List集合根据存储对象的属性字段排序实现

1. List集合根据存储对象的属性字段排序实现

package com.huixin;import java.util.ArrayList;import java.util.Collections;import java.util.List;/** * ListSort类 * * @author Lance * @date 2017/03/10 */public class ListSort {    public static void main(String[] args) {        List<Student> students = new ArrayList<Student>();        students.add(new Student("张三", 24));        students.add(new Student("李四", 23));        students.add(new Student("王五", 25));        System.out.println("before sort:");        for (Student bean : students) {            System.out.println("before sort---->age: " + bean.getAge());        }        Collections.sort(students);        System.out.println("after sort:");        for (Student bean : students) {            System.out.println("after sort---->age: " + bean.getAge());        }    }}class Student implements Comparable<Student> {    private String name;    private Integer age;    public Student(String name, Integer age) {        this.name = name;        this.age = age;    }    /*     * s的age小于this的对应字段，则返回负数；     * 大于则返回正数；     * 建议去了解compareTo背后的真相     */    @Override    public int compareTo(Student s) {        return s.getAge().compareTo(this.getAge());    }    public Integer getAge() {        return age;    }    public void setAge(Integer age) {        this.age = age;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }}

1. 预期结果

Connected to the target VM, address: '127.0.0.1:3850', transport: 'socket'before sort:before sort---->age: 24before sort---->age: 23before sort---->age: 25after sort:after sort---->age: 25after sort---->age: 24after sort---->age: 23

======================================================
以上是java8之前的用法，java8提供了多种操作方式。博文修改2017.4.7

• 实体类

@AllArgsConstructor@NoArgsConstructor@Dataclass Teacher {    private String name;    private Integer age;}

• 使用Lambda表达式

 List<Teacher> teachers = new ArrayList<Teacher>();        teachers.add(new Teacher("张三", 24));        teachers.add(new Teacher("李四", 23));        teachers.add(new Teacher("王五", 25));        System.out.println("before sort:");        for (Teacher bean : teachers) {            System.out.println("before sort---->age: " + bean.getAge());        }        //Lambda        teachers.sort((s1, s2) -> s1.getAge().compareTo(s2.getAge()));        System.out.println("after sort:");        for (Teacher bean : teachers) {            System.out.println("after sort---->age: " + bean.getAge());        }

• 使用Comparator操作器

//Comparator        Collections.sort(teachers, Comparator.comparing(Teacher::getAge));

• 反序排列

Comparator<Teacher> comparator = (t1, t2) -> t1.getAge().compareTo(t2.getAge());        teachers.sort(comparator.reversed());

• 组合排序

//组合排序        teachers.sort(Comparator.comparing(Teacher::getAge).thenComparing(Teacher::getName));

• 完整示例代码

package com.huixin.utils.common;import lombok.AllArgsConstructor;import lombok.Data;import lombok.NoArgsConstructor;import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.List;/** * ListSort类 * * @author Lance * @date 2017/03/10 */public class ListSortJava8 {    public static void main(String[] args) {        List<Teacher> teachers = new ArrayList<Teacher>();        teachers.add(new Teacher("张三", 24));        teachers.add(new Teacher("李四", 23));        teachers.add(new Teacher("王五", 25));        teachers.add(new Teacher("钱二", 23));        System.out.println("before sort:");        for (Teacher bean : teachers) {            System.out.println("before sort---->age: " + bean.getAge() + "==name：" + bean.getName());        }        //Lambda//        teachers.sort((t1, t2) -> s1.getAge().compareTo(s2.getAge()));        //Comparator//        Collections.sort(teachers, Comparator.comparing(Teacher::getAge));        //reversed//        Comparator<Teacher> comparator = (t1, t2) -> t1.getAge().compareTo(t2.getAge());//        teachers.sort(comparator.reversed());        //组合排序        teachers.sort(Comparator.comparing(Teacher::getAge).thenComparing(Teacher::getName));        System.out.println("after sort:");        for (Teacher bean : teachers) {            System.out.println("after sort---->age: " + bean.getAge() + "==name：" + bean.getName());        }    }}@AllArgsConstructor@NoArgsConstructor@Dataclass Teacher {    private String name;    private Integer age;}