What I want to do is getting the first 2 digits of a number. If number hasn't digits more than 1 then It will add leading zeros.
s variable equals to "122" but I want to get first 2 digits which are "12". I think there is a problem with my format.
for example if totalNumberOfCars equals 6 then s variable will equals to "06".
int totalNumberOfCars = 122;
String s = String.format("%02d", (totalNumberOfCars + 1))
EDIT: Is there anyone knows what String.format("%02d", totalNumberOfCars) does?
I'm afraid that String.format() won't do the job, see http://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html#syntax.
But your format string will be a good starting point for a substring since any ifs are unnecessary:
int totalNumberOfCars = 122;
String s = String.format("%02d", (totalNumberOfCars + 1));
s = s.substring(0,2);
By the way the condensed explaination from the javadoc link above:
The format specifiers which do not correspond to arguments have the following syntax:
%[flags][width]conversion
[...] further down on the same page:
Flags '0' [...] [means] zero-padded
[...] further down on the same page:
Width
The width is the minimum number of characters to be written to the output. For the line separator conversion, width is not applicable; if it is provided, an exception will be thrown.
Example output would be:
1 --> 01
-1 --> -1
10 --> 10
122--> 122
Maybe not very elegant, but it should work:
String s = ((totalNumberOfCars<10?"0":"")+totalNumberOfCars).substring(0,2);
String s = substring_safe (s, 0, 2);
static String substring_safe (String s, int start, int len) { ... } which will check lengths beforehand and act accordingly (either return smaller string or pad with spaces).
