TreeMap类型实体类数据进行排序

川长思鸟来 2023-10-12 12:43 19阅读 0赞

实体类Student类代码如下所示：

package com.test.Test11;
    
    
    public class Student implements Comparable<Student>{
        private int age;
        private String name;
        private Double height;
    
        public int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Double getHeight() {
            return height;
        }
    
        public void setHeight(Double height) {
            this.height = height;
        }
    
        public Student(int age, String name, Double height) {
            this.age = age;
            this.name = name;
            this.height = height;
        }
    
        @Override
        public String toString() {
            return "Student{" +
                    "age=" + age +
                    ", name='" + name + '\'' +
                    ", height=" + height +
                    '}';
        }
    
        @Override
        public int compareTo(Student o) {
    
            /*
            //按照年龄排序
            return this.getAge()-o.getAge();*/
            //按照姓名排序
            return this.getName().compareTo(o.getName());
        }
    }
    
    测试类Test.java如下所示：

package com.test.Test11;
    
    import java.util.TreeMap;
    
    public class Test03 {
        public static void main(String[] args) {
            //TreeMap 唯一，有序(按升序或者降序排序)
            TreeMap<Student, Integer> map = new TreeMap<>();
    
            map.put(new Student(19,"blili",170.5), 1001);
            map.put(new Student(18,"blili",150.5), 1003);
            map.put(new Student(19,"alili",180.5), 1023);
            map.put(new Student(17,"clili",140.5), 1671);
            map.put(new Student(10,"dlili",160.5), 1891);
            System.out.println(map.size()); //4(上面的添加了5对数据，只出来4对数据)
            //按照age升序排列
            System.out.println(map);
            //按照年龄排序{Student{age=10, name='dlili', height=160.5}=1891, Student{age=17, name='clili', height=140.5}=1671, Student{age=18, name='blili', height=150.5}=1003, Student{age=19, name='blili', height=170.5}=1023}
            //按照姓名排序 {Student{age=19, name='alili', height=180.5}=1023, Student{age=19, name='blili', height=170.5}=1003, Student{age=17, name='clili', height=140.5}=1671, Student{age=10, name='dlili', height=160.5}=1891}
        }
    }