Lesson 8

lessons/src/main/java/lessons/lesson08/App.java

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+package Lesson8;
+
+import java.util.*;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+/**
+ * @author Shohjahon
+ * @version 1.0
+ */
+
+public class App {
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+        Queue<User> userQueue = new LinkedList<>();
+        int[] sequenceCounter = {1};
+
+        System.out.println("Enter user names (type 'done' to finish):");
+
+        Stream.generate(() -> {
+                    System.out.print("Enter user name: ");
+                    return scanner.nextLine().trim();
+                })
+                .takeWhile(name -> !name.equalsIgnoreCase("done"))
+                .forEach(name -> {
+                    User user = new User(name, sequenceCounter[0]++);
+                    userQueue.add(user);
+                    System.out.println("Added to queue: " + user);
+                });
+
+        Optional.ofNullable(userQueue.poll())
+                .ifPresentOrElse(
+                        user -> System.out.println("Processing user: " + user),
+                        () -> System.out.println("No users to process.")
+                );
+
+        System.out.println("\nEnter a series of numbers separated by spaces:");
+        String input = scanner.nextLine();
+
+        Set<Integer> uniqueNumbers = Arrays.stream(input.split("\\s+"))
+                .filter(s -> s.matches("\\d+"))
+                .map(Integer::parseInt)
+                .collect(Collectors.toCollection(LinkedHashSet::new));
+
+        System.out.println("Unique numbers: " + uniqueNumbers);
+
+        Map<String, Book> bookMap = Stream.of(
+                new Book("1984", "George Orwell", "978-0451524935"),
+                new Book("The Odyssey", "Homer", "978-0140449266"),
+                new Book("To Kill a Mockingbird", "Harper Lee", "978-0061120084")
+        ).collect(Collectors.toMap(Book::getIsbn, b -> b));
+
+        System.out.println("\nBooks in library:");
+        bookMap.values().forEach(System.out::println);
+
+        scanner.close();
+    }
+}

lessons/src/main/java/lessons/lesson08/Book.java

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+package Lesson8;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+class Book {
+    private String name;
+    private String author;
+    private String isbn;
+}

lessons/src/main/java/lessons/lesson08/User.java

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+package Lesson8;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+class User {
+    private String name;
+    private int sequenceNumber;
+}