How to format a 3-digit integer to a 4-digit string?

Question

I would like to format a 3-digit integer to a 4-digit string value. Example:

int a = 800;
String b = "0800";

Of course the formatting will be done at String b statement. Thanks guys!

Take a look at http://docs.oracle.com/javase/tutorial/java/data/numberformat.html — arynaq, Jul 17 '13 at 10:09

score 63 · Accepted Answer · edited Jul 17 '13 at 10:13

63

Use String#format:

String b = String.format("%04d", a);

For other formats refer the documentation

edited Jul 17 '13 at 10:13

AurA

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answered Jul 17 '13 at 10:10

Thilo

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Crap, almost 24hrs and I totally forgot to accept this answer! My bad! – Melvin Lai Jul 18 '13 at 09:46

score 5 · Answer 2 · edited Jul 17 '13 at 10:24

5

If you want to have it only once use String.format("%04d", number) - if you need it more often and want to centralize the pattern (e.g. config file) see the solution below.

Btw. there is an Oracle tutorial on number formatting.

To make it short:

import java.text.*;

public class Demo {

   static public void main(String[] args) {
      int value = 123;
      String pattern="0000";
      DecimalFormat myFormatter = new DecimalFormat(pattern);
      String output = myFormatter.format(value);
      System.out.println(output); // 0123
   }
}

Hope that helps. *Jost

edited Jul 17 '13 at 10:24

Ravi K Thapliyal

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answered Jul 17 '13 at 10:19

Jost

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This actually, might be somewhat better. – Melvin Lai Jul 18 '13 at 09:47

score 3 · Answer 3 · answered Jul 17 '13 at 10:12

3

Please try

String.format("%04d", b);

answered Jul 17 '13 at 10:12

wanana

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Beside `b` instead of `a`, how this answer differs from Thilo's answer? – Maroun Jul 17 '13 at 10:13
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@MarounMaroun: Well, look at the timestamps. Most likely just a race condition. – Thilo Jul 17 '13 at 10:14

score 2 · Answer 4 · answered Jul 17 '13 at 10:10

2

String b = "0" + a;

Could it be easier?

answered Jul 17 '13 at 10:10

JB Nizet

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@SandiipPatil That won't compile. – Aleks G Jul 17 '13 at 10:11
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Could it be easier? No. But maybe more robust/flexible. – Thilo Jul 17 '13 at 10:11
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@Thilo: agreed. But the question specifically asked for 3-digits integers. Why make things complex when they can be simple? Now, I also agree that your solution is far from being complex :-) – JB Nizet Jul 17 '13 at 10:13
Yeah sorry about that. It should be like this 'String b = "0"+ Integer.valueOf(a).toString();' – Sandiip Patil Jul 17 '13 at 10:14
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I think both our solutions may have trouble with negative numbers. Let's leave that as an exercise to the reader. – Thilo Jul 17 '13 at 10:15
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@SandiipPatil Euh... `"0" + a` works just fine... – assylias Jul 17 '13 at 10:15
Yeah simplest will be your solution but to intake any value Integer might work – Sandiip Patil Jul 17 '13 at 10:18
If negative you should do: `String b = "-0" + a * -1;` – Maroun Jul 17 '13 at 10:18

score 0 · Answer 5 · answered Jul 17 '13 at 10:20

0

You can always use Jodd Printf for that. In your case:

Printf.str("%04d", 800);

would do the job. This class was created before Sun added String.format and has somewhat more formatting options.

answered Jul 17 '13 at 10:20

igr

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How to format a 3-digit integer to a 4-digit string?

5 Answers5