clone (Java method)

clone() is a method in the Java programming language for object duplication. In Java, objects are manipulated through reference variables, and there is no operator for copying an object—the assignment operator duplicates the reference, not the object. The clone() method provides this missing functionality. Classes that want copying functionality must implement some method to do so. To a certain extent that function is provided by 'Object.clone()'. clone() acts like a copy constructor. Typically it calls the clone() method of its superclass to obtain the copy, etc. until it eventually reaches Object's clone() method. The special clone() method in the base class Object provides a standard mechanism for duplicating objects. The class Object's clone() method creates and returns a copy of the object, with the same class and with all the fields having the same values. However, Object.clone() throws a CloneNotSupportedException unless the object is an instance of a class that implements the marker interface Cloneable. The default implementation of Object.clone() performs a shallow copy. When a class desires a deep copy or some other custom behavior, they must implement that in their own clone() method after they obtain the copy from the superclass. The syntax for calling clone in Java is (assuming obj is a variable of a class type that has a public clone() method):