java中Comparator自定义排序

╰+哭是因爲堅強的太久メ 2022-05-18 05:57 236阅读 0赞

java中Comparator自定义排序：  
Comparator接口可以实现自定义排序，实现Comparator接口时，要重写compare方法：  
int compare(Object o1, Object o2) 返回一个基本类型的整型  
如果要按照升序排序,则o1 小于o2，返回-1（负数），相等返回0，01大于02返回1（正数）  
如果要按照降序排序,则o1 小于o2，返回1（正数），相等返回0，01大于02返回-1（负数）  
\*\*定义一个Person类，属性为姓名name，学号number,年龄age,性别sex,身高height,体重weigth，自定义排序规则为：  
性别男优先  
年龄从小到大  
体重从低到高  
身高从高到低  
姓名字数从少到多\*\*  
**Person.java**

public class Person { 
        private String name;
        private String number;
        private int age;
        private String sex;
        private double height;
        private double weigth;
        public Person() {
            super();
        }
        public Person(String name, String number, int age, String sex, double height, double weigth) {
            super();
            this.name = name;
            this.number = number;
            this.age = age;
            this.sex = sex;
            this.height = height;
            this.weigth = weigth;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getNumber() {
            return number;
        }
        public void setNumber(String number) {
            this.number = number;
        }
        public int getAge() {
            return age;
        }
        public void setAge(int age) {
            this.age = age;
        }
        public String getSex() {
            return sex;
        }
        public void setSex(String sex) {
            this.sex = sex;
        }
        public double getHeight() {
            return height;
        }
        public void setHeight(double height) {
            this.height = height;
        }
        public double getWeigth() {
            return weigth;
        }
        public void setWeigth(double weigth) {
            this.weigth = weigth;
        }
        @Override
        public String toString() {
            return "Person [name=" + name + ", number=" + number + ", age=" + age + ", sex=" + sex + ", height=" + height
                    + ", weigth=" + weigth + "]";
        }
    }

--------------------

**PersonTest.java**

第一种方法：

public class PersonTest {
    public static void main(String[] args) {
        List<Person> list=new LinkedList<Person>();
          list.add(new Person("钟爱", "201508020114", 21, "女", 162.01, 80.03));
          list.add(new Person("张大旗", "20150802", 22, "女", 159.99, 102.34));
          list.add(new Person("王大拿里哦", "20150802012", 20, "男", 182.01, 132));
          list.add(new Person("张三", "201501", 18, "男", 144, 112));
          list.add(new Person("张原野", "201505", 19, "女", 120, 144));
          list.add(new Person("李冬梅子", "201503", 20, "男", 189, 122));
          list.add(new Person("田园圣诞", "201504",20, "男", 189, 132));
          list.add(new Person("李很帅", "201502", 17, "男", 173, 132));
    
        for (Person person : list) {
            System.out.println("排序前"+person);
        }
        System.out.println("========================================================================");
        list.sort(new Comparator<Person>() {
            int flag=0;
            @Override
            public int compare(Person o1, Person o2) {
                int a=o1.getSex().compareTo(o2.getSex());
                if(a!=0&&a>0){
                    return -1;
                        }
                else if(o1.getSex().equals(o2.getSex())){
                    if(o1.getAge()<o2.getAge()){
                        return -1;
                    }
                    else if(o1.getAge()==o2.getAge()){
                        if(o1.getWeigth()<o2.getWeigth()){
                            return -1;
                        }
                        else if(o1.getWeigth()==o2.getWeigth()){
                            if(o1.getHeight()>o2.getHeight()){
                                return -1;
                            }
                            else if(o1.getHeight()==o2.getHeight()){
                                if(o1.getName().length()<o2.getName().length()){
                                    return -1;
                                }
                            }
                        }
                    }
                }
                return 1;
            }
        });
        for (Person person1 : list) {
            System.out.println("排序后"+person1);
        }
        }
        }

--------------------

第二种方法：

public class PersonTest {
    public static void main(String[] args) {
        List<Person> list=new LinkedList<Person>();
          list.add(new Person("钟爱", "201508020114", 21, "女", 162.01, 80.03));
          list.add(new Person("张大旗", "20150802", 22, "女", 159.99, 102.34));
          list.add(new Person("王大拿里哦", "20150802012", 20, "男", 182.01, 132));
          list.add(new Person("张三", "201501", 18, "男", 144, 112));
          list.add(new Person("张原野", "201505", 19, "女", 120, 144));
          list.add(new Person("李冬梅子", "201503", 20, "男", 189, 122));
          list.add(new Person("田园圣诞", "201504",20, "男", 189, 132));
          list.add(new Person("李很帅", "201502", 17, "男", 173, 132));
        for (Person person : list) {
            System.out.println("排序前"+person);
        }
        System.out.println("===============================================");
        list.sort(new Comparator<Person>() {
             int flag = 0;
            int a = o1.getSex().compareTo(o2.getSex());
            if (!(0 == a)) {
                flag = (a > 0 ? 1 : -1);
            } else {
                a = o1.getAge() - o2.getAge();
                if (a != 0) {
                    flag = (a > 0 ? 1 : -1);
                } else {
                    a = (int) (o2.getWeight()- o1.getWeight());
                    if (a != 0) {
                        flag = (a > 0 ? 1 : -1);
                    } else {
                         a = (int) (o1.getHeight() - o2.getHeight());
                        if (a != 0) {
                            flag = (a > 0 ? 1 : -1);
                        } else {
                             a = (int) (o2.getName().length() - o1.getName().length());
                            flag = (a > 0 ? 1 : -1);
                        }
                    }
                }
            }
            return -flag;
            }
            }

--------------------

输出结果截图：  
![这里写图片描述][70]

[70]: /images/20220518/2c1682bf9c844a4fbeaf4b0d90d24358.png