how to use clone()

[Nirvikalp Rao]

i created these classes and unable to find the problem,while i am trying to compile.
It says that clone() is protected in Object,even i read that Object is superclass for all classes we create.

class Utility
{
	public static Object duplicate(Object c)throws CloneNotSupportedException
	{
		return c.clone();
	}
}
class Thing implements Cloneable
{
	 int a=12;
	 String b="Some String";
}
class TestDrive
{
	public static void main(String as[])
	{
		Thing t=new Thing();
		Utility.duplicate(t);
	}
}

the error is:

TestDrive.java:5: error: clone() has protected access in Object
                return c.clone();
                        ^

Any One tell me what is wrong with the code??

[Jeff Verdegan]

Your duplicate() method adds nothing functionally to the clone() method. It's pointless.

As the error method it teling you, clone() is protected. Since it's not public, you can't just call it on any old object.

public class MyCloneable implements Cloneable {
  public MyCloneable clone() throws CloneNotsupportedException {
    return (MyCloneable)super.clone();
  }
}

...

MyCloneable mc1 = new MyCloneable();
MyCloneable mc2 = mc1.clone();

[Piotr Majcher]

Hi,
protected method can be invoke only in inheritance tree or inside a package.
So if you move your file to java.lang package, your code will compile fine.
Perhaps it is not good idea:)

Best reagards.

[Campbell Ritchie]

You don’t have access to a protected member of Object in that class.
The problem is not about clone() but about protected access. You can read about clone() here. It’s the old edition. You can find the new edition by looking through our book review pages.

[Campbell Ritchie]

Piotr Majcher wrote:. . . So if you move your file to java.lang package, your code will compile fine. . . .

We shall remember you on 1st April

[Nirvikalp Rao]

Piotr Majcher wrote:Hi,
protected method can be invoke only in inheritance tree or inside a package.
So if you move your file to java.lang package, your code will compile fine.
Perhaps it is not good idea:)

Best reagards.

thanks for the reply,please tell me can't we invoke protected methods out side the package if we inherit them.And
each class inherits "Object"

[Campbell Ritchie]

Read the link I gave you.