Remove trailing zeros from double

Question

I would like to remove all trailing zeros without truncating or rounding the number if it doesn't have any. For example, the number could be something like 12.0, in which case, the trailing zero should be removed. But the number could also be something almost irrational, like 12.9845927346958762... going on an on to the edge of the screen. Is there a way to setup DecimalFormat or some other class to cut of trailing zeros, while keeping the irrationality intact?

Mona

A double cannot represent an irrational value... – Phthalein

A DecimalFormat with 0.### will do such a thing. Of course double is just an approximation of floating point numbers. Maybe use BigDecimal, but that also is a final class. – Remove

@JoopEggen the zero before the decimal point would allow for more than the units place, such as something like 234123412.1? Sorry, I have never used DecimalFormat before. – Mona

Yes, and BTW a DecimalFormat does not modify the original value. – Remove

Possible duplicate of #703896 – Aureomycin

Answer 1

If you are willing to switch to BigDecimal, there is a #stripTrailingZeroes() method that accomplishes this.

Clothesbasket

Does that affect the resulting string representation? – Rillet

But wouldn't that put a number like 600.0 in scientific notation? – Mona

@Jesse Rusak: Yes. @Mohit: Not if you use #toPlainString() for output. – Clothesbasket

Answer 2

You can use String manipulation to remove trailing zeros.

private static String removeTrailingZeros(double d) {
  return String.valueOf(d).replaceAll("[0]*$", "").replaceAll(".$", "");
}

System.out.println(removeTrailingZeros(1234.23432400000));
System.out.println(removeTrailingZeros(12.0));

Evite

I think last "replace" should be more like: .replaceAll("\\.$", ""); – Wunder

Answer 3

private static String removeTrailingZeros(double d) {
return String.valueOf(d).replaceAll("[0]*$", "").replaceAll(".$", "");
}

or

private static String removeTrailingZeros(double d) {
return String.valueOf(d).replaceAll(".?0*$", "");
}

These are wrong code.

System.out.println(removeTrailingZeros(1234.23432400000));
return: 1234.23432
but must return: 1234.234324

---

private static String removeTrailingZeros(double myDouble) {
return (new BigDecimal(Double.toString(myDouble))).toPlainString().replaceAll("[0]
*$", "").replaceAll(".$", "");
}

This method is working wrong too

System.out.println(removeTrailingZeros(472.304000)); returns 472.30 instead of 472.304

System.out.println(removeTrailingZeros(472304000)); returns 47230 instead of 472304000

The #stripTrailingZeroes() or toPlainString() of the BigDecimal are good method, but nor alone.

//----------------BigDecimal.toPlainString-------------
System.out.println((new BigDecimal(Double.toString(4724))).toPlainString());
System.out.println((new BigDecimal(Double.toString(472304000))).toPlainString());

returns:
4724.0 (this is not fine - we don't want '.0')
472304000 (This is fine)

//----------------BigDecimal.stripTrailingZeros-------------
System.out.println((new BigDecimal(Double.toString(4724)).stripTrailingZeros()));
System.out.println((new BigDecimal(Double.toString(472304000d)).stripTrailingZeros()));

returns:
4724.0 (This is fine)
4.72304E+8 (This is not fine - we want 472304000)

The perfect resolution of the currect subject "Remove trailing zeros from double" is using
.stripTrailingZeros().toPlainString()

For example :
//---------BigDecimal.stripTrailingZeros.toPlainString-----------------
System.out.println(new BigDecimal(Double.toString(472.304000)).stripTrailingZeros().toPlainString());
System.out.println((new BigDecimal(Double.toString(4724)).stripTrailingZeros().toPlainString()));
System.out.println((new BigDecimal(Double.toString(472304000d)).stripTrailingZeros().toPlainString()));

Result is:
472.304 (correct)
4724 (correct)
472304000 (correct)

Bicentennial

Please edit the code blocks according to help document. In most cases, you don't actually need HTML tags. – Looper

Answer 4

double result = ...;
int intResult = (int)result;
if (result == intResult) {
    System.out.println(intResult);
} else {
    System.out.println(result);
}

Ancillary