Use map for string and handler class

Java/pom.xml

@@ -40,6 +40,20 @@
                 <artifactId>maven-surefire-plugin</artifactId>
                 <version>${maven.maven-surefire-plugin.version}</version>
             </plugin>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-compiler-plugin</artifactId>
+            <configuration>
+              <source>9</source>
+              <target>9</target>
+            </configuration>
+          </plugin>
+          <plugin>
+            <groupId>com.hubspot.maven.plugins</groupId>
+            <artifactId>prettier-maven-plugin</artifactId>
+            <!-- Find the latest version at https://github.com/jhipster/prettier-java/releases -->
+            <version>0.8</version>
+          </plugin>
         </plugins>
     </build>
 

Java/src/main/java/com/gildedrose/AgedBrieItem.java

@@ -1,10 +0,0 @@
-package com.gildedrose;
-
-public class AgedBrieItem {
-  public static void handleDay(Item item) {
-    if (item.quality != 50) {
-      item.quality += 1;
-    }
-    item.sellIn -= 1;
-  }
-}

Java/src/main/java/com/gildedrose/AgedBrieItemHandler.java

@@ -0,0 +1,14 @@
+package com.gildedrose;
+
+public class AgedBrieItemHandler extends ItemHandler {
+
+  public AgedBrieItemHandler() {}
+
+  @Override
+  public void handleDay(Item item) {
+    if (item.quality != 50) {
+      item.quality += 1;
+    }
+    item.sellIn -= 1;
+  }
+}

Java/src/main/java/com/gildedrose/BackstagePassesItem.java

@@ -1,18 +0,0 @@
-package com.gildedrose;
-
-public class BackstagePassesItem {
-  public static void handleDay(Item item) {
-      // todo: make it so these items can't be initialized with over 50
-      if (item.quality == 50) {
-        return;
-      }
-      if (item.sellIn == 0) {
-        item.quality = 0;
-      } else if (item.sellIn <= 5) {
-        item.quality += 3;
-      } else if (item.sellIn <= 10) {
-        item.quality += 2;
-      }
-      item.sellIn -= 1;
-    }
-}

Java/src/main/java/com/gildedrose/BackstagePassesItemHandler.java

@@ -0,0 +1,20 @@
+package com.gildedrose;
+
+public class BackstagePassesItemHandler extends ItemHandler {
+
+  @Override
+  public void handleDay(Item item) {
+    // todo: make it so these items can't be initialized with over 50
+    if (item.quality == 50) {
+      return;
+    }
+    if (item.sellIn == 0) {
+      item.quality = 0;
+    } else if (item.sellIn <= 5) {
+      item.quality += 3;
+    } else if (item.sellIn <= 10) {
+      item.quality += 2;
+    }
+    item.sellIn -= 1;
+  }
+}

Java/src/main/java/com/gildedrose/GenericItemHandler.java

@@ -1,7 +1,9 @@
 package com.gildedrose;
 
-public class GenericItem {
-  public static void handleDay(Item item) {
+public class GenericItemHandler extends ItemHandler {
+
+  @Override
+  public void handleDay(Item item) {
     item.sellIn -= 1;
     if (item.quality == 0) {
       return;

Java/src/main/java/com/gildedrose/GildedRose.java

@@ -1,35 +1,45 @@
 package com.gildedrose;
 
+import java.lang.reflect.InvocationTargetException;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
 
 class GildedRose {
   public static final String AGED_BRIE = "Aged Brie";
   public static final String SULFURAS = "Sulfuras, Hand of Ragnaros";
-  public static final String BACKSTAGE_PASSES = "Backstage passes to a TAFKAL80ETC concert";
-
-  final List<Item> items;
+  public static final String BACKSTAGE_PASSES =
+    "Backstage passes to a TAFKAL80ETC concert";
+  private static Map<String, Class<? extends ItemHandler>> itemHandlerMap = Map.of(
+    AGED_BRIE,
+    AgedBrieItemHandler.class,
+    SULFURAS,
+    SulfurasItemHandler.class,
+    BACKSTAGE_PASSES,
+    BackstagePassesItemHandler.class
+  );
+  // make package-private
+  public final List<Item> items;
 
   public GildedRose(Item[] items) {
     this.items = Arrays.asList(items);
   }
 
+  // todo: refactor this to use Guice
+  private static void handleDay(Item item) {
+    // todo: refactor to use enum
+    try {
+      ItemHandler itemHandler = itemHandlerMap
+        .getOrDefault(item.name, GenericItemHandler.class)
+        .getDeclaredConstructor()
+        .newInstance();
+      itemHandler.handleDay(item);
+    } catch (InstantiationException | IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
   public void updateQuality() {
     items.forEach(GildedRose::handleDay);
   }
-
-  private static void handleDay(Item item) {
-    switch (item.name) {
-      case AGED_BRIE:
-        AgedBrieItem.handleDay(item);
-        return;
-      case SULFURAS:
-        return;
-      case BACKSTAGE_PASSES:
-        BackstagePassesItem.handleDay(item);
-        return;
-      default:
-        GenericItem.handleDay(item);
-    }
-  }
 }

Java/src/main/java/com/gildedrose/Item.java

@@ -1,21 +1,20 @@
 package com.gildedrose;
 
 public class Item {
+  public String name;
 
-    public String name;
+  public int sellIn;
 
-    public int sellIn;
+  public int quality;
 
-    public int quality;
+  public Item(String name, int sellIn, int quality) {
+    this.name = name;
+    this.sellIn = sellIn;
+    this.quality = quality;
+  }
 
-    public Item(String name, int sellIn, int quality) {
-        this.name = name;
-        this.sellIn = sellIn;
-        this.quality = quality;
-    }
-
-   @Override
-   public String toString() {
-        return this.name + ", " + this.sellIn + ", " + this.quality;
-    }
+  @Override
+  public String toString() {
+    return this.name + ", " + this.sellIn + ", " + this.quality;
+  }
 }

Java/src/main/java/com/gildedrose/ItemHandler.java

@@ -0,0 +1,6 @@
+package com.gildedrose;
+
+public abstract class ItemHandler {
+
+  public void handleDay(Item item) {}
+}

Java/src/main/java/com/gildedrose/ItemType.java

@@ -0,0 +1,3 @@
+package com.gildedrose;
+
+public enum ItemType {}

Java/src/main/java/com/gildedrose/SulfurasItem.java

@@ -1,4 +0,0 @@
-package com.gildedrose;
-
-public class SulfurasItem {
-}

Java/src/main/java/com/gildedrose/SulfurasItemHandler.java

@@ -0,0 +1,3 @@
+package com.gildedrose;
+
+public class SulfurasItemHandler extends ItemHandler {}

Java/src/test/java/com/gildedrose/GildedRoseTest.java

@@ -1,15 +1,15 @@
 package com.gildedrose;
 
-import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import org.junit.jupiter.api.Test;
+
 class GildedRoseTest {
   private static final int SULFURAS_QUALITY = 80;
 
   @Test
   public void agedBrieIncreasesInQualityByOneEachDay() {
-    Item[] items = new Item[]{new Item(GildedRose.AGED_BRIE, 2, 0)};
+    Item[] items = new Item[] { new Item(GildedRose.AGED_BRIE, 2, 0) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).quality, 1);
@@ -20,7 +20,9 @@ class GildedRoseTest {
   @Test
   public void sulfurasSellInDateNeverChanges() {
     int sellIn = 10;
-    Item[] items = new Item[]{new Item(GildedRose.SULFURAS, sellIn, SULFURAS_QUALITY)};
+    Item[] items = new Item[] {
+      new Item(GildedRose.SULFURAS, sellIn, SULFURAS_QUALITY)
+    };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).sellIn, sellIn);
@@ -30,7 +32,9 @@ class GildedRoseTest {
 
   @Test
   public void sulfurasValueNeverChanges() {
-    Item[] items = new Item[]{new Item(GildedRose.SULFURAS, 10, SULFURAS_QUALITY)};
+    Item[] items = new Item[] {
+      new Item(GildedRose.SULFURAS, 10, SULFURAS_QUALITY)
+    };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).quality, SULFURAS_QUALITY);
@@ -40,7 +44,9 @@ class GildedRoseTest {
 
   @Test
   public void sulfurasValueIsAlways80() {
-    Item[] items = new Item[]{new Item(GildedRose.SULFURAS, 10, SULFURAS_QUALITY)};
+    Item[] items = new Item[] {
+      new Item(GildedRose.SULFURAS, 10, SULFURAS_QUALITY)
+    };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).quality, SULFURAS_QUALITY);
@@ -49,7 +55,9 @@ class GildedRoseTest {
   @Test
   public void backstagePassesQualityIncreasesByTwoWhenThereAreTenDaysOrLessBeforeTheConcert() {
     int quality = 0;
-    Item[] items = new Item[]{new Item(GildedRose.BACKSTAGE_PASSES, 10, quality)};
+    Item[] items = new Item[] {
+      new Item(GildedRose.BACKSTAGE_PASSES, 10, quality)
+    };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).quality, 2);
@@ -60,7 +68,9 @@ class GildedRoseTest {
   @Test
   public void backstagePassesQualityIncreasesByThreeWhenThereAreFiveDaysOrLessBeforeTheConcert() {
     int quality = 0;
-    Item[] items = new Item[]{new Item(GildedRose.BACKSTAGE_PASSES, 5, quality)};
+    Item[] items = new Item[] {
+      new Item(GildedRose.BACKSTAGE_PASSES, 5, quality)
+    };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).quality, 3);
@@ -73,7 +83,9 @@ class GildedRoseTest {
   @Test
   public void backstagePassesQualityDropsToZeroAfterTheConcert() {
     int quality = 10;
-    Item[] items = new Item[]{new Item(GildedRose.BACKSTAGE_PASSES, 1, quality)};
+    Item[] items = new Item[] {
+      new Item(GildedRose.BACKSTAGE_PASSES, 1, quality)
+    };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).quality, 13);
@@ -85,7 +97,7 @@ class GildedRoseTest {
   public void qualityIsNeverNegativeForGenericItems() {
     // todo: should add a similar case for conjured
     int quality = 1;
-    Item[] items = new Item[]{new Item("generic item", 5, quality)};
+    Item[] items = new Item[] { new Item("generic item", 5, quality) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).quality, 0);
@@ -97,7 +109,7 @@ class GildedRoseTest {
 
   @Test
   public void qualityIsNeverOverFiftyForAgedBrie() {
-    Item[] items = new Item[]{new Item(GildedRose.AGED_BRIE, 5, 50)};
+    Item[] items = new Item[] { new Item(GildedRose.AGED_BRIE, 5, 50) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).quality, 50);
@@ -109,7 +121,7 @@ class GildedRoseTest {
 
   @Test
   public void qualityIsNeverOverFiftyForBackstagePasses() {
-    Item[] items = new Item[]{new Item(GildedRose.BACKSTAGE_PASSES, 5, 50)};
+    Item[] items = new Item[] { new Item(GildedRose.BACKSTAGE_PASSES, 5, 50) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).quality, 50);
@@ -121,7 +133,7 @@ class GildedRoseTest {
 
   @Test
   public void qualityDecreasesByOneEachDayForGenericItems() {
-    Item[] items = new Item[]{new Item("generic item", 5, 5)};
+    Item[] items = new Item[] { new Item("generic item", 5, 5) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).quality, 4);
@@ -133,7 +145,7 @@ class GildedRoseTest {
 
   @Test
   public void qualityDecreasesByTwoEachDayForGenericItemsAfterSellInDate() {
-    Item[] items = new Item[]{new Item("generic item", 1, 6)};
+    Item[] items = new Item[] { new Item("generic item", 1, 6) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).quality, 5);
@@ -145,7 +157,7 @@ class GildedRoseTest {
 
   @Test
   public void sellInDateDecreasesByOneEachDayForAgedBrie() {
-    Item[] items = new Item[]{new Item(GildedRose.AGED_BRIE, 5, 1)};
+    Item[] items = new Item[] { new Item(GildedRose.AGED_BRIE, 5, 1) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).sellIn, 4);
@@ -157,7 +169,7 @@ class GildedRoseTest {
 
   @Test
   public void sellInDateDecreasesByOneEachDayForBackstagePasses() {
-    Item[] items = new Item[]{new Item(GildedRose.BACKSTAGE_PASSES, 5, 1)};
+    Item[] items = new Item[] { new Item(GildedRose.BACKSTAGE_PASSES, 5, 1) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).sellIn, 4);
@@ -169,7 +181,7 @@ class GildedRoseTest {
 
   @Test
   public void sellInDateDecreasesByOneEachDayForGenericItems() {
-    Item[] items = new Item[]{new Item("generic item", 5, 1)};
+    Item[] items = new Item[] { new Item("generic item", 5, 1) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).sellIn, 4);
@@ -181,7 +193,7 @@ class GildedRoseTest {
 
   @Test
   public void sellInDateCanBeNegativeForGenericItems() {
-    Item[] items = new Item[]{new Item("generic item", 1, 1)};
+    Item[] items = new Item[] { new Item("generic item", 1, 1) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).sellIn, 0);
@@ -193,7 +205,7 @@ class GildedRoseTest {
 
   @Test
   public void sellInDateCanBeNegativeForAgedBrie() {
-    Item[] items = new Item[]{new Item(GildedRose.AGED_BRIE, 1, 1)};
+    Item[] items = new Item[] { new Item(GildedRose.AGED_BRIE, 1, 1) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).sellIn, 0);
@@ -205,7 +217,7 @@ class GildedRoseTest {
 
   @Test
   public void sellInDateCanBeNegativeForBackStagePasses() {
-    Item[] items = new Item[]{new Item(GildedRose.BACKSTAGE_PASSES, 1, 1)};
+    Item[] items = new Item[] { new Item(GildedRose.BACKSTAGE_PASSES, 1, 1) };
     GildedRose app = new GildedRose(items);
     app.updateQuality();
     assertEquals(app.items.get(0).sellIn, 0);
@@ -217,7 +229,7 @@ class GildedRoseTest {
 
   @Test
   public void itUpdatesAllItemsPassedIn() {
-    Item[] items = new Item[]{
+    Item[] items = new Item[] {
       new Item("generic item 1", 5, 5),
       new Item("generic item 2", 5, 10)
     };

Java/src/test/java/com/gildedrose/TexttestFixture.java

@@ -1,35 +1,36 @@
 package com.gildedrose;
 
 public class TexttestFixture {
-    public static void main(String[] args) {
-        Item[] items = new Item[] {
-                new Item("+5 Dexterity Vest", 10, 20), //
-                new Item("Aged Brie", 2, 0), //
-                new Item("Elixir of the Mongoose", 5, 7), //
-                new Item("Sulfuras, Hand of Ragnaros", 0, 80), //
-                new Item("Sulfuras, Hand of Ragnaros", -1, 80),
-                new Item("Backstage passes to a TAFKAL80ETC concert", 15, 20),
-                new Item("Backstage passes to a TAFKAL80ETC concert", 10, 49),
-                new Item("Backstage passes to a TAFKAL80ETC concert", 5, 49),
-                // this conjured item does not work properly yet
-                new Item("Conjured Mana Cake", 3, 6) };
 
-        GildedRose app = new GildedRose(items);
+  public static void main(String[] args) {
+    Item[] items = new Item[] {
+      new Item("+5 Dexterity Vest", 10, 20), //
+      new Item("Aged Brie", 2, 0), //
+      new Item("Elixir of the Mongoose", 5, 7), //
+      new Item("Sulfuras, Hand of Ragnaros", 0, 80), //
+      new Item("Sulfuras, Hand of Ragnaros", -1, 80),
+      new Item("Backstage passes to a TAFKAL80ETC concert", 15, 20),
+      new Item("Backstage passes to a TAFKAL80ETC concert", 10, 49),
+      new Item("Backstage passes to a TAFKAL80ETC concert", 5, 49),
+      // this conjured item does not work properly yet
+      new Item("Conjured Mana Cake", 3, 6)
+    };
 
-        int days = 2;
-        if (args.length > 0) {
-            days = Integer.parseInt(args[0]) + 1;
-        }
+    GildedRose app = new GildedRose(items);
 
-        for (int i = 0; i < days; i++) {
-            System.out.println("-------- day " + i + " --------");
-            System.out.println("name, sellIn, quality");
-            for (Item item : items) {
-                System.out.println(item);
-            }
-            System.out.println();
-            app.updateQuality();
-        }
+    int days = 2;
+    if (args.length > 0) {
+      days = Integer.parseInt(args[0]) + 1;
     }
 
+    for (int i = 0; i < days; i++) {
+      System.out.println("-------- day " + i + " --------");
+      System.out.println("name, sellIn, quality");
+      for (Item item : items) {
+        System.out.println(item);
+      }
+      System.out.println();
+      app.updateQuality();
+    }
+  }
 }