Format an Integer using Java String Format

Question

I am wondering if it is possible, using the String.format method in Java, to give an integer preceding zeros?

For example:

1 would become 001
2 would become 002
...
11 would become 011
12 would become 012
...
526 would remain as 526
...etc

At the moment I have tried the following code:

String imageName = "_%3d" + "_%s";

for( int i = 0; i < 1000; i++ ){
    System.out.println( String.format( imageName, i, "foo" ) );
}

Unfortunately, this precedes the number with 3 empty spaces. Is it possible to precede the number with zeros instead?

possible duplicate of Add leading zeroes in Java

Jonathon Faust
– Jonathon Faust

2011-05-17 17:13:53 +00:00
Commented May 17, 2011 at 17:13 — Jonathon Faust
– Jonathon Faust, Commented May 17, 2011 at 17:13

Basil Bourque · Accepted Answer · 2019-09-15 18:19:05Z

247

String.format("%03d", 1)  // => "001"
//              │││   └── print the number one
//              ││└────── ... as a decimal integer
//              │└─────── ... minimum of 3 characters wide
//              └──────── ... pad with zeroes instead of spaces

See java.util.Formatter for more information.

edited Sep 15, 2019 at 18:19

Basil Bourque

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answered May 17, 2011 at 17:16

maerics

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Comments

Mat · Accepted Answer · 2011-05-17 17:13:37Z

183

Use %03d in the format specifier for the integer. The 0 means that the number will be zero-filled if it is less than three (in this case) digits.

See the Formatter docs for other modifiers.

answered May 17, 2011 at 17:13

Mat

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Comments

Anil Bharadia · Accepted Answer · 2017-08-01 06:40:58Z

13

If you are using a third party library called apache commons-lang, the following solution can be useful:

Use StringUtils class of apache commons-lang :

int i = 5;
StringUtils.leftPad(String.valueOf(i), 3, "0"); // --> "005"

As StringUtils.leftPad() is faster than String.format()

edited Aug 1, 2017 at 6:40

answered Jul 9, 2013 at 11:30

Anil Bharadia

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2 Comments

My Head Hurts Over a year ago

StringUtils.leftPad is another good choice and could be argued that it is more readable plus it allows you to pad with other characters. I have had a Google around but I cannot find anything that confirms it is faster - could you provide some evidence for that?

Anil Bharadia Over a year ago

github.com/anilbharadia/JavaPerformanceTests/blob/master/… Run it with junit and check the time

Munawar Abbas · Accepted Answer · 2022-07-22 02:53:50Z

0

Instead of using String.format(**). it's good if you use DecimalFormat java API which builds for this type of purposes.Let me explain with code

    String pattern = "000";
   double value = 12; //can be 536 or any 
   DecimalFormat formatter = new DecimalFormat(pattern);
   String formattedNumber = formatter.format(value);
   System.out.println("Number:" + value + ", Pattern:" +
                pattern + ", Formatted Number:" +
                formattedNumber);

answered Jul 22, 2022 at 2:53

Munawar Abbas

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1 Comment

Lubo Over a year ago

Why do you think so?

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