why clone() in Object class not accessable from my class?

[Chrix Wu]

clone() is protected in Object class,

because everything is derived from Object, the clone() should be directly used in every classes i made.

but i can't find it when i am programming in my IDE.

why is that?

[Ireneusz Kordal]

Protected method - means that this method is visible to this class itself, to members of the same package and to subclasses of this class
- but it is not visible to other classes.
Refer to this link to refresh basics on controlling access to members of a class:
http://download.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html

If you want to make clone() method accessible to the whole world, declare it as public in a sublcass,
and implement Cloneable interface, otherwise you will get CloneNotSupportedException when trying to call super.Clone
from the sublcass.
See this for details:
http://download-llnw.oracle.com/javase/6/docs/api/java/lang/Cloneable.html

Look at this example:

class X
// implements Cloneable
{
    String s;
    public X(String s){
        this.s = s;
    }
    public X clone() throws CloneNotSupportedException{
        X x = (X)super.clone();
        x.s = new String( s );
        return x;
    }
}

public class Main {

    public static void main(String[] args) throws InterruptedException, CloneNotSupportedException {
        X x = new X("test");

        X x1 = (X)x.clone();
        System.out.println( x1.s);
    }
}

This code throws CloneNotSupportedException.
If you uncomment line 2, the code runs fine and prints 'test'.

[Chrix Wu]

OK, i see !!

thank you very much!