(1)针对实验4编写的Staff类，分别编写NameComparator，AgeComparator和ComplexComparator比较器。其中ComplexComparator为复合比较器，至少选用两个关键字来排序，关键字选择、次序及升降序均由同学们自行设计。 (2)编写一个测试类，在测试类中添加若干个Staff, Teacher, SecurityGuard, Dean实例(个数及内容自定)，并在测试类中定义并测试如下方法：①编写一个方法private static void printName(Staff[] staffs)打印出每个人的名字；②编写一个方法private static void printSalary(Staff[] staffs)打印出Staff类或者其子类对象的薪水(注意：Staff的薪水只有salary，Teacher的薪水为salary+postAllowance，SecurityGuard的薪水为salary+dangerousAllowance，而Dean的薪水则为salary+postAllowance+adminAward)；③编写一方法private static void sortBySalary(Staff[] staffs)，支持对Staff类及其子类按照各自的薪水降序排序；④编写一方法private static void sortByAge(Staff[] staffs)，对Staff对象按照年龄升序排序，再编写一个方法按name升序进行排序；⑤编写一方法sortByDateHired，支持对Staff类及其子类按照各自的dateHired升序排序，可以使用java.util.Date类的getTime方法。

以下是代码实现： Staff.java ```java import java.util.Date; public class Staff { private String name; private int age; private Date dateHired; private double salary; public Staff(String name, int age, Date dateHired, double salary) { this.name = name; this.age = age; this.dateHired = dateHired; this.salary = salary; } public String getName() { return name; } public int getAge() { return age; } public Date getDateHired() { return dateHired; } public double getSalary() { return salary; } public void setSalary(double salary) { this.salary = salary; } @Override public String toString() { return "Staff{" + "name='" + name + '\'' + ", age=" + age + ", dateHired=" + dateHired + ", salary=" + salary + '}'; } } ``` Teacher.java ```java import java.util.Date; public class Teacher extends Staff { private double postAllowance; public Teacher(String name, int age, Date dateHired, double salary, double postAllowance) { super(name, age, dateHired, salary); this.postAllowance = postAllowance; } public double getPostAllowance() { return postAllowance; } public void setPostAllowance(double postAllowance) { this.postAllowance = postAllowance; } @Override public double getSalary() { return super.getSalary() + postAllowance; } @Override public String toString() { return "Teacher{" + "name='" + getName() + '\'' + ", age=" + getAge() + ", dateHired=" + getDateHired() + ", salary=" + getSalary() + '}'; } } ``` SecurityGuard.java ```java import java.util.Date; public class SecurityGuard extends Staff { private double dangerousAllowance; public SecurityGuard(String name, int age, Date dateHired, double salary, double dangerousAllowance) { super(name, age, dateHired, salary); this.dangerousAllowance = dangerousAllowance; } public double getDangerousAllowance() { return dangerousAllowance; } public void setDangerousAllowance(double dangerousAllowance) { this.dangerousAllowance = dangerousAllowance; } @Override public double getSalary() { return super.getSalary() + dangerousAllowance; } @Override public String toString() { return "SecurityGuard{" + "name='" + getName() + '\'' + ", age=" + getAge() + ", dateHired=" + getDateHired() + ", salary=" + getSalary() + '}'; } } ``` Dean.java ```java import java.util.Date; public class Dean extends Teacher { private double adminAward; public Dean(String name, int age, Date dateHired, double salary, double postAllowance, double adminAward) { super(name, age, dateHired, salary, postAllowance); this.adminAward = adminAward; } public double getAdminAward() { return adminAward; } public void setAdminAward(double adminAward) { this.adminAward = adminAward; } @Override public double getSalary() { return super.getSalary() + adminAward; } @Override public String toString() { return "Dean{" + "name='" + getName() + '\'' + ", age=" + getAge() + ", dateHired=" + getDateHired() + ", salary=" + getSalary() + '}'; } } ``` NameComparator.java ```java import java.util.Comparator; public class NameComparator implements Comparator<Staff> { @Override public int compare(Staff o1, Staff o2) { return o1.getName().compareTo(o2.getName()); } } ``` AgeComparator.java ```java import java.util.Comparator; public class AgeComparator implements Comparator<Staff> { @Override public int compare(Staff o1, Staff o2) { return Integer.compare(o1.getAge(), o2.getAge()); } } ``` ComplexComparator.java ```java import java.util.Comparator; public class ComplexComparator implements Comparator<Staff> { @Override public int compare(Staff o1, Staff o2) { if (o1.getSalary() == o2.getSalary()) { return o1.getDateHired().compareTo(o2.getDateHired()); } else { return Double.compare(o2.getSalary(), o1.getSalary()); } } } ``` TestStaff.java ```java import java.util.Arrays; import java.util.Date; public class TestStaff { public static void main(String[] args) { Staff[] staffs = { new Staff("Jack", 25, new Date(), 5000), new Teacher("Tom", 35, new Date(), 8000, 2000), new SecurityGuard("Jerry", 40, new Date(), 6000, 1000), new Dean("Rose", 45, new Date(), 10000, 3000, 4000) }; // 打印每个人的名字 printName(staffs); // 打印出Staff类或者其子类对象的薪水 printSalary(staffs); // 按照各自的薪水降序排序 sortBySalary(staffs); System.out.println("按照各自的薪水降序排序:"); for (Staff staff : staffs) { System.out.println(staff); } // 对Staff对象按照年龄升序排序，再按照name升序进行排序 sortByAge(staffs); System.out.println("对Staff对象按照年龄升序排序，再按照name升序进行排序:"); for (Staff staff : staffs) { System.out.println(staff); } // 对Staff类及其子类按照各自的dateHired升序排序 sortByDateHired(staffs); System.out.println("对Staff类及其子类按照各自的dateHired升序排序:"); for (Staff staff : staffs) { System.out.println(staff); } } private static void printName(Staff[] staffs) { System.out.println("每个人的名字:"); for (Staff staff : staffs) { System.out.println(staff.getName()); } System.out.println(); } private static void printSalary(Staff[] staffs) { System.out.println("Staff类或者其子类对象的薪水:"); for (Staff staff : staffs) { System.out.println(staff.getSalary()); } System.out.println(); } private static void sortBySalary(Staff[] staffs) { Arrays.sort(staffs, new Comparator<Staff>() { @Override public int compare(Staff o1, Staff o2) { return Double.compare(o2.getSalary(), o1.getSalary()); } }); } private static void sortByAge(Staff[] staffs) { Arrays.sort(staffs, new AgeComparator().thenComparing(new NameComparator())); } private static void sortByDateHired(Staff[] staffs) { Arrays.sort(staffs, new Comparator<Staff>() { @Override public int compare(Staff o1, Staff o2) { return o1.getDateHired().compareTo(o2.getDateHired()); } }); } } ```