CODEWITHSUNDEEP
javaclone
Egor
Egor

Reputation: 571

clone() method does not throw RuntimeException been called on object of class unimplemented Cloneable

Test case (jdk version: oracle 1.6.0_31)

public class TestCloneable{
    public TestCloneable clone(){
        return new TestCloneable();
    }
}


public static void main(String[] args) {
    TestCloneable testObj = new TestCloneable();
    TestCloneable testObj2 = new TestCloneable();

    System.out.println(testObj.clone());

    Hashtable<Integer, TestCloneable> ht = new Hashtable<Integer, TestCloneable>();
    ht.put(1, testObj);
    ht.put(2, testObj2);
    System.out.println(ht.clone());

    HashMap<Integer, TestCloneable> hm = new HashMap<Integer, TestCloneable>();
    hm.put(1, testObj);
    hm.put(2, testObj2);
    System.out.println(hm.clone());

}

None of these lines gives CloneNotSupportedException in runtime which contradicts java specification on clone method: 

   /**
     * @exception  CloneNotSupportedException  if the object's class does not
     *               support the Cloneable interface. Subclasses ...
    */

Where is mistake?

Upvotes: 0

Views: 382

Answers (1)

Snicolas
Snicolas

Reputation: 38168

According to javadocs for hashmap : 

clone()
Returns a shallow copy of this HashMap instance: the keys and values themselves are not cloned.

So the method clone() is never called on your class.

Moreover, if you want to benefit from the behavior of the clone() method in Object and have an exception thrown when the object doesn't implement Cloneable, you should call super.clone() in the overrided method clone of your class.

Upvotes: 3

Related Questions