CODEWITHSUNDEEP
javabigdecimal
HyongMinLee
HyongMinLee

Reputation: 21

How to truncate/round large BigDecimal numbers to be in scientific notation

I am making a calculator in Java where I can only display up to 17 characters so . is considered as a character and E15 is considered 3 characters.

I have researched extensively on this site but could not a find a question like this... (sorry if there is a duplicate)

How can I force say a large BigDecimal like 9999998990000001 to something like 9.999998990000E15.

I do not want it to be in scientific always so numbers say less than 16 characters long should not be in scientific notation.

Essentially like a handheld calculator if you are having trouble understanding.

Upvotes: 2

Views: 214

Answers (1)

ZetaPR
ZetaPR

Reputation: 993

You could simply check if the numbers is less than 16 characters if not just do:

private static String formatNumber(BigDecimal bDecimal, int scaleInt) {
  NumberFormat nFromatter = new DecimalFormat("0.0E0");
  nFromatter.setRoundingMode(RoundingMode.HALF_UP);
  nFromatter.setMinimumFractionDigits(scaleInt);
  return formatter.format(bDecimal);
}

System.out.println(formatNumber(new BigDecimal("0.00001"), 2)); 
// Output will be 1.00E-5
System.out.println(formatNumber(new BigDecimal("0.00001"), 3)); 
// Output will be 1.000E-5

Upvotes: 2

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