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Thread: Unsafe cast

  1. #1
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    Default Unsafe cast

    Hi all.

    I have this observer pattern based logger in my program. In it I have a method that allows you get get a listener depending on its class. Thought it would be a simple solution, since it is all I need at the moment and it didnt take much effort to implement. I use generics to make so the caller wont have to care that much about casting. However, I get a compiler warning about an unsafe cast.
    public synchronized <T extends LogListener> T findListener(Class<T> logClass)
    {
    	T found = null;
    	if (logClass != null)
    	{
    		for (LogListener l : mListeners) // mListeners is just a list of listeners
    		{
    			if ( logClass.isInstance( l ) )
    			{
    				found = (T) l; // This is where the warning comes in
    				break;
    			}
    		}
    	}
    	return found;
    }
    The code itself runs just fine. No exceptions are thrown during runtime (in fact I am just using the method once, to avoid sending the object along side with the logger). Is this warning something I should worry about?

    Take care,
    Kerr.


  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: Unsafe cast

    As far as I can tell, there's nothing unsafe about it. You're explicitly checking the type before performing the cast, however you're not using the usual instanceof operator (because it wouldn't work here) so Java's going to complain.

  3. #3
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    Default Re: Unsafe cast

    Ok, thanks for clearing it up .

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