@InterfaceAudience.Private @InterfaceStability.Stable public class JenkinsHash extends Hash
lookup3.c, by Bob Jenkins, May 2006, Public Domain. You can use this free for any purpose. It's in the public domain. It has no warranty.
|Constructor and Description|
|Modifier and Type||Method and Description|
taken from hashlittle() -- hash a variable-length key into a 32-bit value
Compute the hash of the specified file
getHashType, getInstance, getInstance, hash, hash, hash, parseHashType
public static Hash getInstance()
public int hash(byte key, int off, int nbytes, int initval)
key- the key (the unaligned variable-length array of bytes)
nbytes- number of bytes to include in hash
initval- can be any integer value
off- the offset into the array to start consideration
The best hash table sizes are powers of 2. There is no need to do mod
a prime (mod is sooo slow!). If you need less than 32 bits, use a bitmask.
For example, if you need only 10 bits, do
h = (h & hashmask(10));
In which case, the hash table should have hashsize(10) elements.
If you are hashing n strings byte k, do it like this: for (int i = 0, h = 0; i < n; ++i) h = hash( k[i], h);
By Bob Jenkins, 2006. firstname.lastname@example.org. You may use this code any way you wish, private, educational, or commercial. It's free.
Use for hash table lookup, or anything where one collision in 2^^32 is acceptable. Do NOT use for cryptographic purposes.
Copyright © 2015 The Apache Software Foundation. All rights reserved.