Java List sort() 排序

sort是java.util.List接口的默认方法。

List的排序方法在Java 8中被引入。

排序方法接受比较器作为参数，并根据指定的比较器对这个列表进行排序。

 default void sort(Comparator<? super E> c)

示例代码：

import java.text.Collator;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.Locale;public class ListSort {private static Student zs = new Student("张三", 38, "156****6549");private static Student ls = new Student("李四", 28, "138****4267");private static Student ww = new Student("王五", 20, "186****7391");private static Student zs2 = new Student("张三", 26, "172****6549");private static Student ww2 = new Student("王五", null, "196****7391");public static void main(String[] args) {List<Student> studentList = Arrays.asList(zs, ls, ww, zs2, ww2);Collator collator = Collator.getInstance(Locale.CHINA);// 按照姓名排序Comparator<Student> nameComparator = Comparator.comparing(Student::getName, collator);// 正序studentList.sort(nameComparator);// 倒序studentList.sort(nameComparator.reversed());System.out.println("************姓名****************");studentList.forEach(System.out::println);// 年龄排序(空值最前)studentList.sort(Comparator.comparing(Student::getAge, Comparator.nullsFirst(Integer::compareTo)));System.out.println("************年龄****************");studentList.forEach(System.out::println);// 手机号前三位排序studentList.sort(Comparator.comparing(student -> student.getPhoneNum().substring(0, 3)));System.out.println("************手机号****************");studentList.forEach(System.out::println);// 多字段排序(按姓名，再按年龄)studentList.sort(Comparator.comparing(Student::getName, collator).thenComparing(Student::getAge, Comparator.nullsLast(Comparator.naturalOrder())));System.out.println("************多字段****************");studentList.forEach(System.out::println);}public static class Student {/*** 姓名*/private String name;/*** 年龄*/private Integer age;/*** 手机号*/private String phoneNum;public Student(String name, Integer age, String phoneNum) {this.name = name;this.age = age;this.phoneNum = phoneNum;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public String getPhoneNum() {return phoneNum;}public void setPhoneNum(String phoneNum) {this.phoneNum = phoneNum;}@Overridepublic String toString() {return "Student{" +"name='" + name + '\'' +", age=" + age +", phoneNum='" + phoneNum + '\'' +'}';}}}

排序结果：

************姓名****************
Student{name='张三', age=38, phoneNum='156****6549'}
Student{name='张三', age=26, phoneNum='172****6549'}
Student{name='王五', age=20, phoneNum='186****7391'}
Student{name='王五', age=null, phoneNum='196****7391'}
Student{name='李四', age=28, phoneNum='138****4267'}
************年龄****************
Student{name='王五', age=null, phoneNum='196****7391'}
Student{name='王五', age=20, phoneNum='186****7391'}
Student{name='张三', age=26, phoneNum='172****6549'}
Student{name='李四', age=28, phoneNum='138****4267'}
Student{name='张三', age=38, phoneNum='156****6549'}
************手机号****************
Student{name='李四', age=28, phoneNum='138****4267'}
Student{name='张三', age=38, phoneNum='156****6549'}
Student{name='张三', age=26, phoneNum='172****6549'}
Student{name='王五', age=20, phoneNum='186****7391'}
Student{name='王五', age=null, phoneNum='196****7391'}
************多字段****************
Student{name='李四', age=28, phoneNum='138****4267'}
Student{name='王五', age=20, phoneNum='186****7391'}
Student{name='王五', age=null, phoneNum='196****7391'}
Student{name='张三', age=26, phoneNum='172****6549'}
Student{name='张三', age=38, phoneNum='156****6549'}