refactored codes

src/main/java/com/zipcodewilmington/gildedrose/Inventory.java

@@ -2,7 +2,12 @@ package com.zipcodewilmington.gildedrose;
 
 
 public class Inventory {
+    private static final int MAX_QUALITY = 50;
+    private static final int MIN_QUALITY = 0;
     private Item[] items;
+    protected static final String AGED_BRIE = "Aged Brie";
+    protected static final String BACKSTAGE_PASS = "Backstage passes to a TAFKAL80ETC concert";
+    protected static final String SULFURAS = "Sulfuras, Hand of Ragnaros";
 
     public Inventory(Item[] items) {
         super();
@@ -12,55 +17,58 @@ public class Inventory {
 
     public void updateQuality() {
         for (int i = 0; i < items.length; i++) {
-            if (!items[i].getName().equals("Aged Brie")
-                    && !items[i].getName().equals("Backstage passes to a TAFKAL80ETC concert")) {
-                if (items[i].getQuality() > 0) {
-                    if (!items[i].getName().equals("Sulfuras, Hand of Ragnaros")) {
-                        items[i].setQuality(items[i].getQuality() - 1);
-                    }
-                }
-            } else {
-                if (items[i].getQuality() < 50) {
-                    items[i].setQuality(items[i].getQuality() + 1);
+            Item item = items[i];
+            String itemName = item.getName();
 
-                    if (items[i].getName() == "Backstage passes to a TAFKAL80ETC concert") {
-                        if (items[i].getSellIn() < 11) {
-                            if (items[i].getQuality() < 50) {
-                                items[i].setQuality(items[i].getQuality() + 1);
-                            }
-                        }
+            if (!SULFURAS.equals(itemName)) {
+                item.setSellIn(item.getSellIn() - 1);
+            }
 
-                        if (items[i].getSellIn() < 6) {
-                            if (items[i].getQuality() < 50) {
-                                items[i].setQuality(items[i].getQuality() + 1);
-                            }
-                        }
-                    }
-                }
+            if (AGED_BRIE.equals(itemName)) {
+                updateQuality(item, 1, 2);
+            } else if (BACKSTAGE_PASS.equals(itemName)){
+                updateBackstagePass(item, itemName);
+            } else if (SULFURAS.equals(itemName)){
+                // do nothing
+            } else {
+                updateQuality(item, -1, -2);
             }
+        }
+    }
 
-            if (!items[i].getName().equals("Sulfuras, Hand of Ragnaros")) {
-                items[i].setSellIn(items[i].getSellIn() - 1);
+    private void updateBackstagePass(Item item, String itemName) {
+        if (item.getSellIn() < 0) {
+            item.setQuality(0);
+        } else if (item.getQuality() < 50) {
+            item.setQuality(item.getQuality() + 1);
+            if (item.getSellIn() < 11) {
+                if (item.getQuality() < 50) {
+                    item.setQuality(item.getQuality() + 1);
+                }
             }
 
-            if (items[i].getSellIn() < 0) {
-                if (!items[i].getName().equals("Aged Brie")) {
-                    if (!items[i].getName().equals("Backstage passes to a TAFKAL80ETC concert")) {
-                        if (items[i].getQuality() > 0) {
-                            if (!items[i].getName().equals("Sulfuras, Hand of Ragnaros")) {
-                                items[i].setQuality(items[i].getQuality() - 1);
-                            }
-                        }
-                    } else {
-                        items[i].setQuality(items[i].getQuality()
-                                - items[i].getQuality());
-                    }
-                } else {
-                    if (items[i].getQuality() < 50) {
-                        items[i].setQuality(items[i].getQuality() + 1);
-                    }
+            if (item.getSellIn() < 6) {
+                if (item.getQuality() < 50) {
+                    item.setQuality(item.getQuality() + 1);
                 }
             }
         }
+
+    }
+
+    private void updateQuality(Item item, int quality, int passedSellInDateQuality) {
+        int itemQuality = item.getQuality();
+        if (item.getSellIn() < 0) {
+            item.setQuality(itemQuality + passedSellInDateQuality);
+        } else {
+            item.setQuality(itemQuality + quality);
+        }
+
+        if (item.getQuality() > MAX_QUALITY) {
+            item.setQuality(MAX_QUALITY);
+        } else if (item.getQuality() < MIN_QUALITY) {
+            item.setQuality(MIN_QUALITY);
+        }
+
     }
 }