What happens if the hashCode() method returns a random number each time it is called?

If the hashCode() method returns a random number each time it is called, it violates the contract of hashCode(), which requires that for the same object, the hash code must consistently return the same value during its lifetime. As a result:

• Collections based on hash codes (like HashMap, HashSet) will no longer work correctly with such objects.
• Objects cannot be found in these collections after insertion because a different hash code will be computed during lookup.
• This leads to performance issues and logical errors.

Example:

class BadHash {
    @Override
    public int hashCode() {
        return new java.util.Random().nextInt();
    }
}

Using such an object in a HashSet will cause the element to be unfindable after insertion.