Advanced Java

⚙ Streams — Factory Assembly Line (5–20 min)

💻 Live Coding — Student Pipeline (20–40 min)

import java.util.*;
import java.util.stream.*;

record Student(String name, int marks, String dept) {}

public class StreamDemo {
    public static void main(String[] args) {
        List<Student> students = List.of(
            new Student("Priya", 92, "CS"),
            new Student("Ravi",  45, "IT"),
            new Student("Anita", 78, "CS"),
            new Student("Meena", 88, "CS")
        );

        // CS students who passed, sorted by marks desc
        List<String> result = students.stream()
            .filter(s -> s.dept().equals("CS"))
            .filter(s -> s.marks() >= 60)
            .sorted((a,b) -> b.marks() - a.marks())
            .map(Student::name)
            .collect(Collectors.toList());

        System.out.println(result);  // [Meena, Anita, Priya]

        double avg = students.stream()
            .mapToInt(Student::marks).average().orElse(0);
        System.out.println("Avg: " + avg);
    }
}

🛡 Optional — Never NullPointerException Again

// Safe with Optional:
Optional<User> user = repo.findById(id);
user.ifPresent(u -> System.out.println(u.getName()));
String name = user.map(User::getName).orElse("Unknown");
User u = user.orElseThrow(() -> new RuntimeException("Not found"));