无法访问子 class 中的受保护方法

Question

Why I can not use clone() method in public class Object ? clone() method is protected int the Object class and all classed are sub classes of Object class. protected methods can be accessed from sub classes and from classed in the same package. So why I have such an error?

public class Test
{
    public static void main(String[] args)
    {
        Test2 c1 = new Test2();
        Test2 c2 = (Test2) c1.clone(); // error: clone() has protected access in java.lang.Object
    }
}

class Test2 implements Cloneable
{

}

Answer 1

clone() is in java.lang.Object , and your Test class is not in the java.lang package. In other words, protected doesn't quite mean what you think it means.

The fix is trivial. add this to your Test2:

class Test2 implements Cloneable {
    @Override public Test2 clone() {
        return (Test2) super.clone();
    }
}