Sorting a collection by more than one field

Let's say we have an Employee Object with the fields as given below.

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class Employee implements Comparable {       private int empid;     private String deptname;     private String name;     private float salary;       public int getEmpid() {         return empid;     }       public String getDeptname() {         return deptname;     }       public String getName() {         return name;     }       public float getSalary() {         return salary;     }       public Employee(int empid, String deptname, String name, float salary) {         this.empid = empid;         this.deptname = deptname;         this.name = name;         this.salary = salary;     }       @Override     public String toString() {         return "Employee{" + "empid=" + empid + ", deptname=" + deptname + ", name=" + name + ", salary=" + salary + '}' + "\n";     }       @Override     public int hashCode() {         int hash = 3;         hash = 23 * hash + this.empid;         return hash;     }       @Override     public boolean equals(Object obj) {         if (obj == null) {             return false;         }         if (getClass() != obj.getClass()) {             return false;         }         final Employee other = (Employee) obj;         if (this.empid != other.empid) {             return false;         }         return true;     }       @Override     public int compareTo(Object o) {         if (o instanceof Employee) {             Employee other = (Employee) o;             return this.name.compareTo(other.name);         } else {             throw new RuntimeException("Comparison object is not matching");         }     } }

Requirement: We want to sort Employee objects first by deptname and then followed by employee name within each department.

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public class MultipleSort {       public static void main(String[] args) {         List<employee> emplist = new ArrayList<employee>();         emplist.add(new Employee(353744, "MCA", "Athiruban", 47000));         emplist.add(new Employee(311344, "CSE", "Nandhini", 41000));         emplist.add(new Employee(351144, "EEE", "Kishore", 44400));         emplist.add(new Employee(353321, "MCA", "Karthik", 37000));         emplist.add(new Employee(353711, "CSE", "Gopal", 37000));         emplist.add(new Employee(353743, "IT", "AthiNivas", 67000));           defaultSortandDisplay(emplist);         sortByDeptAndThenByName(emplist);     }       private static void defaultSortandDisplay(List<employee> emplist) {         Collections.sort(emplist);         System.out.println("DefaultSortandDisplay->\n" + emplist);     }       private static void sortByDeptAndThenByName(List<employee> emplist) {         Map<string, list<employee="">> mapSortedByDept = new TreeMap<string, list<employee="">>();         List<employee> finallist = new ArrayList<employee>();         for (Employee e : emplist) {             if (mapSortedByDept.containsKey(e.getDeptname()) == true) {                 mapSortedByDept.get(e.getDeptname()).add(e);             } else {                 List templist = new ArrayList<employee>();                 templist.add(e);                 mapSortedByDept.put(e.getDeptname(), templist);             }         }         System.out.println("Ordered by Department->\n" + mapSortedByDept);           Collection<list<employee>> collectionSortedByDept = mapSortedByDept.values();         for (List indvlist : collectionSortedByDept) {             Collections.sort(indvlist);             finallist.addAll(indvlist);         }         System.out.println("Ordered by name within Department->\n" + mapSortedByDept);         System.out.println("Final list->\n" + finallist);     } }   </list<employee></employee></employee></employee></string,></string,></employee></employee></employee></employee>