Java每日一题20161026

20161025问题解析请点击今日问题下方的“【Java每日一题】20161026”查看（问题解析在公众号首发，公众号ID：weknow619）

package Oct2016;

import java.util.Date;

public class Ques1026 {   
    public static void main(String[] args) {      
        boolean b1 = "String" instanceof Object;//1      
        boolean b2 = new String() instanceof String;//2      
        boolean b3 = 'A' instanceof Character;//3      
        boolean b4 = null instanceof String;//4      
        boolean b5 = (String)null instanceof String;//5      
        boolean b6 = new Date() instanceof String;//6   
    }
}

今日问题：请问主程序哪些语句会有编译错误？（点击以下“【Java每日一题】20161026”查看20161025问题解析）