daysRented);
-            case CHILDREN:
-                return childrenPrice.amount(daysRented);
-            default:
-                throw new RuntimeException("ビデオの区分が誤っています");
-        }
+        return price.amount(daysRented);
     }
 }

src/main/java/video/domain/rental/Rental.java

@@ -24,7 +24,7 @@ public Movie getMovie() {
     public int amount() {
         // 金額を計算
         int daysRented = getDaysRented();
-        return movie.movieAmount(daysRented);
+        return movie.amount(daysRented);
     }
 
     public int frequentRenterPoints() {