rounding - Java BigDecimal: Round to the nearest whole value

Question

I need the following results

100.12 -> 100.00
100.44 -> 100.00
100.50 -> 101.00
100.75 -> 101.00

.round() or .setScale() ? How do I go about this?

Answer 1

You can use setScale() to reduce the number of fractional digits to zero. Assuming value holds the value to be rounded:

BigDecimal scaled = value.setScale(0, RoundingMode.HALF_UP);
System.out.println(value + " -> " + scaled);

Using round() is a bit more involved as it requires you to specify the number of digits to be retained. In your examples this would be 3, but this is not valid for all values:

BigDecimal rounded = value.round(new MathContext(3, RoundingMode.HALF_UP));
System.out.println(value + " -> " + rounded);

(Note that BigDecimal objects are immutable; both setScale and round will return a new object.)