JAVA如何实现利用固定的编码加两位数字自动生成编号？

下面两种方式都可以
NumberFormat format = NumberFormat.getInstance();
format.setMinimumIntegerDigits(6);
int i = 10;
String result = “xxxx” + format.format(i).replace(",", "")
System.out.println( result );

int i = 10;
String result = “xxxx” + String.format("%06d", i);
System.out.println(result);

static final String prefix = "xxxx";
static int i = 100;

public static String getNextID(){
i++;
String numStr = "" + i;
return prefix + numStr.substring(numStr.length - 2);
}