Null Safe Compare two bigdecimal objects having 0.0 and 0

Question

Initially code was :

            if(!Objects.equals(src.getApplicationItemCost(), dest.getApplicationItemCost())){
               log.info("Difference")
            }

Output:

      getApplicationItemCost: src:0.0| dest:0
      Difference

ApplicationItemCost is of type BigDecimal.

If I use compareTo then I have to explicitly check nulls like :

LOG.info("getApplicationItemCost: src:" + src.getApplicationItemCost() + "| dest:" + dest.getApplicationItemCost());
        if((src.getApplicationItemCost()==null && dest.getApplicationItemCost()!=null)
                || (src.getApplicationItemCost()!=null && dest.getApplicationItemCost()==null)
                || !Objects.equals(src.getApplicationItemCost(), dest.getApplicationItemCost())
                || src.getApplicationItemCost().compareTo(dest.getApplicationItemCost())!=0 )

Any suggestion to compare 0.0 and 0. Why is this difference? (May be database has Number field and when converted to big decimal it does not show 0.0?)

Answer 1

Build a comparator:

Comparator<BigDecimal> c = Comparator.nullsFirst(Comparator.naturalOrder());

(Or nullsLast, it doesn't matter if you're only ever comparing to zero).

Then:

if (c.compare(first, second) != 0) {
  // ...
}

Answer 2

Try using

CompareToBuilder

class provided by

org.apache.commons.lang3

as it make null safe comparison. Sample code is:

public static <T, U> int nullSafeComparison(T t, U u) {
        return new CompareToBuilder().append(t, u).toComparison();
    }

public static void main(String[] args) {
        BigDecimal zero = BigDecimal.ZERO;
        BigDecimal zeroPzero = new BigDecimal("0.0");

        System.out.println( zero + " " + zeroPzero);

        System.out.println(nullSafeComparison(zero, zeroPzero));
    }

If both numbers are same it will return 0, if 1st is greater than 2nd the result will be 1 and -1 if 1st number is less than 2nd.

Answer 3

Custom BigDecimal null safe Comparison (without any exteranal library):

{
    BigDecimal big1, big2; 

    big1 = new BigDecimal(0); 
    big2 = new BigDecimal(0.0); 

    int compareResult1 = compareTo(b1,null);
    int compareResult2 = compareTo(null,b2);
}

public static <T extends Comparable<T>> int compareTo(final T c1, final T c2) {
    final boolean f1, f2;
    return (f1 = c1 == null) ^ (f2 = c2 == null) ? f1 ? -1 : 1 : f1 && f2 ? 0 : c1.compareTo(c2);
}