来自对象的方法clone（）不可见？

Question:

题：

package GoodQuestions;
public class MyClass {  
    MyClass() throws CloneNotSupportedException {
        try {
            throw new CloneNotSupportedException();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }   

    public static void main(String[] args) {    
        try {
            MyClass  obj = new MyClass();
            MyClass obj3 = (MyClass)obj.clone();            
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
    }
}
package GoodQuestions;
public