How to format a float number in java String.ValueOf

Question

I have this code:

StringBuilder sbp = new StringBuilder().append(
   String.valueOf((temp / 10F)))
   .append(" \260C / ").append(String.valueOf((temp/10F)*9/5+32))
   .append(" \260F");

and I get this result:

 29.8 C / 85.641 F

I want to format the float numbers to show max 1 digit after decimals, 85.6 instead of 85.641

I think this is a duplicate http://stackoverflow.com/questions/703396/how-to-nicely-format-floating-numbers-to-string-without-unnecessary-decimal-0 — bhspencer, Jan 23 '15 at 22:52
not really, because I needed the format for StringBuilder, but it seems that I still need to make a String.format first and then append to StringBuilder — Mario, Jan 23 '15 at 23:00

score 4 · Accepted Answer · answered Jan 23 '15 at 22:53

4

You could achieve this using String.format instead:

String s = String.format("%.1f C / %.1f F", temp / 10F, (temp/10F)*9/5+32);

answered Jan 23 '15 at 22:53

Alan

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Thanks !, now I can append the s to stringbuilder – Mario Jan 23 '15 at 23:04

score 1 · Answer 2 · answered Jan 23 '15 at 22:55

1

Here's a simple example that you can implement in your StringBuilder:

float num = 85.641f;
num = Math.round(num * 10) / 10f; // pi is now 85.6

answered Jan 23 '15 at 22:55

Malik Brahimi

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How about this, Mario? What do you think Alan? – Malik Brahimi Jan 23 '15 at 22:59
All you have to do is cast to a string with `String.valueOf(num)`. – Malik Brahimi Jan 23 '15 at 23:00
I need to do this with each number, which makes the code redundant, the answer from Alan is much more compact. – Mario Jan 23 '15 at 23:03

How to format a float number in java String.ValueOf

2 Answers2