## 概述
接口就是对已有类的功能进行扩展.
```
public class Employee implements Comparable<Employee>
{
private String name;
private double salary;
public Employee(String name, double salary)
{
this.name = name;
this.salary = salary;
}
public void raiseSalary(double byPrecent)
{
double raise = this.salary * byPrecent / 100;
this.salary += raise;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public double getSalary()
{
return salary;
}
public void setSalary(double salary)
{
this.salary = salary;
}
@Override
public int compareTo(Employee o)
{
return Double.compare(this.salary, o.salary);
}
}
```
测试
~~~
import java.util.Arrays;
public class EmployeeSortTest
{
public static void main(String[] args)
{
Employee[] staff = new Employee[3];
staff[0] = new Employee("jack", 20);
staff[1] = new Employee("milan", 40);
staff[2] = new Employee("mike", 30);
Arrays.sort(staff);
for (Employee e : staff) {
System.out.println("name = " + e.getName() + ", salary = " + e.getSalary());
}
}
}
~~~
