What is the best way to separate double into two parts "integer & fraction" in java

java math double fractions
Eng.Fouad picture Eng.Fouad · May 19, 2011 · Viewed 9.8k times · Source

I have tried to separate 5.6 (for example) by the following method:

private static double[] method(double d)
{
    int integerPart = 0;
    double fractionPart = 0.0;
    integerPart = (int) d;
    fractionPart = d - integerPart;
    return new double[]{integerPart, fractionPart};
}

But what I got is:

[0] = 5.0
[1] = 0.5999999999999996

Do you have any suggestion about doing this without converting the number to string?

Answer

Bozho picture Bozho · May 19, 2011

Use BigDecimal to do that same calculation. (using doubles has precision problems because of its representation).

  • Construct it with new BigDecimal(String.valueOf(yourDouble)) (this is still going through string, but the parts are not separated via string manipulation)
  • use bd.subtract(new BigDecimal(bd.intValue()) to determine the fraction

Related questions

How to get the numbers after the decimal point? (java)

double d = 4.321562; Is there an easy way to extract the 0.321562 on it's own from d? I tried looking in the math class but no luck. If this can be done without converting to string or casting to anything else, even …

Read More
Calculating nth root in Java using power method

I was trying to get a cubic root in java using Math.pow(n, 1.0/3) but because it divides doubles, it doesn't return the exact answer. For example, with 125, this gives 4.9999999999. Is there a work-around for this? I know there is …

Read More
Math.random() explanation

This is a pretty simple Java (though probably applicable to all programming) question: Math.random() returns a number between zero and one. If I want to return an integer between zero and hundred, I would do: (int) Math.floor(Math.…

Read More