Merge entity collections

Author: AnghelLeonard

HibernateSpringBootMergeCollections/src/main/java/com/bookstore/MainApplication.java

@@ -25,30 +25,33 @@ public static void main(String[] args) {
     public ApplicationRunner init() {
         return args -> {
 
-            System.out.println("------------------- Joana Nimar's Books --------------------");
-            List<Book> books = bookstoreService.fetchBooksOfAuthor("Joana Nimar");
+            System.out.println("\n------------------- Joana Nimar's Books --------------------");
+            List<Book> detachedBooks = bookstoreService.fetchBooksOfAuthor("Joana Nimar");
 
-            books.forEach(b -> System.out.println(b));
+            detachedBooks.forEach(b -> System.out.println(b));
 
-            System.out.println("---------- Books of Joana Nimar Updated Detached ------------");
+            System.out.println("\n---------- Books of Joana Nimar updated in detached state------------");
 
             // ,update first book title
-            books.get(0).setTitle("A History of Ancient Rome");
+            detachedBooks.get(0).setTitle("A History of Ancient Rome");
 
             // remove second title
-            books.remove(1);
+            detachedBooks.remove(1);
 
             // add a new book
             Book book = new Book();
             book.setTitle("History In 100 Minutes");
             book.setIsbn("005-JN");
-            books.add(book);
+            detachedBooks.add(book);
 
-            books.forEach(b -> System.out.println(b));
+            detachedBooks.forEach(b -> System.out.println(b));
 
-            System.out.println("----------------- Books of Joana Nimar Merged ----------------");
-            bookstoreService.updateBooksOfAuthor("Joana Nimar", books);
+            System.out.println("\n----------------- Merging books of Joana Nimar ----------------");
+            bookstoreService.updateBooksOfAuthor("Joana Nimar", detachedBooks);
 
+            System.out.println("\n----------------- Books of Joana Nimar After Merge ----------------");
+            List<Book> books = bookstoreService.fetchBooksOfAuthor("Joana Nimar");
+            
             books.forEach(b -> System.out.println(b));
         };
     }

HibernateSpringBootMergeCollections/src/main/java/com/bookstore/service/BookstoreService.java

@@ -34,14 +34,14 @@ public void updateBooksOfAuthor(String name, List<Book> detachedBooks) {
         System.out.println("-------------------------------------------------");
 
         // Remove the existing database rows that are no 
-        // longer found in the incoming collection (books)
-        List<Book> toRemove = author.getBooks().stream()
+        // longer found in the incoming collection (detachedBooks)
+        List<Book> booksToRemove  = author.getBooks().stream()
                 .filter(b -> !detachedBooks.contains(b))
                 .collect(Collectors.toList());
-        toRemove.forEach(b -> author.removeBook(b));
+        booksToRemove .forEach(b -> author.removeBook(b));
 
         // Update the existing database rows which can be found 
-        // in the incoming collection (books)
+        // in the incoming collection (detachedBooks)
         List<Book> newBooks = detachedBooks.stream()
                 .filter(b -> !author.getBooks().contains(b))
                 .collect(Collectors.toList());
@@ -52,8 +52,7 @@ public void updateBooksOfAuthor(String name, List<Book> detachedBooks) {
                     b.setAuthor(author);
                     Book mergedBook = bookRepository.save(b);
                     author.getBooks().set(
-                            author.getBooks().indexOf(mergedBook),
-                            mergedBook);
+                            author.getBooks().indexOf(mergedBook), mergedBook);
                 });
 
         // Add the rows found in the incoming collection,