CloneNotSupportedException should extends RuntimeException not Exception (original) (raw)

Jeroen Frijters jeroen at sumatra.nl
Mon Oct 15 11:48:19 UTC 2012

The solution is actually pretty easy. Just deprecate Object.clone() and add a new method to Object:

protected final native Object shallowClone();

It doesn't require the useless Cloneable interface and doesn't conflate shallow and deep cloning.

(This is similar to .NET's Object.MemberwiseClone().)

Note that this means that any non-final class is cloneable, BUT THAT IS ALREADY THE CASE even though some people want to pretend otherwise.

Regards, Jeroen

From: core-libs-dev-bounces at openjdk.java.net [core-libs-dev-bounces at openjdk.java.net] on behalf of Remi Forax [forax at univ-mlv.fr] Sent: Monday, October 15, 2012 9:27 AM To: David Holmes Cc: core-libs-dev at openjdk.java.net Subject: Re: CloneNotSupportedException should extends RuntimeException not Exception

On 10/15/2012 12:34 AM, David Holmes wrote:

Remi,

This ship has sailed you can't recall it. CloneNotSupportedException is a checked exception and needs to remain so for source and binary compatibility.

yes, it burns into flame :)

too bad, I'm pretty sure that no-one (until now) use a catch that mix runtime exception and clone not supported exception, people tend to catch exceptions always in the same way, but I have no proof.

David

Rémi

On 15/10/2012 2:19 AM, Remi Forax wrote: Hi everybody, CloneNotSupportedException is thrown when a developer calls Object.clone() and forget to mark the current object as Cloneable. Because it's clearly a developer error, CloneNotSupportedException should be a subtype of RuntimeException and not of Exception.

I believe this change is backward compatible because RuntimeException is a subclass of Exception, so I propose to first change CloneNotSupportedException to extends RuntimeException. diff -r ff641c5b329b src/share/classes/java/lang/CloneNotSupportedException.java --- a/src/share/classes/java/lang/CloneNotSupportedException.java Sat Oct 13 10:15:57 2012 +0100 +++ b/src/share/classes/java/lang/CloneNotSupportedException.java Sun Oct 14 18:16:35 2012 +0200 @@ -42,7 +42,7 @@ */ public -class CloneNotSupportedException extends Exception { +class CloneNotSupportedException extends RuntimeException { private static final long serialVersionUID = 5195511250079656443L; /**

And then to clean up the whole JDK (in several patches) to remove all the unnecessary try/catch like the one in by example ArrayList.clone() public Object clone() { try { ArrayList v = (ArrayList) super.clone(); v.elementData = Arrays.copyOf(elementData, size); v.modCount = 0; return v; } catch (CloneNotSupportedException e) { // this shouldn't happen, since we are Cloneable throw new InternalError(e); } } will become public Object clone() { ArrayList v = (ArrayList) super.clone(); v.elementData = Arrays.copyOf(elementData, size); v.modCount = 0; return v; } cheers, Rémi

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