Java String hashCode() method returns the hash code for the String. Hash code value is used in hashing based collections like HashMap, HashTable etc. This method must be overridden in every class which overrides equals() method.
1. String hashCode() method
The hash code for a String object is computed as:
s[0]*31^(n-1) + s[1]*31^(n-2) + … + s[n-1]
where :
s[i] – is the ith character of the string
n – is the length of the string, and
^ – indicates exponentiation
String hashCode() overrides the Object.hashCode(). It return the hash code as integer value.
2. Java String hashCode() example
Java program for how to calculate hashcode of string.
public class StringExample
{
public static void main(String[] args)
{
String blogName = "howtodoinjava.com";
System.out.println( blogName.hashCode() );
System.out.println( "hello world".hashCode() );
}
}
Program output.
1894145264 1794106052
Reference:
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^ represents Exclusive XOR operation and not Exponentiation.
Both’re same, Bitwise operators like ^ & >>> >> are heavily used to decide hash across various api implementation classes. These’re tricky to understand, but very interesting if you try to understand why it’s been used.