كيف يتم التعامل مع Comparable interface

public class SalaryEmo extends EmployeeChapter8
{
private double salary1;

public SalaryEmo(String name, String address, int number, double salary1)
{
super(name, address, number);
setSalary1(salary1);

}

public void mailCheck()
{
System.out.println("Within mailCheck of SalaryEmo class");
System.out.println("Mailing check to " + getName() + " with salary " + salary1);
}

public double getSalary1()
{
return salary1;
}

public void setSalary1(double newSalary)
{
if(newSalary >= 0.0)
{
salary1 = newSalary;
}
}

public double computePay()
{
System.out.println("Computing salary pay for " + getName());
return salary1 / 52;
}
}

public class ComparbleSalaryEmo extends SalaryEmo implements Comparable {

public ComparbleSalaryEmo(String name, String address, int number, double salary1)
{
super(name, address, number, salary1);
}

public int compareTo(Object o)
{
if (getSalary1() > ((ComparbleSalaryEmo)o).getSalary1())
return 1;
else if (getSalary1() < ((ComparbleSalaryEmo)o).getSalary1())
return -1;
else
return 0;
}

public static void main(String[] args)
{
ComparbleSalaryEmo s1 = new ComparbleSalaryEmo("Ali", "Mariners", 5, 23.00);
ComparbleSalaryEmo s2 = new ComparbleSalaryEmo("Kalid", "Kingston", 4, 20.00);

System.out.println(s1.compareTo(s2));
System.out.println(s2.compareTo(s1));
}

}