list排序

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

1 list.sort(Comparator<? super T> 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<br/>
 * Description: <br/>
 * date: 2018/11/8 下午4:15<br/>
 *
 * @author chengluchao
 * @since JDK 1.8
 */

public class Test {
    static List<User> 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<br/>
 * Description: <br/>
 * date: 2018/11/8 下午4:10<br/>
 *
 * @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<User> {

    //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