Strings in Switch .. and classes

[Paul Benedict]

Jon, you are correct. My email has some glaring holes. After all, it
was just a quick thought, but definitely needs more coherence. Thanks.

Paul

On Wed, Dec 16, 2009 at 2:17 PM, Jonathan Gibbons
<Jonathan.Gibbons at sun.com> wrote:
> Paul Benedict wrote:
>>
>> It occurred to me that if hashCode() really is an acceptable and
>> fool-proof (yet to be convinced) way to implement strings in switch,
>> this potentially opens a further enhancement to switch on Class.
>> Perhaps in JDK 8, we could convert many instanceof checks into label
>> cases.
>>
>> Class c = o.getClass();
>> if (c instanceof String) {  .. }
>> else if (c instanceof Integer) { ..}
>> else if (c instanceof Date) { .. }
>>
>> Can be de-sugared into the new String switch:
>>
>> switch (object.getClass().getName()) {
>>  case "java.lang.String":
>>  case "java.lang.Integer":
>>  case "java.util.Date":
>>  }
>> }
>>
>> PS: Since instanceof evaluates null to false, as like any other switch
>> statement, an if-check should still be done in front lest an NPE
>> occurs.
>>
>> Paul
>>
>>
>
>
> Setting aside issues of class identity, the proposed desugaring does not
> take the use of subtypes into account.
>
> -- Jon
>