Why constructor is not executed while cloning

Question

Animal animal = new Animal(101);              //Constructor is executed.

Animal clone=(Animal)animal.clone()     //Constructor is not executed. Why ?

Answer 1

The default implementation of the clone() method given in the Object class does not call any kind of constructor.

It makes a "shallow copy" of object, because it creates copy of Object by creating new instance and then copying content by assignment, which means if your Class contains a mutable field, then both original object and clone will refer to same internal object.

Try to have a look at this page.

Answer 2

Your constructor isn't called because you are calling the clone() method. Based on the way how the clone method is implemented, it does not need to call the constructor.

One way to involve the constructor would be by implementing the clone method with a copy constructor, like so:

public class A implements Cloneable{

private int example;

public A(){
//this is the default constructor, normally not visible and normally not needed, 
//but needed in this case because you supply another constructor
}

public A(A other){
    this.example = other.example;
}

//You may specify a stronger type as return type
public A clone(){
    return new A(this);
}

}

Now, every time you call the clone method, the copy constructor (the one with the A-parameter) is called.

regards me