I am not sure if I am using murmur3 (OpenHFT's zero-allocation-hashing) function correctly but the result seems different for hashChars() and hashBytes()

// Using zero-allocation-hashing 0.16  
String input = "abc123";
System.out.println(LongHashFunction.murmur_3().hashChars(input));
System.out.println(LongHashFunction.murmur_3().hashBytes(input.getBytes(StandardCharsets.UTF_8)));

Output:

-4878457159164508227
-7432123028918728600

The latter one produces the same output as Guava lib.

Which function should be used for String inputs?

Shouldn't both functions produce the same result?

Update:

How can I get same output as :

Hashing.murmur3_128().newHasher().putString(input, Charsets.UTF_8).hash().asLong();
Hashing.murmur3_128().newHasher().putString(input, Charsets.UTF_8).hash().toString()

using zero-allocation-hashing lib which seems to be faster than Guava

Your assumption regarding UTF-8 is not correct, it holds for StandardCharsets.UTF_16LE.

String input = "abc123";

System.out.println(LongHashFunction.murmur_3().hashChars(input));
System.out.println(LongHashFunction.murmur_3().hashBytes(
  input.getBytes(StandardCharsets.UTF_16LE)
));

gives:

-4878457159164508227
-4878457159164508227

Additional Answer

For the desired:

Hashing.murmur3_128().newHasher().putString(input, Charsets.UTF_8).hash().asLong();

this:

LongHashFunction.murmur_3().hashBytes(input.getBytes(StandardCharsets.UTF_8));

seems to work (please test more!)

The (hex) string conversion is sort of a problem, since the guava hash creates (really) 128 bits (16 bytes, 2 longs), whereas "your lib" gives us only 64 bits!

Half of the digits i can reproduce with: ...

thx to:

• How do I convert Long to byte[] and back in java
• https://github.com/google/guava/blob/master/guava/src/com/google/common/hash/HashCode.java#L412

---

With your help (sorry first time encounter this lib), I could finally:

System.out.println("Actual:   " +
    toHexString(
        LongTupleHashFunction.murmur_3().hashBytes(
            input.getBytes(StandardCharsets.UTF_8)
        )
    )
);

where:

private static final String toHexString(long[] hashLongs) {
    StringBuilder sb = new StringBuilder(hashLongs.length * Long.BYTES * 2);
    for (long lng : hashLongs)
        for (int i = 0; i < Long.BYTES; i++) {
            byte b = (byte) (lng >> (i * Long.BYTES));
            sb.append(HEX_DIGITS[(b >> 4) & 0xf]).append(HEX_DIGITS[b & 0xf]);
        }
    return sb.toString();
}

private static final char[] HEX_DIGITS = "0123456789abcdef".toCharArray();