java日期排序因该怎么写?（实例)谢谢！

import java.util.*;
public class EmployeeSortTest
{ public static void main(String[] args)
{ Employee5[] staff=new Employee5[3];
staff[0]=new Employee5("liyi",5000,1988,8,23);
staff[1]=new Employee5("wangli",4000,1988,5,17);
staff[2]=new Employee5("liwei",6000,1986,6,23);
Arrays.sort(staff);
for(Employee5 e:staff)
{ System.out.println("name="+e.getName()+",salary="+e.getSalary()+",hireDay="+e.getHireDay());
}
}
}
class Employee5 implements Comparable
{ public Employee5(String n,double s,int year,int month,int day)
{ name=n;
salary=s;
GregorianCalendar calendar=new GregorianCalendar(year,month,day);
hireDay=calendar.getTime();
}
public String getName()
{ return name;
}
public double getSalary()
{ return salary;
}
public Date getHireDay()
{ return hireDay;
}
public int compareTo(Employee5 other)
{ 这里应该怎么写？
}
private String name;
private Date hireDay;
private double salary;
}

public int compareTo(Employee5 other){
return this.getHireDay().compareTo(other.getHireDay());
}

input java.util.*; public class a { public static void main(string[] args){ int [] a = new int[5,4,7,12,6,78,24,1]; arrays.sort(a); system.out.println("排序后:"); for(int index=0; index<a.length;i++){ system.out.println(a[index]); } } }