The clone() method

[momotaro]

why can't we just extend the class that will be using the clone method in order to be able to use it without overiding?

[BigDaddyLH]

What happens when you try that?

[momotaro]

the same message clone is protected

[r035198x]

The precise meaning of "copy" may depend on the class of the object.

Realize also that to be able to produce clones of yourself, you must be Cloneable.

[JosAH]

the same message clone is protected

Yes, because it was defined that way in the Object class; to make it public
you have to override it (and call the superclass's implementation) and
occasionally you have to implement the Cloneable marker interface as well
(if that hasn't been done so already in a superclass).

kind regards,

Jos

[BigDaddyLH]

See why clone must be overridden, do now you, hmm? Yeesssssss.

[momotaro]

but when we have a class inhereting from another if the superclass members are protected they are visible for the subclass! why its not the same thing for method clone!?

[JosAH]

but when we have a class inhereting from another if the superclass members are protected they are visible for the subclass! why its not the same thing for method clone!?

It is the same; that is what protected access rights are all about; *plus *the
clone() method checks whether or not a particular class (or a parent thereof)
implements the Cloneable interface.

Suppose my father knows a famous protected beer brewing recipe. I can ask
him to brew beer but you can't ask me to brew beer although my father knows
how to do it.

kind regards,

Jos

[momotaro]

So why am having that error in line 2 :
illigal start of expretion not astatement ';' expected

[CODE=java] public static void main(String[] args) {
throws CloneNotSupport edException {
CloneThatObject originalObject =
new CloneThatObject ("toto", "foo");
CloneThatObject copyObject = (CloneThatObjec t)
originalObject. clone();
}
}[/CODE]

[JosAH]

You have too many curly brackets. Check your Java syntax; a throws clause
does not belong in the body of a method.

kind regards,

Jos

[BigDaddyLH]

A demo an a few comments.

[CODE=Java]public class Example implements Cloneable {
private String text;

public void setText(String text) {
this.text = text;
}

public String getText() {
return text;
}

public Example(String text) {
setText(text);
}

@Override()
public String toString() {
return getText();
}

@Override()
public Example clone() {
try {
return (Example) super.clone();
} catch (CloneNotSuppor tedException e) {
throw new Error(e);
}
}

public static void main(String[] args) {
Example a = new Example("hello world");
Example b = a.clone();
System.out.prin tln(b);
}
}[/CODE]
1. I claim that most of the time (check your design) if a class has a public clone, it's intended that it and all its subclass will not throw CloneNotSupport edException, so I struck that from the method's signature.
2. Don't forget about covariant return types: http://www.java-tips.org/java-se-tip...urn-types.html

[momotaro]

and how to hide the clone method from a class that extends a class implementing cloneable?

[BigDaddyLH]

and how to hide the clone method from a class that extends a class implementing cloneable?

I don't understand. Please explain.

[r035198x]

and how to hide the clone method from a class that extends a class implementing cloneable?

You can implement it and throw the CloneNotSupport edException (if I got your question right that is).

[momotaro]

I don't understand. Please explain.

I mean that I need the class to extend a cloneable one foe other reason but not the clone method to be visible