Add Class inheritance and refactoring of the code

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

@@ -1,32 +1,16 @@
 package com.gildedrose;
 
-public class AgedBrie {
-    private Item item;
+public class AgedBrie extends RegularItem {
 
     public AgedBrie(Item item) {
         this.item=item;
     }
 
     public void updateQuaility() {
-        increaseQuality();
         if (itemHasExpired()) {
-            increaseQuality();
-        }
-    }
-
-    private void increaseQuality() {
-        if (item.quality < 50) {
-            item.quality += 1;
-        }
-    }
-
-    private boolean itemHasExpired() {
-        boolean condition;
-        if (item.sellIn < 0) {
-            condition = true;
+            increaseQualityBy(2);
         } else {
-            condition = false;
+            increaseQualityBy(1);
         }
-        return condition;
     }
 }

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

@@ -1,38 +1,20 @@
 package com.gildedrose;
 
-public class BackStageItem {
-    private Item item;
-
+public class BackStageItem extends RegularItem{
     public BackStageItem(Item item) {
         this.item=item;
     }
 
     public void update() {
-        increaseQuality();
+        increaseQualityBy(1);
         if (item.sellIn < 10) {
-            increaseQuality();
+            increaseQualityBy(1);
         }
         if (item.sellIn < 5) {
-            increaseQuality();
+            increaseQualityBy(1);
         }
         if (itemHasExpired()) {
             item.quality -= item.quality;
         }
     }
-
-    private void increaseQuality() {
-        if (item.quality < 50) {
-            item.quality += 1;
-        }
-    }
-
-    private boolean itemHasExpired() {
-        boolean condition;
-        if (item.sellIn < 0) {
-            condition = true;
-        } else {
-            condition = false;
-        }
-        return condition;
-    }
 }

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

@@ -0,0 +1,14 @@
+package com.gildedrose;
+
+public class ConjuredItem extends RegularItem {
+    public ConjuredItem(Item item) {
+        this.item=item;
+    }
+
+    public void updateQuality() {
+        decreaseQualityBy(1);
+        if (itemHasExpired()) {
+            decreaseQualityBy(1);
+        }
+    }
+}

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

@@ -5,6 +5,7 @@ class GildedRoseItem {
     public static final String SULFURA = "Sulfuras, Hand of Ragnaros";
     public static final String AGED_BRIE = "Aged Brie";
     public static final String BACKSTAGE = "Backstage passes to a TAFKAL80ETC concert";
+    public static final String CONJURED = "Conjured Mana Cake";
 
 
     public GildedRoseItem(Item[] items) {
@@ -22,6 +23,9 @@ class GildedRoseItem {
         } else if (item.name.equals(BACKSTAGE)) {
             BackStageItem backStageItem = new BackStageItem(item);
             backStageItem.update();
+        } else if (item.name.equals(CONJURED)) {
+            ConjuredItem conjuredItem = new ConjuredItem(item);
+            conjuredItem.updateQuality();
         } else {
            RegularItem regularItem = new RegularItem(item);
            regularItem.updateQuality();

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

@@ -1,21 +1,25 @@
 package com.gildedrose;
 
 public class RegularItem {
-    private Item item;
+    public Item item;
+
+    public RegularItem() {
+
+    }
 
     public RegularItem(Item item) {
         this.item = item;
     }
 
     public void updateQuality() {
-        if (itemHasExpired(item)) {
-            decreaseQualityTwice();
+        if (itemHasExpired()) {
+            decreaseQualityBy(2);
         } else {
-            decreaseQuality();
+            decreaseQualityBy(1);
         }
     }
 
-    private boolean itemHasExpired(Item item) {
+    protected boolean itemHasExpired() {
         boolean condition;
         if (item.sellIn < 0) {
             condition = true;
@@ -25,16 +29,25 @@ public class RegularItem {
         return condition;
     }
 
-
-    private void decreaseQualityTwice() {
-        decreaseQuality();
-        decreaseQuality();
+    protected void increaseQualityBy(int factor) {
+        item.quality += factor;
+        qualityOfAnItemIsNotMoreThan(50);
     }
 
-    private void decreaseQuality() {
-        if (item.quality > 0) {
-            item.quality -= 1;
+    protected void decreaseQualityBy(int factor) {
+        item.quality -= factor;
+        qualityOfAnItemIsNeverNegative();
+    }
+
+    private void qualityOfAnItemIsNotMoreThan(int limit) {
+        if (item.quality > limit) {
+            item.quality = limit;
         }
     }
 
+    private void qualityOfAnItemIsNeverNegative() {
+        if (item.quality < 0) {
+            item.quality = 0;
+        }
+    }
 }