Java DecimalFormat format function issue with large double number

Question

    String pattern = "0.00";
    double number = 999999999999999999999d;
    DecimalFormat decimalFormat = new DecimalFormat(pattern);
    decimalFormat.applyPattern(pattern);

    System.out.println(decimalFormat.format(number));

prints 1000000000000000000000.00

How can I print actual value.In this case I expect 999999999999999999999.00

A lot has been written on this... http://stackoverflow.com/questions/2100490/floating-point-inaccuracy-examples , http://stackoverflow.com/questions/5257166/java-floats-and-doubles-how-to-avoid-that-0-0-0-1-0-1-0-9000001 , http://stackoverflow.com/questions/5423545/sum-of-decimal-number-in-java — Danielson, Jul 07 '15 at 10:05
Possible duplicate: http://stackoverflow.com/questions/22028675/using-decimalformat-to-format-big-double-numbers — assylias, Jul 07 '15 at 10:12

score 0 · Answer 1 · answered Jul 07 '15 at 10:15

You can use BigDecimal to handle large number.

The BigDecimal class provides operations for arithmetic, scale manipulation, rounding, comparison, hashing, and format conversion. The toString() method provides a canonical representation of a BigDecimal.

score 0 · Answer 2 · answered Jul 07 '15 at 10:50

It's not a DecimalFormat issue - 999999999999999999999d really does equal 1000000000000000000000. If you want to store very large integers like this one, you should use the BigInteger class - a double only has enough precision to store about 15-16 significant figures accurately.

Java DecimalFormat format function issue with large double number

2 Answers2