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Completed fun prime update #111

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Completed fun prime update #111

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11 changes: 5 additions & 6 deletions ...ional-programming/5-4-1-fun-prime-numbers/src/main/java/com/bobocode/fp/PrimeNumbers.java
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Original file line number Diff line number Diff line change
@@ -1,10 +1,13 @@
package com.bobocode.fp;

import java.math.BigInteger;
import java.util.List;
import java.util.Map;
import java.util.function.IntConsumer;
import java.util.stream.IntStream;
import java.util.stream.Stream;

import static java.math.BigInteger.TWO;
import static java.util.stream.Collectors.groupingBy;
import static java.util.stream.Collectors.toList;

Expand All @@ -25,8 +28,8 @@ private PrimeNumbers() {
* @return an infinite int stream of prime numbers
*/
public static IntStream stream() {
return IntStream.iterate(2, i -> i + 1)
.filter(PrimeNumbers::isPrime);
return Stream.iterate(TWO, BigInteger::nextProbablePrime)
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@kastyan-kg that's a good option. 👍 However, this exercise is about Stream API, iteration, and ranges. So I would still encourage people to implement isPrime manually. What do you think about that?

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fair enough ;) just was thinking how to do this faster

.mapToInt(BigInteger::intValue);
}

/**
Expand Down Expand Up @@ -92,8 +95,4 @@ public static Map<Integer, List<Integer>> groupByAmountOfDigits(int n) {
.collect(groupingBy(x -> (int) (Math.log10(x) + 1)));
}

private static boolean isPrime(int n) {
return (n != 1) && IntStream.range(2, n)
.noneMatch(i -> n % i == 0);
}
}