public class StringFormatDemo {
    public static String format(int number){
        Date date=new Date();
        DateFormat df=new SimpleDateFormat("yyyyMMdd");
        String s1=df.format(date);
        NumberFormat nf=new DecimalFormat("0000");
        String s2=nf.format(number);

        return s1+s2;
    }

    public static void main(String[] args) {
        System.out.println(format(1));
    }
}

------解决方案--------------------
have a try
Java code
int id = 12;
String s = String.format("%tF%04d", new Date(), id).replaceAll("-", "");
System.out.println(s);

------解决方案--------------------

orcale
SQL code
select to_char(sysdate, 'YYYYMMDD') | to_char(id, '0000') from dual

------解决方案--------------------

select replace(to_char(sysdate, 'YYYYMMDD') || to_char(1, '0000'),' ','') from dual