docs: update version number

version-number/README.md

@@ -21,7 +21,7 @@ Ensure data consistency and integrity by tracking changes to data with version n
 
 ## Explanation
 
-Real world example
+Real-world example
 
 > Consider a library system where multiple librarians can update the details of books simultaneously. Each book entry in the library's database has a version number. When a librarian wants to update a book's details, the system checks the version number of the entry. If the version number matches the current version in the database, the update proceeds, and the version number is incremented. If the version number has changed, it means another librarian has already updated the book details, prompting the system to notify the librarian of the conflict and suggesting a review of the latest changes. This ensures that updates do not overwrite each other unintentionally, maintaining data integrity and consistency.
 
@@ -43,10 +43,10 @@ We have a `Book` entity, which is versioned, and has a copy-constructor:
 @Getter
 @Setter
 public class Book {
+    
     private long id;
     private String title = "";
     private String author = "";
-
     private long version = 0; // version number
 
     public Book(Book book) {
@@ -62,6 +62,7 @@ We also have `BookRepository`, which implements concurrency control:
 
 ```java
 public class BookRepository {
+    
   private final Map<Long, Book> collection = new HashMap<>();
 
   public void update(Book book) throws BookNotFoundException, VersionMismatchException {
@@ -95,10 +96,25 @@ public class BookRepository {
 }
 ```
 
-Here's the concurrency control in action:
+Here's the version number pattern in action:
 
 ```java
+public class App {
+    
+    private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+
+    public static void main(String[] args) throws
+            BookDuplicateException,
+            BookNotFoundException,
+            VersionMismatchException {
         var bookId = 1;
+
+        var bookRepository = new BookRepository();
+        var book = new Book();
+        book.setId(bookId);
+        bookRepository.add(book); // adding a book with empty title and author
+        LOGGER.info("An empty book with version {} was added to repository", book.getVersion());
+
         // Alice and Bob took the book concurrently
         final var aliceBook = bookRepository.get(bookId);
         final var bobBook = bookRepository.get(bookId);
@@ -118,19 +134,18 @@ try {
             LOGGER.info("Exception: {}", e.getMessage());
             // Now Bob should reread actual book from repository, do his changes again and save again
         }
+    }
+}
 ```
 
 Program output:
 
-```java
-Alice updates the book with new version 1
-Bob tries to update the book with his version 0
-Exception: Tried to update stale version 0 while actual version is 1
 ```
-
+14:51:04.119 [main] INFO com.iluwatar.versionnumber.App -- An empty book with version 0 was added to repository
-## Class diagram
+14:51:04.122 [main] INFO com.iluwatar.versionnumber.App -- Alice updates the book with new version 1
-
+14:51:04.122 [main] INFO com.iluwatar.versionnumber.App -- Bob tries to update the book with his version 0
-![Version Number](./etc/version-number.urm.png "Version Number pattern class diagram")
+14:51:04.123 [main] INFO com.iluwatar.versionnumber.App -- Exception: Tried to update stale version 0 while actual version is 1
+```
 
 ## Applicability
 
@@ -140,9 +155,9 @@ Exception: Tried to update stale version 0 while actual version is 1
 
 ## Tutorials
 
-* [JPA entity versioning - byteslounge.com](https://www.byteslounge.com/tutorials/jpa-entity-versioning-version-and-optimistic-locking)
+* [JPA entity versioning (byteslounge.com)](https://www.byteslounge.com/tutorials/jpa-entity-versioning-version-and-optimistic-locking)
-* [Optimistic Locking in JPA - Baeldung](https://www.baeldung.com/jpa-optimistic-locking)
+* [Optimistic Locking in JPA (Baeldung)](https://www.baeldung.com/jpa-optimistic-locking)
-* [Versioning Entity - java2s.com](http://www.java2s.com/Tutorial/Java/0355__JPA/VersioningEntity.htm)
+* [Versioning Entity (java2s.com)](http://www.java2s.com/Tutorial/Java/0355__JPA/VersioningEntity.htm)
 
 ## Known Uses