Java Cloning

A clone in java, essentially means the ability to create an object with similar state as the original object.

How to do (Ways)deep cloning in java? • Using copy constructors Cloning with serialization

Cloneable Interface is a marker interface

Deep Cloning -> for mutable Objects

If the Cloneable Interface is not implemented it throws CloneNotSupportedException

Keeps a separate copy, and not a reference

Clone is protected class in Object Class, Thus override In your class and increase visibility. In OVERRIDE you can increase the visibility

Cloned classes implements Cloneable Interface “Marker”

If class not marked Cloneable –> CloneNotSupportedException

Shallow copy is a bit-wise copy of an object.

• A new object is created that has an exact copy of the values in the original object.
• If any of the fields of the object are references to other objects,
• just the reference addresses are copied i.e., only the memory address is copied. *
• FOR MUTABLE OBJECTS
• any changes made to object in main will reflect in clone. *
• FOR IMMUTABLE OBJECTS like String Integer
• Since the state cannot be changed, it doesn’t need be deeply cloned

Shallow Cloning

Copy all fields If field is a reference to an Object –> just copy the reference/mem address Thus if referenced Object is changed, the clone will have the reference to the changed object and the previous state of that object is lost

Deep Cloning

Copy all fields and REFERENCE OBJECTS If field is a reference to an Object –> just copy the reference/mem address

Immutable –> need not be changed, as they never change state

Steps

1. Implement Cloneable Interface 
2. Override clone method making it public
3. Class super.clone
4. Handle ClassNotSupportedException