JDK8-lambda表达式四种forEach性能对比

jdk8新特性流Stream编程

看了网上一些性能的比较，这里自己写一个进行测试

对比以下四种 

普通forEach、java8中新的forEach、stream+forEach、parallelStream+forEach

package com.huajie.Lambda;

import lombok.extern.slf4j.Slf4j;
import org.junit.Before;
import org.junit.Test;

import java.util.ArrayList;
import java.util.List;

@Slf4j
public class Mode2 {

    List listUser = new ArrayList<>();

    @Before
    public void initList() {
        listUser = this.getListUsers();
    }

    @Test
    public void test() {
        //一般forEach
        long startSimpleTime = System.currentTimeMillis();
        for (User user : listUser) {
            user.toString();
        }
        long endSimpleTime = System.currentTimeMillis();
        System.out.println("Simple:" + (endSimpleTime - startSimpleTime));

        //java8中新的forEach
        long startLambda = System.currentTimeMillis();
        listUser.forEach(User::toString);
        long endLambda = System.currentTimeMillis();
        System.out.println("Lambda:" + (endLambda - startLambda));

        //java8中新的stream+forEach
        long startStream = System.currentTimeMillis();
        listUser.stream().forEach(User::toString);
        long endStream = System.currentTimeMillis();
        System.out.println("Stream:" + (endStream - startStream));

        //java8中新的parallelStream+forEach
        long startParallelStream = System.currentTimeMillis();
        listUser.parallelStream().forEach(User::toString);
        long endParallelStream = System.currentTimeMillis();
        System.out.println("ParallelStream:" + (endParallelStream - startParallelStream));
    }


    private List getListUsers() {
        List listUser = new ArrayList();
        for (int i = 0; i < 10000000; i++) {
            listUser.add(new User("user" + i, i));
        }
        return listUser;
    }


}

package com.huajie.Lambda;

import lombok.Data;

@Data
public class User {
    private String name;
    private Integer age;

    public User(String name, Integer age) {
        this.name = name;
        this.age = age;
    }
}

1000W条数据

100W条数据

10W条数据

1W条数据

1000条数据

java8中新加入的forEach和普通的forEach临界值大概在150W条

由以上测试能得到的结果：

150W条数据以下and10W以上：lambda>simple>stream>paralleStream

150W条数据以上：simple>lambda>stream>paralleStream

从性能上考虑：小数据量用普通的forEach就可以，没有必要使用java8中的新出来的几种，已经在项目中使用的也不需要改回来，10W条也就几毫秒的差距