包装类型和非包装类型问题

package com.itstyle.mail.repository;

/***
 * @ClassName: Demo2
 * @Description:
 * @Auther: cxy
 * @Date: 2017/5/19:14:57
 * @version : V1.0
 */
public class Demo2 {
    public static void main(String[] args) {
        Long s=null;
        long s2 =0L;
        //long s3=null;
        Long s4=0L;
        System.out.println(s == s4);
    }
}