diff --git a/BookFactory.java b/BookFactory.java
index 16a9cdb..56a9c1d 100644
--- a/BookFactory.java
+++ b/BookFactory.java
@@ -1,6 +1,6 @@
 /*
  *  Written by : Bin Hong Lee
- *  Last edited : 5/31/2016
+ *  Last edited : 6/8/2016
  */
 
 import java.util.*;
@@ -51,4 +51,17 @@ class BookFactory
 
     throw new NullPointerException();
   }
+
+  public void update(Book newBook)
+  {
+    for (int i = 0; i < books.size(); i++)
+    {
+      Book temp = books.get(i);
+
+      if(temp.getId() == newBook.getId())
+      {
+        books.set(i, newBook);
+      }
+    }
+  }
 }
diff --git a/UserFactory.java b/UserFactory.java
index 6ef5ab3..ffe569d 100644
--- a/UserFactory.java
+++ b/UserFactory.java
@@ -1,6 +1,6 @@
 /*
  *  Written by : Bin Hong Lee
- *  Last edited : 6/6/2016
+ *  Last edited : 6/7/2016
  */
 
 import java.util.*;