Model an Employee Directory (Maps)

public class Employee {
    private String employeeId;
    private String name;
    private String department;

    public Employee(String employeeId, String name, String department) {
        this.employeeId = employeeId;
        this.name = name;
        this.department = department;
    }

    public String getEmployeeId() { return employeeId; }
    public String getName() { return name; }
    public String getDepartment() { return department; }
}

This is Module 16's wrapper class pattern combined with Module 10's encapsulation — private fields, set once through the constructor, exposed through controlled getters.

public class EmployeeDirectory {
    private Map<String, Employee> employeesById = new Map<String, Employee>();

    public void addEmployee(Employee emp) {
        employeesById.put(emp.getEmployeeId(), emp);
    }

    public Employee getEmployee(String employeeId) {
        return employeesById.get(employeeId);
    }

    public Integer getEmployeeCount() {
        return employeesById.size();
    }
}

This is exactly Module 16's Map<Id, sObject> pattern, applied to a custom Employee type instead of a real Salesforce record — one put() per employee, and any lookup afterward is instant, regardless of how many employees the directory holds.

EmployeeDirectory directory = new EmployeeDirectory();

directory.addEmployee(new Employee('E001', 'Amara Nkosi', 'Engineering'));
directory.addEmployee(new Employee('E002', 'Ben Dlamini', 'Sales'));

Employee found = directory.getEmployee('E001');
System.debug(found.getName()); // "Amara Nkosi"
System.debug(directory.getEmployeeCount()); // 2

No looping required to find E001 — the Map inside EmployeeDirectory handles the lookup directly, exactly the performance benefit highlighted back in Module 16's "Maps" lesson.