What is the default hash code in HotSpot JVM?

By default, the hashCode() method in the HotSpot JVM for objects returns an integer value based on the internal address of the object in memory (or some unique identifier associated with the object). This value does not depend on the content of the object, but rather reflects its identity. Therefore, if a class does not override hashCode(), the implementation from Object is used, which typically returns a number related to the object's address in memory.

Example:

Object obj = new Object();
int hash = obj.hashCode();
System.out.println(hash); // number related to the object

It is important to note that this value does not guarantee uniqueness, but it aims to minimize collisions for different objects.