Remove duplicates from a sorted list - Java

public class RemoveDuplicatesFromSortedList {
public static void main(String[] args) {
ArrayList<String> al = new ArrayList<String>(); al.add("ab"); al.add("ab"); al.add("ac"); al.add("bv"); al.add("bv"); al.add("bz"); al.add("ca"); al.add("ca");
ArrayList<String> sl =removeDuplicates(al); for (String s : sl) {
System.out.println(s); }
}
private static ArrayList<String> removeDuplicates(ArrayList<String> al) {
TreeSet<String> ts = new TreeSet<String>(); ts.addAll(al); al.clear(); al.addAll(ts); return al; }
}

Employee...

public class RemovesDuplicates {
    public static void main(String[] args) {
        Employee e1 = new Employee();        e1.setName("aa").setSalary(1000);
        Employee e11 = new Employee();        e11.setName("aa").setSalary(1000);
        Employee e2 = new Employee();        e2.setName("bb").setSalary(2000);
        Employee e3 = new Employee();        e3.setName("cc").setSalary(3000);
        Employee e33 = new Employee();        e33.setName("cc").setSalary(3000);
        Employee e4 = new Employee();        e4.setName("dd").setSalary(4000);
        ArrayList<Employee> al = new ArrayList<Employee>();        al.add(e1);        al.add(e11);        al.add(e2);        al.add(e3);        al.add(e4);
        ArrayList<Employee> sl = removeDuplicates(al);
        for (Employee employee : sl) {
            System.out.println(employee.toString());        }

    }

    private static ArrayList<Employee> removeDuplicates(ArrayList<Employee> al) {
        TreeSet<Employee> ts = new TreeSet<Employee>();        ts.addAll(al);        al.clear();        al.addAll(ts);        return al;    }
}

class Employee implements Comparable<Employee>{

    String name;    int salary;
    public String getName() {
        return name;    }

    public Employee setName(String name) {
        this.name = name;        return this;    }

    public int getSalary() {
        return salary;    }

    public Employee setSalary(int salary) {
        this.salary = salary;        return this;    }

    @Override    public int compareTo(Employee e) {
        if(e.salary > salary)
            return -1;        else if(e.salary == salary)
            return 0;        else return 1;    }

    @Override    public boolean equals(Object o) {
        if (this == o) return true;        if (o == null || getClass() != o.getClass()) return false;
        Employee employee = (Employee) o;
        if (salary != employee.salary) return false;        return !(name != null ? !name.equals(employee.name) : employee.name != null);
    }

    @Override    public int hashCode() {
        int result = name != null ? name.hashCode() : 0;        result = 31 * result + salary;        return result;    }

    @Override    public String toString() {
        return "Employee{" +
                "name='" + name + '\'' +
                ", salary=" + salary +
                '}';    }
}