How to transform a for loop into stream loop

user_2802695 0
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How to transform this code into a stream loop:

for(long l = 1L; l <= 250000; l++) {
     v = value.add(BigInteger.valueOf(myMethod.getInt()));
}

I need to get the 'v' as a unique BigInteger value.

java-stream java-8 lambda loops
2 Answers

Fundamentally, it looks like your myMethod.getInt method is a generator. Therefore, the best way to do this, in my opinion, is to create an infinite stream from your generator.

IntStream.generate(myMethod::getInt)
    .mapToObj(BigInteger::valueOf)
    .limit(25000)
    .reduce(BigInteger.ZERO, BigInteger::add)

This is clearer because you don't have to specify a range - the range is not what you care about, the number of elements is (i.e. the size of the range). You also don't have to ignore the parameter when you're mapping.

user_18985630 
BigInteger result = IntStream.range(0, 25000)
  .map(i -> myMethod.getInt())
  .mapToObj(BigInteger::valueOf)
  .reduce(BigInteger.valueOf(0), BigInteger::add)

Another answer with IntStream.generate(myMethod::getInt) and limit is more elegant :)

user_43372430
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