格式

        (o1, o2) -> {
            return o1.* > o2.* ? 0 : -1;
        }

等同于

       new Comparator<Student>() {
            @Override
            public int compare(o1,  o2) {
                return o1.* > o2.* ? 0 : 1;
            }
        }

示例

顺序取决于返回值

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

/**
 * @author rui
 * @create 2020-06-28 17:38
 */
public class Mar {

    public static void main(String[] args) {
        List<Student> msgList = new ArrayList<>();
        msgList.add(new Student(12, "小明"));
        msgList.add(new Student(10, "小弘"));
        msgList.add(new Student(14, "小大"));
        msgList.add(new Student(9, "小是"));
        msgList.sort((o1, o2) -> {
            return o1.getAge() > o2.getAge() ? 0 : -1;
        });
        for (Student student : msgList
        ) {
            System.out.println(student);
        }
        msgList.sort(new Comparator<Student>() {
            @Override
            public int compare(Student o1, Student o2) {
                return o1.getAge() > o2.getAge() ? 0 : 1;
            }
        });
        System.out.println("***********************");
        for (Student student : msgList
        ) {
            System.out.println(student);
        }
    }
}

class Student {
    private int age;
    private String name;

    public Student(int age, String name) {
        this.age = age;
        this.name = name;
    }

    @Override
    public String toString() {
        return "Student{" +
                "age=" + age +
                ", name=‘" + name + ‘\‘‘ +
                ‘}‘;
    }

    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;
    }
}

lamdba表达式做比较