【Java每日一题】20161110

20161109问题解析请点击今日问题下方的“【Java每日一题】20161110”查看

package Nov2016;

import java.util.HashSet;

public class Ques1110 {
    public static void main(String[] args){
        String str1 = "123";
        String str2 = "123";
        String str3 = new String("123");
        String str4 = new String("123");

        HashSet<String> set = new HashSet<String>();
        set.add(str1);
        set.add(str2);
        set.add(str3);
        set.add(str4);

        System.out.println(set.size());
    }
}

今日问题：
请问主程序输出结果是什么？（点击以下“【Java每日一题】20161110”查看20161109问题解析）


题目原发布于公众号、简书：[url=http://mp.weixin.qq.com/s?__biz=MzI4ODEyMTgwMA==&mid=2650163243&idx=1&sn=527eae7a66d3ef59af75e4ff0ff71ab7&chksm=f3c1de8cc4b6579a600e5e76965ea80d49d020b3317ff40065042f72c5c9011a3884fc0f1a51#rd]【Java每日一题】20161110[/url]，[url=http://www.jianshu.com/p/fe2b96eb31e2]【Java每日一题】20161110[/url]
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[img]https://img-blog.youkuaiyun.com/20161017115128961?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/SouthEast[/img]