Summing a List of BigIntegers using streams in Java

Asked Apr 25 '18 at 13:05

Active Apr 26 '18 at 21:22

Viewed 2,250 times

I have a List<BigInteger> and I want to sum its contents. It can be easily done by looping through it.

 List<BigInteger> listOfNumbers = new ArrayList<>();
  //Some code that populates listOfNumbers
  ... 
  BigInteger sum = new BigInteger("0");
  for(BigInteger num : listOfNumbers) {
        sum = sum.add(num);
  }

I was wondering if it was possible to do it using Java 8 streams.

edited Apr 26 '18 at 21:22

Stefan Zobel

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asked Apr 25 '18 at 13:05

bisarch

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you could try something like listOfNumbers.stream().map(BigDecimal::doubleValue).sum().map(BigDecimal:valueOf), but your solution is more optimal – Borislav Stoilov Apr 25 '18 at 13:07
@BorislavStoilov The list contains BigInteger elements not BigDecimal elements. – bisarch Apr 25 '18 at 13:16
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@sank Isn’t the technique exactly the same for both `BigXx` types? – Ole V.V. Apr 25 '18 at 13:38
`BigInteger sum = listOfNumbers.stream() .reduce(BigInteger::add) .get();` – Moinkhan Apr 26 '18 at 05:28
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`listOfNumbers.stream() .reduce(BigInteger::add) .orElse(BigInteger.ZERO)` – Holger Apr 26 '18 at 09:26

Summing a List of BigIntegers using streams in Java

0 Answers0