Remove trailing zeros from double

问题:

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?

回答1:

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

回答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));

回答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)

回答4:

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