Java基础进阶集合-Comparable接口，Comparator比较器案例

小咪咪 2023-10-08 16:51 24阅读 0赞

定义一个Employee类

该类包括：

*  private 成员变量 name ,age,birthday,其中birthday为MyDate类的对象
 *  并为每一个属性定义getter setter方法

定义Mydate类包含：

*  private 成员变量 year,month,day 并为每一个属性定义getter setter方法

创建该Employee类的5个对象，并把这些对象放入TreeSet集合中，分别按以下两种方式对集合中的元素进行排序，并遍历输出

(1)使Employee实现Comparable接口，并按name排序，字典表顺序

(2)创建TreeSet时传入Comparator对象，按生日日期的对员工进行先后顺序排序

1992 - 05 - 12

1992 - 05 - 18

1992 - 07 - 15

1993 - 06 - 15

1998 - 02 - 03

#### ①Emoplyee.java ####

public class Employee implements Comparable<Employee>{
        
    
        private String name;;
        private int age;
        private MyDate birthday;
    
        public Employee(){
        }
    
        public Employee(int age){
        
            this.age = age;
        }
        public Employee(String name){
        this.name = name;}
    
        public Employee(String name, int age, MyDate birthday) {
        
            this.name = name;
            this.age = age;
            this.birthday = birthday;
        }
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public int getAge() {
        
            return age;
        }
    
        public void setAge(int age) {
        
            this.age = age;
        }
    
        public MyDate getBirthday() {
        
            return birthday;
        }
    
        public void setBirthday(MyDate birthday) {
        
            this.birthday = birthday;
        }
    
    
        @Override
        public int compareTo(Employee e) {
        
    
            if(this.getAge() == e.getAge()) {
        
                return this.getName().compareTo(e.getName());
            }else{
        
                return this.getAge() - e.getAge();
            }
        }
    
        @Override
        public String toString() {
        
            return "Employee{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    ", birthday=" + birthday +
                    '}';
        }
    }

#### ②MyDate.java ####

public class MyDate {
        
        private int year;
        private int month;
        private int day;
    
        public MyDate(){
        
    
        }
    
        public MyDate(int year, int month, int day) {
        
            this.year = year;
            this.month = month;
            this.day = day;
        }
    
        public int getYear() {
        
            return year;
        }
    
        public void setYear(int year) {
        
            this.year = year;
        }
    
        public int getMonth() {
        
            return month;
        }
    
        public void setMonth(int month) {
        
            this.month = month;
        }
    
        public int getDay() {
        
            return day;
        }
    
        public void setDay(int day) {
        
            this.day = day;
        }
    
        @Override
        public String toString() {
        
            return "MyDate{" +
                    "year=" + year +
                    ", month=" + month +
                    ", day=" + day +
                    '}';
        }
    }

#### ③Test.java ####

public class Test {
        
        public static void main(String[] args) {
        
    
            //创建TreeSet集合对象
            TreeSet<Employee> set = new TreeSet<>(new Comparator<Employee>() {
        //比较器比较生日
                @Override
                public int compare(Employee o1, Employee o2) {
        
    
                    int year = o1.getBirthday().getYear();
                    int month = o1.getBirthday().getMonth();
                    int day = o1.getBirthday().getDay();
    
                    int year1 = o2.getBirthday().getYear();
                    int month1 = o2.getBirthday().getMonth();
                    int day1 = o2.getBirthday().getDay();
    
                    int result = year - year1;
                    int result2 = result == 0  ? month - month1 : result ;
                    int result3 = result2 ==0 ? day - day1 : result2;
                    return result3;
                }
            });
    
            //创建Empployee对象
            Employee e1 = new Employee("zhangsan",20,new MyDate(1992,05,12));
            Employee e2 = new Employee("lisi",18,new MyDate(1992,05,18));
            Employee e3 = new Employee("wangwu",18,new MyDate(1992,07,15));
            Employee e4 = new Employee("zhaoliu",13,new MyDate(1992,05,12));
            Employee e5 = new Employee("xuqi",80,new MyDate(1993,06,15));
    
            //把Employee对象放到TreeSet集合中
            set.add(e1);
            set.add(e2);
            set.add(e3);
            set.add(e4);
            set.add(e5);
    
            //遍历
            for(Employee e : set){
        
                System.out.println(e);
            }
    
    
    
        }
    }

#### 测试结果: ####

![在这里插入图片描述][02235f0792c243fdbf303ebe220670ab.png]

[02235f0792c243fdbf303ebe220670ab.png]: https://img-blog.csdnimg.cn/02235f0792c243fdbf303ebe220670ab.png