Java Streams example with Real world scenario

streams/Employee.java

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+package streams;
+
+public class Employee {
+    private int id;
+    private String name;
+    private String dept;
+    private int age;
+    private double salary;
+    private boolean active;
+
+    public Employee(int id, String name, String dept, int age, double salary, boolean active) {
+        this.id = id;
+        this.name = name;
+        this.dept = dept;
+        this.age = age;
+        this.salary = salary;
+        this.active = active;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getDept() {
+        return dept;
+    }
+
+    public void setDept(String dept) {
+        this.dept = dept;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public double getSalary() {
+        return salary;
+    }
+
+    public void setSalary(double salary) {
+        this.salary = salary;
+    }
+
+    public boolean isActive() {
+        return active;
+    }
+
+    public void setActive(boolean active) {
+        this.active = active;
+    }
+}

streams/EmployeeAnalysis.java

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+package streams;
+
+/**
+ * Program Title: Java Streams example with Real world scenari
+ * Author: [hirushi1999]
+ * Date: 2025-10-14
+ * Demonstrates how to use Java Streams to perform data analysis on a list of employees.
+ * Scenario:
+ * - A company has employees working in various departments (HR, Engineering, Sales).
+ * - Each employee has attributes such as age, salary, and active status.
+ * Task:
+ * 1. Count how many employees fall into each age group.
+ * 2. Find the highest salary in each department among active employees.
+ * 3. List all active employees.
+ */
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+public class EmployeeAnalysis {
+    public static void main(String[] args) {
+        //Create list of employees
+        List<Employee> employeeList = Arrays.asList(
+                new Employee(1, "Alice", "HR", 25, 50000.0, true),
+                new Employee(2, "Bob", "Engineering", 35, 70000.0, false),
+                new Employee(3, "Charlie", "HR", 30, 55000.0, true),
+                new Employee(4, "David", "Engineering", 28, 72000.0, true),
+                new Employee(5, "Ella", "Sales", 26, 48000.0, true),
+                new Employee(6, "Frank", "Sales", 32, 49000.0, false),
+                new Employee(7, "Grace", "Engineering", 24, 69000.0, true),
+                new Employee(8, "Helen", "HR", 22, 51000.0, false),
+                new Employee(9, "Ian", "Sales", 27, 47000.0, true));
+
+        System.out.println("------------------------------------------------------");
+        System.out.println("1.Count how many employees fall into each age group");
+        Map<String, Long> countAgeRange = employeeList.stream()
+                .collect(Collectors.groupingBy(e -> getAgeGroup(e.getAge()).toString(), Collectors.counting()));
+
+        countAgeRange.forEach((k, v) -> { System.out.println(k + ": " + v); });
+
+        System.out.println("------------------------------------------------------");
+        System.out.println("2. Find the highest salary in each department among active employees");
+        Map<String, Optional<Employee>> highestsal = employeeList.stream()
+                .filter(Employee::isActive)
+                .collect(Collectors.groupingBy(Employee::getDept,
+                        Collectors.maxBy(Comparator.comparingDouble(Employee::getSalary))));
+
+        highestsal.forEach((k, v) -> {
+            System.out.println(k + ": " + v.get().getName() + ": " + v.get().getSalary());
+        });
+
+        System.out.println("------------------------------------------------------");
+        System.out.println("3. List all active employees");
+        List<Employee> ActiveEmp = employeeList.stream().filter(Employee::isActive).collect(Collectors.toList());
+        for (Employee e : ActiveEmp) {
+            System.out.print(e.getName() + ", ");
+        }
+
+    }
+
+    private static Object getAgeGroup(int age) {
+        if(age>=20 && age<=29){
+            return "20-29";
+        } else if (age>=30 && age<=39) {
+            return "30-39";
+        } else {
+            return "+40";
+        }
+    }
+}