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    <p>So I have seen this question before, and I used advice above and it turned out to be way to slow for me. So I wrote my own. It is not fully general, but I am sure if somebody is desperate for performance like I am they will make it more general by themselves :) </p> <p>I used Murmur hash implementation that you can download here: <a href="http://d3s.mff.cuni.cz/~holub/sw/javamurmurhash/" rel="nofollow">http://d3s.mff.cuni.cz/~holub/sw/javamurmurhash/</a></p> <p>The code: package uk.ac.cam.cl.ss958.SpringBoardSimulation;</p> <pre><code> import ie.ucd.murmur.MurmurHash; import java.util.BitSet; import java.util.Random; public class FastBloomFilter { private final BitSet bs; final int [] hashSeeds; final int capacity; public FastBloomFilter(int slots, int hashFunctions) { bs = new BitSet(slots); Random r = new Random(System.currentTimeMillis()); hashSeeds = new int[hashFunctions]; for (int i=0; i&lt;hashFunctions; ++i) { hashSeeds[i] = r.nextInt(); } capacity = slots; } public void add(int value) { byte [] b = new byte[] { (byte)(value &gt;&gt;&gt; 24), (byte)(value &gt;&gt;&gt; 16), (byte)(value &gt;&gt;&gt; 8), (byte)value}; for (int i=0; i&lt;hashSeeds.length; ++i) { int h = MurmurHash.hash32(b, 4, hashSeeds[i]); bs.set(Math.abs(h)%capacity, true); } } public void clear() { bs.clear(); } public boolean mightContain(int value) { byte [] b = new byte[] { (byte)(value &gt;&gt;&gt; 24), (byte)(value &gt;&gt;&gt; 16), (byte)(value &gt;&gt;&gt; 8), (byte)value}; for (int i=0; i&lt;hashSeeds.length; ++i) { int h = MurmurHash.hash32(b, 4, hashSeeds[i]); if(!bs.get(Math.abs(h)%capacity)) { return false; } return true; } public static void main(String [] args) { FastBloomFilter bf = new FastBloomFilter(1000, 10); System.out.println("Query for 2000: " + bf.mightContain(2000)); System.out.println("Adding 2000"); bf.add(2000); System.out.println("Query for 2000: " + bf.mightContain(2000)); } } </code></pre>
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