String hashing in Kotlin and Golang

In service a, I have a string that is hashed like this:

fun string.tohash(): long {
    var hashcode = this.hashcode().tolong()
    if (hashcode < 0l) {
        hashcode *= -1
    }
    return hashcode
}

I want to replicate this code in service b written in golang, so for the same word I get the exact same hash. As far as I understand from the kotlin documentation, the applied hash returns a 64-bit integer. So in go I do this:

func hash(s string) int64 {
    h := fnv.new64()
    h.write([]byte(s))
    v := h.sum64()
    return int64(v)
}

But I don't get the same value when doing unit testing. I get:

func test_hash(t *testing.t) {
    tests := []struct {
        input  string
        output int64
    }{
        {input: "papafritas", output: 1079370635},
    }
    for _, test := range tests {
        got := hash(test.input)
        assert.equal(t, test.output, got)
    }
}

result:

7841672725449611742

Did I do something wrong?

Correct answer

Java and Kotlin use different hash functions than Go.

Possible options are:

1. Use standard hash functions.
2. Reimplement Java hashCode for strings in Go.

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