Definition
Filter employees under retirement age, then find the one with the highest age (closest to 60) using max(comparingInt(age)).
- RETIREMENT_AGE = 60 as a named constant.
- filter(age < 60) excludes already-retired employees.
- max(comparingInt(age)) among the filtered set finds the employee closest to retirement.
- Equivalently:
min(comparingInt(e -> RETIREMENT_AGE - e.getAge()))finds the smallest gap.
The bank's succession planning team asks: 'Who is about to retire?' Find the employee under 60 with the highest age, because they are the closest to the retirement line.
Understanding the Concepts
How do you find the employee closest to retirement?
JAVA
package com.bank.hr;
import java.util.*;
public class ClosestToRetirement {
private static final int RETIREMENT_AGE = 60;
public static void main(String[] args) {
List<Employee> employees = Employee.getSampleEmployees();
Optional<Employee> closest = employees.stream()
.filter(e -> e.getAge() < RETIREMENT_AGE)
.max(Comparator.comparingInt(Employee::getAge));
closest.ifPresent(e ->
System.out.printf("%s, age %d, retires in %d years%n",
e.getName(), e.getAge(),
RETIREMENT_AGE - e.getAge()));
}
}
TEXT
Suresh, age 58, retires in 2 years
How do you list all employees retiring within 5 years?
JAVA
List<Employee> retiringWithin5 = employees.stream()
.filter(e -> e.getAge() >= RETIREMENT_AGE - 5
&& e.getAge() < RETIREMENT_AGE)
.sorted(Comparator.comparingInt(Employee::getAge).reversed())
.toList();
What are common mistakes?
Mistake: not excluding employees already at or past retirement age.
JAVA
// WRONG: includes employees already aged 60+
Optional<Employee> wrong = employees.stream()
.max(Comparator.comparingInt(Employee::getAge));
// Could return someone aged 62 who is already retired!
// CORRECT: filter first
Optional<Employee> correct = employees.stream()
.filter(e -> e.getAge() < RETIREMENT_AGE)
.max(Comparator.comparingInt(Employee::getAge));
What about finding the closest to retirement per department?
JAVA
Map<String, Optional<Employee>> closestPerDept = employees.stream()
.filter(e -> e.getAge() < RETIREMENT_AGE)
.collect(Collectors.groupingBy(
Employee::getDepartment,
Collectors.maxBy(
Comparator.comparingInt(Employee::getAge))));
What about listing employees retiring within N years?
JAVA
public static List<Employee> retiringWithin(
List<Employee> employees, int years) {
return employees.stream()
.filter(e -> e.getAge() >= RETIREMENT_AGE - years
&& e.getAge() < RETIREMENT_AGE)
.sorted(Comparator.comparingInt(Employee::getAge).reversed())
.toList();
}
What about variable retirement age by role?
JAVA
Map<String, Integer> retirementAges = Map.of(
"TRADING", 60, "OPERATIONS", 62, "RISK", 58);
Optional<Employee> closest = employees.stream()
.filter(e -> e.getAge() < retirementAges
.getOrDefault(e.getDepartment(), 60))
.max(Comparator.comparingInt(e ->
e.getAge() - retirementAges
.getOrDefault(e.getDepartment(), 60)));
What are the edge cases?
If all employees are already past retirement age, the filter produces an empty stream and the result is Optional.empty(). An employee exactly at retirement age (age == 60) is excluded by the strict less-than filter.
What are common interview follow-up questions?
- "How do you find the closest to retirement per department?" Use groupingBy(dept, collectingAndThen(filtering(age < 60), maxBy(comparingInt(age)))).
- "What if retirement age varies by role?" Accept a Function
Visual Overview
DIAGRAM
RETIREMENT_AGE = 60 filter(age < 60) then max(age): ┌──────────────────────────────────────────┐ │ Rajesh 45 → 60-45 = 15 years left │ │ Suresh 58 → 60-58 = 2 years left ← min│ │ Deepak 55 → 60-55 = 5 years left │ │ Vikram 52 → 60-52 = 8 years left │ │ Priya 28 → 60-28 = 32 years left │ └──────────────────────────────────────────┘ → Suresh (58) is closest to retirement
Key Takeaway
Finding the employee closest to retirement filters for those under the retirement age, then finds the maximum age in the remaining set. The employee with the highest age below 60 has the fewest years until retirement.
Remember one sentence: filter for age under retirement, then max by age to find who is closest to the retirement line.
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