Given a list of employees, how do you find the highest paid using Java 8 Streams?

public class Employee {
    private String name;
    private String department;
    private double salary;
    private String role;
    private int yearsOfExp;

    public Employee(String name, String department, double salary, String role, int exp) {
        this.name = name; this.department = department;
        this.salary = salary; this.role = role; this.yearsOfExp = exp;
    }
    // Getters omitted for brevity
}

List<Employee> employees = Arrays.asList(
    new Employee("Alice",   "QA",      95000, "SDET",    5),
    new Employee("Bob",     "Dev",     120000, "Engineer", 8),
    new Employee("Charlie", "QA",      85000, "SDET",    3),
    new Employee("Diana",   "Dev",     135000, "Lead",    10),
    new Employee("Eve",     "QA",      110000, "Manager", 7),
    new Employee("Frank",   "Dev",     90000, "Engineer", 4)
);

// Using max() — most efficient
Optional<Employee> highestPaid = employees.stream()
    .max(Comparator.comparingDouble(Employee::getSalary));

highestPaid.ifPresent(e ->
    System.out.println("Highest paid: " + e.getName() + " - $" + e.getSalary()));
// "Highest paid: Diana - $135000.0"

// Group by department, find max salary in each
Map<String, Optional<Employee>> highestPerDept = employees.stream()
    .collect(Collectors.groupingBy(
        Employee::getDepartment,
        Collectors.maxBy(Comparator.comparingDouble(Employee::getSalary))
    ));

highestPerDept.forEach((dept, emp) ->
    emp.ifPresent(e -> System.out.println(dept + ": " + e.getName() + " $" + e.getSalary())));
// Dev: Diana $135000.0
// QA: Eve $110000.0

List<Employee> top3 = employees.stream()
    .sorted(Comparator.comparingDouble(Employee::getSalary).reversed())
    .limit(3)
    .collect(Collectors.toList());

top3.forEach(e -> System.out.println(e.getName() + ": $" + e.getSalary()));
// Diana: $135000.0, Bob: $120000.0, Eve: $110000.0

Map<String, Double> avgByDept = employees.stream()
    .collect(Collectors.groupingBy(
        Employee::getDepartment,
        Collectors.averagingDouble(Employee::getSalary)
    ));

avgByDept.forEach((dept, avg) ->
    System.out.printf("%s avg: $%.0f%n", dept, avg));
// Dev avg: $115000, QA avg: $96667

double avg = employees.stream()
    .mapToDouble(Employee::getSalary)
    .average()
    .orElse(0);

List<Employee> aboveAvg = employees.stream()
    .filter(e -> e.getSalary() > avg)
    .sorted(Comparator.comparingDouble(Employee::getSalary).reversed())
    .collect(Collectors.toList());

System.out.println("Average: $" + avg);
aboveAvg.forEach(e -> System.out.println(e.getName() + ": $" + e.getSalary()));

Map<String, Long> countByDept = employees.stream()
    .collect(Collectors.groupingBy(Employee::getDepartment, Collectors.counting()));
// {QA=3, Dev=3}

DoubleSummaryStatistics stats = employees.stream()
    .mapToDouble(Employee::getSalary)
    .summaryStatistics();

System.out.println("Max: $"   + stats.getMax());
System.out.println("Min: $"   + stats.getMin());
System.out.println("Avg: $"   + stats.getAverage());
System.out.println("Sum: $"   + stats.getSum());
System.out.println("Count: "  + stats.getCount());