Add leading zeroes to number in Java? [duplicate]

Solution 1:

String.format (https://docs.oracle.com/javase/1.5.0/docs/api/java/util/Formatter.html#syntax)

In your case it will be:

String formatted = String.format("%03d", num);

• 0 - to pad with zeros
• 3 - to set width to 3

Solution 2:

Since Java 1.5 you can use the String.format method. For example, to do the same thing as your example:

String format = String.format("%0%d", digits);
String result = String.format(format, num);
return result;

In this case, you're creating the format string using the width specified in digits, then applying it directly to the number. The format for this example is converted as follows:

%% --> %
0  --> 0
%d --> <value of digits>
d  --> d

So if digits is equal to 5, the format string becomes %05d which specifies an integer with a width of 5 printing leading zeroes. See the java docs for String.format for more information on the conversion specifiers.