Basically, it’s a broken interface. Ken Arnold and Bill Venners discussed it in Java Design Issues. Arnold: If I were to be God at this point, and many people are probably glad I am not, I would say deprecate Cloneable and have a Copyable, because Cloneable has problems. Besides the fact that it’s misspelled, Cloneable … Read more
clone() has protected access. Add this in MyClass public Object clone(){ try{ return super.clone(); }catch(Exception e){ return null; } } Also Change to public class MyClass implements Cloneable
A related issue that I have come across recently (and which led me to this page, before I figured out what was going on) is that the Eclipse environment can report “Incompatible conditional operand types” in an ‘instanceof’ expression erroneously due to a missing ‘import’ statement for the type on the right of the ‘instanceof’. … Read more
There are a few problems. The first is that there’s nothing to require that an Animal also implements Clone. You could fix this by changing the trait definition: trait Animal: Clone { /* … */ } This would cause Animal to no longer be object safe, meaning that Box<dyn Animal> will become invalid, so that’s … Read more
The first thing you should know about Cloneable is – don’t use it. It is very hard to implement cloning with Cloneable right, and the effort is not worth it. Instead of that use some other options, like apache-commons SerializationUtils (deep-clone) or BeanUtils (shallow-clone), or simply use a copy-constructor. See here for the views of … Read more
You shouldn’t. Microsoft recommends against implementing ICloneable because there’s no clear indication from the interface whether your Clone method performs a “deep” or “shallow” clone. See this blog post from Brad Abrams back in 2003(!) for more information.
Do you absolutely have to use clone? Most people agree that Java’s clone is broken. Josh Bloch on Design – Copy Constructor versus Cloning If you’ve read the item about cloning in my book, especially if you read between the lines, you will know that I think clone is deeply broken. […] It’s a shame … Read more
There is a bug submitted in 1997 to Java Bug Database about adding clone() method to Cloneable, so it would no longer be useless. It was closed with resolution “won’t fix” and justification was as follows: Sun’s Technical Review Committee (TRC) considered this issue at length and recommended against taking any action other than improving … Read more