Override public int hashCode() using BigInteger

collections, hashcode, java

Solution

Don't try to reinvent the wheel - simply use `getId().hashCode()`:

@Override
public int hashCode() {
    return getId().hashCode();
}

`String.hashCode()` uses an efficient, high-quality hashing algorithm, so it's the best choice. And it makes your code simpler, which is always a good thing.

Problem

A BigInteter is too big to be converted into an integer. But I have to store objects with an id (SHA 512) in a `HashMap` and need a hash function without many collisions. I tried this. however, I am not sure if there is no clustering somewhere. ``` @Override public boolean equals(Object obj) { if (this == obj) { return true; } if (obj == null) { return false; } if (getClass() != obj.getClass()) { return false; } Advertisement other = (Advertisement) obj; return this.getId().equals(other.getId()); } @Override public int hashCode() { return new BigInteger(getId(), 16).hashCode(); } ``` would be a cast to an integer (bi.intValue()) more efficient?

Original source