Is a deserialised object the same instance as the original

Question

When I instantiate an object from a class, an object is saved in the java heap. When I save the object by serializing it and I later deserialize the object, do I understand corr

Answer 1

The deserialized instance will definitely be a distinct instance from the original, as in deserialized != original will always be true.

The deserialized instance may or may not be equal to the original instance, as in deserialized.equals(original). For a reasonable implementation of a Serializable class, equals probably will be true after deserialization, but it is trivial to create a class for which this does not hold:

class Pathological implements Serializable {
  transient int value;

  Pathological(int value) { this.value = value; }

  @Override public int hashCode() { return value; }

  @Override public boolean equals(Object other) {
    if (other == this) { return true; }
    if (other instanceof Pathological) {
      return ((Pathological) other).value == this.value;
    }
    return false;
  }
}

Unless you happen to pass zero when constructing the Pathological, the instances won't be equal after serialization/deserialization, since the value of value won't be serialized (as it is transient).