①
详细见链接:
https://www.cnblogs.com/hq233/p/6539107.html
DecimalFormat format = newDecimalFormat(“00000”);
System.out.println(format.format(123)); //00123
②
详细见链接:
http://blog.sina.com.cn/s/blog_5ac88b350100auna.html
System. out.printf(“%05d”,12);//0001