Using variables within printf format section

Question

I've been working with the printf function for a bit now and was wondering if there was a way to use declared variables within the formatting section of printf? Something like:

int x = 5;

System.out.printf("%0xs\n", text);
// Normally this would be "%05s\n"

Meaning that I can use "x" as a changeable variable to be able to change how many 0 it can have. I am asking because I was given a code where the first line will give me a number, which is the amount of 0 I have to put before the text. Is something like this possible?

Does this answer your question? Can one initialize a Java string with a single repeated character to a specific length — Jesse
– Jesse, Commented Sep 13, 2022 at 19:48
System.out.printf("%0"+x+"d%s\n", 0, text) -- note 0 flag isn't allowed for %s, and even if it were it would be the total for the 0s and the text — dave_thompson_085
– dave_thompson_085, Commented Sep 13, 2022 at 22:01
Ty @dave_thompson_085! Sorry for the late reply but it really solved my issue. — Max Ringnalda
– Max Ringnalda, Commented Sep 17, 2022 at 1:43

Jake Henry · Accepted Answer · 2022-09-13 20:02:48Z

2

I don't think that you can do it in a singular String.format statement. However I was able to do with nested format.

final int padding = 5;
System.out.printf(String.format("%%0%dd%%n", padding), 7);
System.out.printf(String.format("%%%ds%%n", padding), "hey");

Output:

00007
  hey

Also, you can use %n to insert an end line character automatically.

answered Sep 13, 2022 at 20:02

Jake Henry

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2 Comments

dave_thompson_085 Over a year ago

%n is either LF or CRLF depending on platform; this may actually be better, or worse, but it is not the same as just \n.

Jake Henry Over a year ago

Correct. I figured I would mention it since OP is simply printing to the console.

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