What is the alternate method for string.format method

[Robert Jack]

Hi.

  I am using string.format method which is used to add zero's.

  I set the roll number value is: 8123 and number of digits i used 8. This string.format method will return the value is 00008123.

  What is the alternate method for string.format

   String.format("%0" + 8 + "d", 8123l) --> 00008123

public class MyCode {

	private long rollNumber;

	public static void main(String args[]) {

		MyCode myCode = new MyCode();
		myCode.rollNumber = 8123;
		String str = myCode.getFormatedRollNumber(8);
		System.out.println("str: " + str);
	}

	public String getFormatedRollNumber(int totalDigits) {
		return String.format("%0" + totalDigits + "d", rollNumber);
	}
}

Thanks in advance.

[Robert Jack]

return String.format("%0" + totalDigits + "d", rollNumber);

Sonar qube tool saying the critical error
"Format specifiers should be used instead of string concatenation"

But i am getting the perfect result.

Please help me this.

[Campbell Ritchie]

I presume you mean alternative. I think you are right to say your method works, but it can be improved, so I don't think an alternative is necessary.
That second method of yours (lines 13‑15) behaves rather like a function and shou‍ld probably be marked static final. In that case you must also pass the number to be formatted as an argument. If the number is a long, always append the final L: 8123L. Don't use l because I can see the earlier number as 81231. You now have this sort of method

/**
 * ...
 *@throws IllegalArgumentException if incorrect length for the output is passed
 */
public static final String formatIntNCharacters(long number, int howManyCharacters)
{
   if (howManyCharacters < 1 || howManyCharacters > 80)
   {
       throw new IllegalArgumentException("Number of characters must be positive up to 80");
   }
   return String.format("%0" + howManyCharacters + "d", number);
}

As for the warning from the IDE etc. There comes a time when you have to bite the bullet and tell the IDE you do know what you are doing and I am going to ignore that warning
I you write yourself a utility class, you can put that method in the utility class and keep it for ever.