Print a Double as a String with unknown decimal length

Question

I need to print a Double as a String but I don't know how many decimal places there will be and I have to be prepared for as many as possible. Right, now I'm using this ugly solution:

Double dubs = 0.000157;

NumberFormat formatter = new DecimalFormat(
    "##.########################################################################################");
System.out.println(formatter.format(dubs));

Why do you even need to convert it to a string? Why not just print it? — Mureinik, Oct 09 '17 at 19:47
because it prints in scientific notation and that doesn't meet my requirements — ArcticDoom, Oct 09 '17 at 19:50
in double number, you need to precise the number of digit after the dot (.) — JHDev, Oct 09 '17 at 19:53

Steampunkery · Answer 1 · 2017-10-09T20:55:18.030

1

You can do this with no conversion:

public class codesnippets {

 public static void main(String[] args)
 {
     Double dubs = 0.000157;
     System.out.printf("%f", dubs);
 }

}

You can also use

Double dubs = 0.000157;
String dubs_format = String.format("%f", dubs);
System.out.println(dubs);

EDIT: Apparently there is a precision loss when using "%f" as a format string. If this is the case for you, use "%.10f"

edited Oct 09 '17 at 20:55

answered Oct 09 '17 at 19:52

Steampunkery

3,839
2
19
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since it is a double wouldn't it be %lf? – Tyler Oct 09 '17 at 19:53
@Tyler this is Java, not C – Steampunkery Oct 09 '17 at 19:55
Ok but to be clear I need an actual String object in order to place it in an XML document – ArcticDoom Oct 09 '17 at 19:56
Yes but I assumed Java would follow the same formats for printf, that's why I asked. Cheers – Tyler Oct 09 '17 at 19:57
This seems to work, extrapolated from your idea: String dubString= String.format("%f", dubs); System.out.println(dubString); – ArcticDoom Oct 09 '17 at 20:02
Nice. I’ll add it to the answer. – Steampunkery Oct 09 '17 at 20:03
1

@Steampunkery Can you advise, If Double dubs = 0.000157001; – Oct 09 '17 at 20:16
@SamDev it should be the same. What’s your problem? – Steampunkery Oct 09 '17 at 20:36

Sinil · Answer 2 · 2017-10-09T19:55:34.010

0

Try here man. I think this is what you're saying. The answer given at the bottom.

Number of decimal digits in a double

Here is what I meant.

double d= 234.12413;
String text = Double.toString(Math.abs(d));
int integerPlaces = text.indexOf('.');
int decimalPlaces = text.length() - integerPlaces - 1;

Then you just concatenate them

String xmlString = integerPlaces.toString() + "." + decimalPlaces.toString();

edited Oct 09 '17 at 19:55

answered Oct 09 '17 at 19:51

Sinil

87
10

Please don’t post link only answers. – Steampunkery Oct 09 '17 at 19:52
I can't comment yet. Should I repeat someone else's answer ? – Sinil Oct 09 '17 at 19:53
2

Flag the question as a duplicate. – azurefrog Oct 09 '17 at 19:54
Ok cool, I didn't realize that was an option yet. I see that I can now. Thanks guys. – Sinil Oct 09 '17 at 19:57

score 0 · Answer 3 · answered Oct 09 '17 at 20:03

0

This seemed to work based on Steampunkery's idea. The catch was that I needed an actual String which I realize I wasn't clear on.

String dubString= String.format("%f", dubs); 
System.out.println(dubString);

answered Oct 09 '17 at 20:03

ArcticDoom

64
6

Print a Double as a String with unknown decimal length

3 Answers3