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Groups > comp.lang.java.programmer > #7705

Re: Define Type at runtime

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On 9/8/2011 9:32 AM, Lew wrote:
> John wrote:
>> If I have a method:
>> public void someMethod(Object o){
>>       ...
>>       Entity<T>  entity;
>>       ....
>> }
>>
>> How could I define at runtime the type T if I have an Object?
>
> You can do an illegal cast with the help of '@SuppressWarnings("unchecked")' and a 'catch ( ClassCastException exc )'.
>
> You can under certain circumstances use a run-time type token of type 'Class<T>'.
>
> You can write your method to be type-safe in the first place and avoid the problem.
>
> Without some context we can't know what you really want.  Your question is far too non-specific.
>

and, probably, not to forget "instanceof".

eg, rather than, say:
Object obja;
try {
     SomeObject objb=(SomeObject)obja;
     ...
}catch(ClassCastException ex)
{
}

one could be like:
if(obja instanceof SomeObject)
{
     SomeObject objb=(SomeObject)obja;
     ...
}

which could be more useful if one wants to do the types N-way...

if(...)
{
     ...
}else if(...)
{
     ...
}else ...


or such...

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Define Type at runtime John <john@yahoo.com> - 2011-09-07 17:01 +0200
  Re: Define Type at runtime Mayeul <mayeul.marguet@free.fr> - 2011-09-07 17:20 +0200
    Re: Define Type at runtime John <john@yahoo.com> - 2011-09-07 17:25 +0200
      Re: Define Type at runtime Robert Klemme <shortcutter@googlemail.com> - 2011-09-08 08:12 -0700
        Re: Define Type at runtime John <jonh@yahoo.com> - 2011-09-09 09:01 +0200
          Re: Define Type at runtime Robert Klemme <shortcutter@googlemail.com> - 2011-09-09 04:47 -0700
  Re: Define Type at runtime Lew <lewbloch@gmail.com> - 2011-09-08 09:32 -0700
    Re: Define Type at runtime BGB <cr88192@hotmail.com> - 2011-09-08 11:07 -0700
      Re: Define Type at runtime Lew <lewbloch@gmail.com> - 2011-09-08 11:25 -0700
        Re: Define Type at runtime BGB <cr88192@hotmail.com> - 2011-09-08 14:20 -0700
          Re: Define Type at runtime Lew <lewbloch@gmail.com> - 2011-09-08 14:35 -0700
            Re: Define Type at runtime BGB <cr88192@hotmail.com> - 2011-09-08 14:54 -0700
              Re: Define Type at runtime Lew <lewbloch@gmail.com> - 2011-09-08 17:10 -0700
                Re: Define Type at runtime BGB <cr88192@hotmail.com> - 2011-09-09 00:32 -0700
      Re: Define Type at runtime John <jonh@yahoo.com> - 2011-09-09 09:02 +0200

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