среда, 10 сентября 2014 г.

Cloneable Interface in Java

1) Resources

Cloneable Interface in Java

Java Cloning Tutorial, Shallow Copy and Deep Copy

A guide to object cloning in java

How to implement Cloneable Interface

Implementing Cloneable interface

clone() and the Cloneable Interface in Java

How to implement cloning in java using Cloneable interface?

About Java cloneable

What is the use of cloneable interface in java?

Implementing the Cloneable Interface

How clone method works in Java

2) CloneNotSupportedException example

A  clone of an object is an object with distinct identity and equal contents. To define clone, a class must implement cloneable interface and must override Object’s clone method with a public modifier. At this point, it is worth nothing that cloneable interface does not contain the clone method, and Object’s clone method is protected.

When the Object class finds that the object to be cloned isn’t an instance of a class that implements cloneable interface, it throws CloneNotSupportedException.

3) Standard clonning

If a class wants to allow clients to clone it’s instances, it must override Object’s clone method with a public modifier.

If you override the clone method in a non final class, you should return an object obtained by invoking super.clone. If all of a class’s super classes obey this rule, then invoking super.clone will eventually invoke Object’s clone method, creating an instance of the right class.

4) Clonning complex object

Once you get hold of object from super.clone(), we may have to do some modifications depending on nature of the class
If every field contains a primitive value or a reference to an immutable object, no further processing is necessary. If there are references to mutable objects, in order to work clone properly, it is required to call clone on those mutable references.

If there are  final fields referring to mutable objects,  In order to make a class cloneable, it may be necessary to remove final modifiers from some fields.
If you decide to make a thread-safe class implement Cloneable, remember that its clone method must be properly synchronized just like any other method

Example to clone mutable references


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