Question

I dont know how to handle new BigDecimal("0E30"). Its value is 0 but it doesn’t compare to BigDecimal.ZERO. See below:

System.out.println(new BigDecimal("0E30").add(BigDecimal.ONE));     // ---> 1
System.out.println(new BigDecimal("0E30").equals(BigDecimal.ZERO)); // ---> false

Could someone help me to make the comparison true (I know I can get a workaround by converting the BigDecimals to double, but I would like to know what is going on)?
I am using JRE 1.6.3.
thanks

Answer 1

From the docs (emphasis is mine):

Compares this BigDecimal with the specified Object for equality.
Unlike compareTo, this method considers two BigDecimals equal only if
they are equal in value and scale (thus 2.0 is not equal to 2.00 when
compared by this method).

In this case, the scale doesn’t match. So instead, you should use compareTo().

BigDecimal is one of the cases where equals() is inconsistent with compareTo():

Note: care should be exercised if BigDecimals are to be used as keys
in a SortedMap or elements in a SortedSet, as BigDecimal’s natural
ordering is inconsistent with equals. See Comparable, SortedMap or
SortedSet for more information.