Java Math.pow() Rounding Error

Question

I\'m having trouble with (what I suspect is) a rounding error.

I have a string, 0.686357E-01, which I\'m trying to convert to a double. I\'ve been able to s

Answer 1

0.0686357 is not exactly representable as a double-precision value.

Two solutions:

• Use e.g. BigDecimal.
• Limit the displayed precision to a certain number of significant figures when converting back to human-readable.

Answer 2

Floating point numbers do not have perfect precision. If that is an issue, use BigDecimal:

String string = "0.686357E-01";
BigDecimal number = new BigDecimal(string);
System.out.println(number);

Answer 3

Double will print always like that, but the value will remain correct. You'll need to format the output to get the correct value. See DecimalFormat class.

Answer 4

You don't need to split it, Double.parseDouble can handle those kinds of numbers just fine.

double number = Double.parseDouble("0.686357E-01");

See? It works!