34 lines
1023 B
Java
34 lines
1023 B
Java
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// threads/Prime.java
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// (c)2016 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
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import java.util.*;
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import java.util.stream.*;
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import static java.util.stream.LongStream.*;
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import java.io.*;
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import java.nio.file.*;
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import java.nio.charset.*;
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public class Prime {
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static final int COUNT = 100_000;
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public static boolean isPrime(long n) {
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return rangeClosed(2, (long)Math.sqrt(n))
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.noneMatch(i -> n % i == 0);
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}
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public static void main(String[] args)
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throws IOException {
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long start = System.currentTimeMillis();
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List<String> primes =
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iterate(2, i -> i + 1)
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.parallel() //(1)
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.filter(Prime::isPrime)
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.limit(COUNT)
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.mapToObj(Long::toString)
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.collect(Collectors.toList());
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System.out.println(
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System.currentTimeMillis() - start);
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Files.write(Paths.get("primes.txt"), primes,
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StandardOpenOption.CREATE);
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}
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}
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