Java String Format: "%0" and "d%s"

Question

I would like to know what is the meaning of "%0" and "d%s" in java when formatting a string.

String.format("%0"+ (8 - "Apple".length() )+"d%s",0 ,"Apple");

Output:

000Apple

I was searching for a way to format a string with leading zeros, and that code does the work, but I don't know why it works.

you might have problems for strings larger than 8 chars – Kevin Seifert Aug 14 '15 at 17:28 — Kevin Seifert, Aug 14 '15 at 17:28

score 12 · Accepted Answer · answered Aug 14 '15 at 17:26

%d means number. %0nd means zero-padded number with a length.

You build n by subtraction in your example.

%s is a string.

Your format string ends up being this:

"%03d%s", 0, "Apple"

So you print a zero-padded 0 that's three digits long, and the string "Apple".

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