Null safe Comparator for BigDecimal-CodePudding

I want to have an null safe Comparator. But I tried many ways ii doesn't work. **getBenefitLimit **is an **BigDecimal **value there no comparing BigDecimal values in Comparator. In that case how can figure this...

My code and error Using with out null (Comparator.nullsFirst)

List<ProductBenefitResponse> list = new ArrayList<>(benefitMap.values());
list.sort(Comparator.comparing(ProductBenefitResponse::getDescription).thenComparing(ProductBenefitResponse::getBenefitLimit));

Error must be :-

java.lang.NullPointerException: null
    at java.base/java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:469)
    at java.base/java.util.Comparator.lambda$thenComparing$36697e65$1(Comparator.java:217)
    at java.base/java.util.TimSort.binarySort(TimSort.java:296)
    at java.base/java.util.TimSort.sort(TimSort.java:239)
    at java.base/java.util.Arrays.sort(Arrays.java:1515)
    at java.base/java.util.ArrayList.sort(ArrayList.java:1750)

My code and error Using with null (Comparator.nullsFirst)

List<ProductBenefitResponse> list = new ArrayList<>(benefitMap.values());
list.sort(Comparator.nullsFirst(
        Comparator.comparing(ProductBenefitResponse::getBenefitLimit)
                .thenComparing(ProductBenefitResponse::getDescription)
));

Error must be :-

java.lang.NullPointerException: null
    at java.base/java.math.BigDecimal.compareTo(BigDecimal.java:3065)
    at java.base/java.math.BigDecimal.compareTo(BigDecimal.java:228)
    at java.base/java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:469)
    at java.base/java.util.Comparator.lambda$thenComparing$36697e65$1(Comparator.java:216)
    at java.base/java.util.Comparators$NullComparator.compare(Comparators.java:83)
    at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
    at java.base/java.util.TimSort.sort(TimSort.java:234)
    at java.base/java.util.Arrays.sort(Arrays.java:1515)
    at java.base/java.util.ArrayList.sort(ArrayList.java:1750)

What is wrong in this code and please give me and answer...

CodePudding user response：

Right now the nullsFirst is applied to the ProductBenefitResponse objects, not the BigDecimal values.

Try this:

Comparator<BigDecimal> bigDecimalComparator = Comparator.nullsFirst(Comparator.naturalOrder());
list.sort(
    Comparator
        .comparing(ProductBenefitResponse::getDescription)
        .thenComparing(ProductBenefitResponse::getBenefitLimit, bigDecimalComparator)
);

By specifying the null-safe comparator for the mapping, it applies to the result of the mapping.

CodePudding user response：

I Found Easy way to Do that Is this correct ? It return the value I want anyway.

List<ProductBenefitResponse> list = new ArrayList<>
(benefitMap.values());list.sort(Comparator.comparing(ProductBenefitResponse::getDescription,Comparator.nullsLast(Comparator.naturalOrder()))
                    .thenComparing(ProductBenefitResponse::getBenefitLimit,Comparator.nullsLast(Comparator.naturalOrder())));