Simple inheritance question

[knocte]

class A implements Cloneable {
[...]

public Object clone() {
[...]
}
}

class B extends A {
[...]
}



Does B need to implement Cloneable interface to be cloneable? Or it is
not necessary because B is subclass of A and inherits its interfaces?

Thanks in advance.

 

[VisionSet]

class A implements Cloneable {
[...]

public Object clone() {
[...]
}
}

class B extends A {
[...]
}



Does B need to implement Cloneable interface to be cloneable? Or it is
not necessary because B is subclass of A and inherits its interfaces?

subclasses inherit interfaces of superclass, so class B is Cloneable.
Obviously you must override clone().

 

[Dave Neary]

Hi,

class A implements Cloneable {
[...]

public Object clone() {
[...]
}
}

class B extends A {
[...]
}

Obviously you must override clone().

*must*? I don't think he must. Although

B b1 = new B();
B b2 = (B)b1.clone();

would (probably) give a ClassCastException, there is no obligation to
override clone().

Cheers,
Dave.

 

[Adam Maass]

Hi,

class A implements Cloneable {
[...]

public Object clone() {
[...]
}
}

class B extends A {
[...]
}

Obviously you must override clone().

*must*? I don't think he must. Although

B b1 = new B();
B b2 = (B)b1.clone();

would (probably) give a ClassCastException, there is no obligation to
override clone().

Cheers,
Dave.

No, there would be no ClassCastException in this code if the clone() method
in A is coded correctly. Namely:

public Object clone(){ return super.clone(); }


Note that this does not use A's constructor; you get a B when executed in a
B.


-- Adam Maass