Comparartor.java

Follow this code to sort any ArrayList

Collections.sort(empList, new Comparator<Employee>(){
    public int compare(Employee emp1, Employee emp2) {
        // ## Ascending order
        return emp1.getFirstName().compareToIgnoreCase(emp2.getFirstName()); // To compare string values
        // return Integer.valueOf(emp1.getId()).compareTo(emp2.getId()); // To compare integer values

        // ## Descending order
        // return emp2.getFirstName().compareToIgnoreCase(emp1.getFirstName()); // To compare string values
        // return Integer.valueOf(emp2.getId()).compareTo(emp1.getId()); // To compare integer values
        }
    })