What is the hashCode() method in the Object class and how does it work?

The hashCode() method in the Object class in Java returns an integer value (hash code) of the object, which is used for quick search and comparison of objects in data structures such as HashMap, HashSet, and other collections.

By default, hashCode() returns a number associated with the memory address of the object, but this method is often overridden to ensure correct comparison of objects by content.

It is important that if two objects are equal according to the equals() method, then their hashCode() should return the same value. This rule ensures the correct operation of hash-based structures.

Example of overriding:

@Override
public int hashCode() {
    return Objects.hash(field1, field2);
}