list排序-白红宇

list排序

阅读量：2384 次

发布时间：2019-05-10

本文共 3720 字，大约阅读时间需要 12 分钟。

实现方式： 1 Collections.sort(List
      
        list, Comparator
        c); 2 list.sort(Comparator
        c) 3 stream实现 1和2是同一个；

1 list.sort(Comparator
       c)

userlist.sort(new ComparatorUser());

2 Collections.sort(List<T> list, Comparator<? super T> c);

Collections.sort(userlist, new ComparatorUser());

3 stream实现

userlist = userlist.stream()                .sorted((x, y) -> {                    int flag = x.getAge().compareTo(y.getAge());                    if (flag == 0) {                        return x.getName().compareTo(y.getName());                    } else {                        return flag;                    }                })                .collect(Collectors.toList());

全代码 测试类

import java.lang.reflect.Array;import java.util.ArrayList;import java.util.Arrays;import java.util.Collections;import java.util.List;import java.util.stream.Collectors;/** * ClassName: Test
 * Description: 
 * date: 2018/11/8 下午4:15
 * * @author chengluchao * @since JDK 1.8 */public class Test {    static List
       
         userlist = new ArrayList();    static {        userlist.add(new User("user001", "4"));        userlist.add(new User("user002", "1"));        userlist.add(new User("user003", "5"));        userlist.add(new User("user004", "2"));        userlist.add(new User("user005", "5"));        userlist.add(new User("user006", "3"));        userlist.add(new User("user007", "6"));    }    public static void main(String[] args) {        java7impl();        print();    }    /**     * 基于java7，6，5的实现     */    static void java7impl() {        userlist.sort(new ComparatorUser());    }    /**     * 基于java7，6，5的实现     */    static void java7impl2() {        Collections.sort(userlist, new ComparatorUser());    }    /**     * 基于java8的实现     * 不需要写ComparatorUser类     */    static void java8impl() {        Collections.sort(userlist, (x, y) -> {            int flag = x.getAge().compareTo(y.getAge());            if (flag == 0) {                return x.getName().compareTo(y.getName());            } else {                return flag;            }        });    }    /**     * 基于java8的实现     * stream实现，更为灵活     */    static void java8impl2() {        userlist = userlist.stream()                .sorted((x, y) -> {                    int flag = x.getAge().compareTo(y.getAge());                    if (flag == 0) {                        return x.getName().compareTo(y.getName());                    } else {                        return flag;                    }                })                .collect(Collectors.toList());    }    static void print() {        for (User user : userlist) {            System.out.println(user.getAge() + "," + user.getName());        }    }}

user类

/** * ClassName: User
 * Description: 
 * date: 2018/11/8 下午4:10
 * * @author chengluchao * @since JDK 1.8 */public class User {    String name;    String age;    public User(String name, String age) {        this.name = name;        this.age = age;    }    public String getAge() {        return age;    }    public void setAge(String age) {        this.age = age;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }}

import java.util.Comparator;public class ComparatorUser implements Comparator
       
         {    //比较的逻辑实现：：：//首先比较年龄，如果年龄相同，则比较名字    public int compare(User user0, User user1) {        int flag = user0.getAge().compareTo(user1.getAge());        if (flag == 0) {            return user0.getName().compareTo(user1.getName());        } else {            return flag;        }    }}

输出结果：

1,user002

2,user004

3,user006

4,user001

5,user003

5,user005

6,user007