Java8 Lamdba表达式经典例子

package com.company;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

/**
 * Lamdba表达式作为方法参数
 *
 * 需求：定义一个person类，带有姓名和年龄的属性，创建多个对象放进集合中，按照年龄升序排列
 */

class Person{
    private String name;
    private int age;

    public Person() {
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}
public class LamdbaDemo {
    public static void main(String[] args) {
        ArrayList<Person> list = new ArrayList<>();
        list.add(new Person("Kobe",38));
        list.add(new Person("james",36));
        list.add(new Person("Wade",39));
        System.out.println("按照年龄排序前：");
        for (Person p :list){
            System.out.println(p);
        }

        //传统的匿名内部类方式
//        Collections.sort(list, new Comparator<Person>() {
//            @Override
//            public int compare(Person o1, Person o2) {
//                return o1.getAge()-o2.getAge();
//            }
//        });

        Collections.sort(list,(Person o1, Person o2)->{ return o1.getAge()-o2.getAge();});

        System.out.println("按照年龄排序后：");
        for (Person p :list){
            System.out.println(p);
        }

    }
}

输出结果：

按照年龄排序前：
Person{name='Kobe', age=38}
Person{name='james', age=36}
Person{name='Wade', age=39}
按照年龄排序后：
Person{name='james', age=36}
Person{name='Kobe', age=38}
Person{name='Wade', age=39}