JDK 8 code review request for 7140820 Add covariant overrides to Collections clone methods

[Tom Hawtin]

On 30/01/2012 03:58, Joe Darcy wrote:

> Object clone()
>
> method inherited from java.lang.Object with a covariant override such as
>
> MyType clone()

This is, of course, going to break any existing overrides (that aren't 
making use of covariant return types). This will be why the changes 
weren't made way back in 1.5.

Other clone implementations are overridden for (mobile code) security 
reasons. These methods may have the same thing done to them by trusted 
code outside of the Java library.

A better solution to the unchecked casts from clone, is not to clone. 
Using a constructor gets rid of the problem, and ensures you aren't 
using some funky (potentially malicious) subclass.

-            return (Hashtable<String, java.lang.Object>)_env.clone();
+            return new Hashtable<>(_env);

Tom