Add leading zeroes to a string [duplicate]

Answer 1

A cheesy little trick

String str = "123";
String formatted = ("00000000" + str).substring(str.length())

If you started with a number instead:

Int number = 123;
String formatted = String.format("%08d", number);

Answer 2

public static void main(String[] args)
{
    String stringForTest = "123";
    int requiredLengthAfterPadding = 8;
    int inputStringLengh = stringForTest.length();
    int diff = requiredLengthAfterPadding - inputStringLengh;
    if (inputStringLengh < requiredLengthAfterPadding)
    {
        stringForTest = new String(new char[diff]).replace("\0", "0")+ stringForTest;
    }
    System.out.println(stringForTest);
}

Answer 3

Use String.format(), it has a specifier for that already:

String.format("%08d", myInteger);

More generally, see the javadoc for Formatter. It has a lot of neat stuff -- more than you can see at a first glance.

Answer 4

Why not make a simple padding function? I know there are libraries, but this is a very simple task.

System.out.println(padStr(123, "0", 8));
System.out.println(padStr(1234, "0", 8));
System.out.println(padStr(123456, "0", 8));
System.out.println(padStr(12345678, "0", 8));       

public String padStr(int val, String pad, int len) {
  String str = Integer.toString(val);
  while (str.length() < len)
    str = pad + str;
  return str;
}

Answer 5

Using DecimalFormat:

static public void main(String[] args) {
    int vals[] = {123, 1243, 123456, 12345678};
    DecimalFormat decimalFormat = new DecimalFormat("00000000");
    for (int val : vals) {
        System.out.println(decimalFormat.format(val));
    }
}

Output:

00000123
00001243
00123456
12345678

Answer 6

Using apache common langs lib:

StringUtils.leftPad(str, 8, '0');