一个字符串根据固定规则添加下划线

1.正则实现：

 @Test
    public void Ce(){
        String org_id = "001001001001001001";
        String cc = "(.{3})";
        org_id = org_id.replaceAll (cc, "$1_");
        System.out.println (org_id);
    }

1： java实现：

 @Test
    public void Cc(){
        String bankCard = "001001001001001001";
        char[] bankArray = bankCard.toCharArray();
        String bankString = "";
        for(int i=0;i0){
                bankString +="_";
            }
            bankString += bankArray[i];
        }
        System.out.println (bankString);

    }

转自：https://blog.csdn.net/qq_36707431/article/details/78059542