From 5d0cc83bfd679aa959350988b741c228bdfdad1b Mon Sep 17 00:00:00 2001
From: SteffenLm <33038091+SteffenLm@users.noreply.github.com>
Date: Thu, 5 Jun 2025 14:55:46 +0200
Subject: [PATCH 1/2] Solution Optionals 02

---
 BookCollection.java | 11 ++++++-----
 Exercise.java       |  8 ++++++--
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/BookCollection.java b/BookCollection.java
index 688804d..cf8ec96 100644
--- a/BookCollection.java
+++ b/BookCollection.java
@@ -1,6 +1,7 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Optional;
 import java.util.Map.Entry;
 
 public record BookCollection(HashMap<Author, List<Book>> collection) {
@@ -17,18 +18,18 @@ public void addBook(Author author, Book book) {
     collection.get(author).add(book);
   }
 
-  public Book getBookByTitle(String title) {
+  public Optional<Book> getBookByTitle(String title) {
     for (List<Book> books : collection.values()) {
       for (Book b : books) {
         if (b.title().equals(title)) {
-          return b;
+          return Optional.of(b);
         }
       }
     }
-    return null;
+    return Optional.empty();
   }
 
-  public Author getMostDiligentAuthor() {
+  public Optional<Author> getMostDiligentAuthor() {
     Author mostDiligentAuthor = null;
     int mostBooks = 0;
     for (Entry<Author, List<Book>> entry : collection.entrySet()) {
@@ -37,6 +38,6 @@ public Author getMostDiligentAuthor() {
         mostBooks = entry.getValue().size();
       }
     }
-    return mostDiligentAuthor;
+    return Optional.ofNullable(mostDiligentAuthor);
   }
 }
diff --git a/Exercise.java b/Exercise.java
index 14125d0..5dbb4e3 100644
--- a/Exercise.java
+++ b/Exercise.java
@@ -21,7 +21,11 @@ public static void main(String[] args) {
     collection.addBook(new Author("George RR Martin"), new Book("Das Lied von Eis und Feuer 5"));
     collection.addBook(new Author("George RR Martin"), new Book("Das Lied von Eis und Feuer 6"));
 
-    System.out.println(collection.getBookByTitle("Das Lied von Eis und Feuer 5"));
-    System.out.println(collection.getMostDiligentAuthor());
+    collection.getBookByTitle("Das Lied von Eis und Feuer 5")
+        .ifPresentOrElse(System.out::println,
+            () -> System.out.println("Das gesuchte Buch ist nicht vorhanden"));
+    collection.getMostDiligentAuthor()
+        .ifPresentOrElse(System.out::println,
+            () -> System.out.println("Es ist kein entsprechender Autor vorhanden"));
   }
 }

From a8d2343d0a31d9bee16f7910c029d77e00fdf8b5 Mon Sep 17 00:00:00 2001
From: github-actions <>
Date: Thu, 5 Jun 2025 12:56:23 +0000
Subject: [PATCH 2/2] Google Java Format

---
 BookCollection.java |  2 +-
 Exercise.java       | 13 ++++++++-----
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/BookCollection.java b/BookCollection.java
index cf8ec96..b7a725d 100644
--- a/BookCollection.java
+++ b/BookCollection.java
@@ -1,8 +1,8 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
-import java.util.Optional;
 import java.util.Map.Entry;
+import java.util.Optional;
 
 public record BookCollection(HashMap<Author, List<Book>> collection) {
 
diff --git a/Exercise.java b/Exercise.java
index 5dbb4e3..93d42f9 100644
--- a/Exercise.java
+++ b/Exercise.java
@@ -21,11 +21,14 @@ public static void main(String[] args) {
     collection.addBook(new Author("George RR Martin"), new Book("Das Lied von Eis und Feuer 5"));
     collection.addBook(new Author("George RR Martin"), new Book("Das Lied von Eis und Feuer 6"));
 
-    collection.getBookByTitle("Das Lied von Eis und Feuer 5")
-        .ifPresentOrElse(System.out::println,
-            () -> System.out.println("Das gesuchte Buch ist nicht vorhanden"));
-    collection.getMostDiligentAuthor()
-        .ifPresentOrElse(System.out::println,
+    collection
+        .getBookByTitle("Das Lied von Eis und Feuer 5")
+        .ifPresentOrElse(
+            System.out::println, () -> System.out.println("Das gesuchte Buch ist nicht vorhanden"));
+    collection
+        .getMostDiligentAuthor()
+        .ifPresentOrElse(
+            System.out::println,
             () -> System.out.println("Es ist kein entsprechender Autor vorhanden"));
   }
 }