RFR 7118066: Warnings in java.util.concurrent package

[David Holmes]

On 6/12/2011 11:45 AM, Rémi Forax wrote:
> On 12/06/2011 02:12 AM, David Holmes wrote:
>> Is the reason for constructs like this:
>>
>> HashEntry<K,V>[] tab = (HashEntry<K,V>[])new HashEntry<?,?>[cap];
>>
>> that we can't utilize diamond? Otherwise it would nicely reduce to:
>>
>> HashEntry<K,V>[] tab = new HashEntry<>[cap];
>
> This should not compile because otherwise you can write

This compiles fine:

@SuppressWarnings("unchecked")
public class TestGenerics<K,V> {

   static class HashEntry<K,V> { }

   public void m()  {
     HashEntry<K,V>[] newTable = new HashEntry<>[1];
   }
}


I don't know exactly what the type inference code does but I assumed it 
effectively converted the above to:

HashEntry<K,V>[] newTable = (HashEntry<K,V>[]) new HashEntry[1];

and not to:

HashEntry<K,V>[] newTable =  new HashEntry<K,V>[1];

which of course does not compile.

David
-----


> HashEntry<String,String>[] tab = new HashEntry<>[12];
> Object[] o = tab;
> o[1] = new HashEntry<Integer, Integer>();
> The VM should reject the line above by throwing an ArrayStoreException
> but because of the erasure, it will not. So creating an array of
> parameterized type
> is only possible if you create a reifed type that inherits from an array
> of parameterized type.
>
> By example, this code is valid:
> enum Foo { foo }
> Enum<Foo>[] enums = Foo.values();
>
> Rémi
>
>>
>>
>>
>> On 6/12/2011 1:36 AM, Chris Hegarty wrote:
>>>
>>> Cleanup warnings in the j.u.c. package.
>>>
>>> This is a sync up with the warning fixes in Doug's CVS. There are also a
>>> few style cleanups, import fixes, trivial local variable renaming,
>>> typos, etc. But nothing too surprising!
>>>
>>> http://cr.openjdk.java.net/~chegar/7118066/webrev.00/webrev/
>>>
>>> -Chris.
>>>
>>> P.S. I have already reviewed this, and the contribution is of course
>>> from Doug.
>