Truncate double numbers to two decimal places using DecimalFormat: Usage of API documented as @since 1.6+ error

Question

I'm trying to use this code to get number 2.90 printed from the intial number 2.90689:

double number = 2.90689;
DecimalFormat df = new DecimalFormat("#.##");
df.setRoundingMode(RoundingMode.FLOOR);  //error
System.out.println(df.format(number));

However I get the Usage of API documented as @since 1.6+ error when trying to set rounding mode. How do I solve this in a modern way? All answers I've found use this seemingly deprecated code.

PS: It's not an error, but a warning in IDE. When run, it also doesn't work properly: prints 2.9 instead of 2.90. I've made this repl: https://repl.it/repls/IllInterestingComputers.

Screenshot of the warning:

Maybe this helps: https://stackoverflow.com/questions/38551978/usage-of-api-documented-as-since1-6/40732834 — Jens, Jan 16 '20 at 18:55
But it has been marked @since for a reason? Is there no non-deprecated way to truncate doubles? — parsecer, Jan 16 '20 at 18:56
It is marked so you know that is not available in Java 1.5 or less. It is not marked as deprected, which you should solve — Jens, Jan 16 '20 at 18:57

score 3 · Accepted Answer · answered Jan 16 '20 at 19:03

3

double number = 2.90689;
DecimalFormat df = new DecimalFormat("#.00");
df.setRoundingMode(RoundingMode.FLOOR);  //error
System.out.println(df.format(number));

Please check https://docs.oracle.com/javase/7/docs/api/java/text/DecimalFormat.html

0   Number  Yes Digit
#   Number  Yes Digit, zero shows as absent

answered Jan 16 '20 at 19:03

dassum

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So I should just - ignore the warning? – parsecer Jan 16 '20 at 19:13
I didn't even get the warning in IntelliJ java 8. – dassum Jan 16 '20 at 19:14
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The question is how to suppress the warning.Why you answer with code that shows the same warning/information? – Jens Jan 16 '20 at 19:17
@Jens No, it also turned out the code I had didn't print `2.90`, but rather `2.9` (see PS). – parsecer Jan 16 '20 at 19:18
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I asked @parsecer do you want 2.90689 to be displayed as 2.90? and he replied yes to it . So i posted the answer – dassum Jan 16 '20 at 19:18
@dassum I attached a screenshot of the warning – parsecer Jan 16 '20 at 19:18
@dassum Turned out I asked language level 5 after all. I thought it was 8, because it was 8 for the project, but not the module (in Idea Intellij) – parsecer Jan 16 '20 at 19:22
@parsecer that it is a different question as the first one and should asked as a new question – Jens Jan 16 '20 at 19:22

score 0 · Answer 2 · answered Jan 16 '20 at 19:19

0

You should use BigDecimal, heres an example:

double number = 2.90689;
BigDecimal roundedDown = BigDecimal.valueOf(number).setScale(2, RoundingMode.DOWN);
System.out.println("Original: " + number);
System.out.println("Rounded: " + roundedDown);

Stdout:

Original: 2.90689
Rounded: 2.90

answered Jan 16 '20 at 19:19

J11

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Why OP *should use* BigDecimal. The number is not to big for a double – Jens Jan 16 '20 at 19:24
@Jens Loss of precision, added link to answer – J11 Jan 16 '20 at 19:29

Truncate double numbers to two decimal places using DecimalFormat: Usage of API documented as @since 1.6+ error

2 Answers2