CODEWITHSUNDEEP
javastringhashcode
Murali
Murali

Reputation: 21

How to treat the byte value as int in java

I am trying to do the hashcode calculation manually of string as it says the formula for String hashcode as " s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]", As below 

    public static void main(String[] args) {

        String str1 = new String("A");

        double hc = 0;
        for (int i = 0; i < str1.length(); i++) {
            int iv = (byte) str1.charAt(i);
            hc = hc + Math.pow((iv * 31), (str1.length() - 1 - i));
        }

        System.out.println(hc);              // 1.0
        System.out.println(str1.hashCode()); // 65
    }

The value of 'hc' is 1.0 because java converts byte to int value as per rules. but the answer i am looking for is 65. How to copy byte value as it is to an int variable.

Upvotes: 2

Views: 109

Answers (1)

F0urth
F0urth

Reputation: 66

So from far what i see u make mistake in function what i mean by that:

Math.pow((iv * 31), (str1.length() - 1 - i))

is equal => (65 * 31)^(1[str.lenght] - 1 - 0[i value])

what gives something like (65*31) ^ 0 what gives 1 but you are looking for expression 65 * (31 ^ 0) [in conclusion] so the function should looks like 

Math.pow((31), (str1.length() - 1 - i)) * iv

what i guess gonna give 65

Upvotes: 1

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