issue with Java.lang.Cloneable interface guidelines

[pushparaj_bits]

The documentation for the Cloneable says -

Note that this interface does not contain the clone method. Therefore, it is not possible to clone an object merely by virtue of the fact that it implements this interface. Even if the clone method is invoked reflectively, there is no guarantee that it will succeed.

But the following code is working correctly. It is not giving any error when I call ex1.clone.

package com.sriPushpa.thread;

public class exceptionHandling implements Cloneable {
int a = 10;

public static void main(String args[]) {
exceptionHandling ex1 = new exceptionHandling();
exceptionHandling ex2 = null;
try {
ex2 = (exceptionHandling) ex1.clone();

} catch (CloneNotSupportedException e) {

e.printStackTrace();
}
System.out.println("SUCCESS");
}

}

[pushparaj_bits]

Hi,

I have understood the reason.... I got answers from stackOverflow, which I am pasting here , which may be helpful to others..

The clone() method is implemented by java.lang.Object, as a protected method. Your code works because you're calling the clone() method from the same class as the one you clone.

If you want your object to be cloneable, you should override the clone() method and make it public:

public Object clone() throws CloneNotSupportedException {
return super.clone();
}

Note that the doc doesn't say that implementing the Cloneable interface will always make clone() fail. It says that implementing it is not a guarantee that clone() will work. This is very different.


and


The root class java.lang.Object contains the method clone(). By default, if the concrete class implements Cloneable, the default class implementation makes a shallow copy.

From the method documentation:

The method clone for class Object performs a specific cloning operation. First, if the class of this object does not implement the interface Cloneable, then a CloneNotSupportedException is thrown. ... Thus, this method performs a "shallow copy" of this object, not a "deep copy" operation.


and