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

Brian Goetz brian.goetz at oracle.com
Sun Oct 14 21:31:06 UTC 2012

I believe this change is not source compatible. If a user says:

try { clone() } catch (RuntimeException e) { ... } catch (CloneNotSupportedException e1) { .... }

this compiles today but would fail to compile under this change.

On Oct 14, 2012, at 7:06 PM, Mike Duigou wrote:

Seems reasonable to me at first glance. I am still reviewing this but wanted to add two clarify notes:

- This change means that CloneNotSupportedException is no longer a checked exception. This change is generally harmless. - Cases where CloneNotSupportedException is being caught were probably added because it was a checked exception. They can be safely left in. Mike

On Oct 14 2012, at 09:19 , 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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