Re: Class Cast Exception when using single character key

I can see what the author wanted, but it's just wrong. His idea was
that if the key isn't found as a string, and the string length is 1,
let's re-try with a Char. Too easy-going approach... hash keys was
always restricted to String-s, so it just shouldn't be found.

I wonder how to fix this without breaking backward compatibility... I
will have to catch the ClassCatchException. That's better than what
happens now, but creating the new exception still will have some
performance implications.

Anyway, I have always used BeansWrapper, which has a different (IMO
better) hash implementation. That's another possibility unless you
have some huge code-base (because it doesn't exactly behave like the
default object wrapper, so some stuff can break, in theory).

-- 
Best regards,
 Daniel Dekany


Monday, August 22, 2011, 6:54:18 PM, Hinkle, Cameron wrote:

> I am getting a class cast exception from Freemarker when using a
> lookup key that is just a single character:
>  
> Caused by: java.lang.ClassCastException: java.lang.Character cannot be cast to java.lang.String
>         at
> java.lang.String$CaseInsensitiveComparator.compare(String.java:1211)
>         at java.util.TreeMap.getEntryUsingComparator(TreeMap.java:351)
>         at java.util.TreeMap.getEntry(TreeMap.java:322)
>         at java.util.TreeMap.get(TreeMap.java:255)
>         at freemarker.template.SimpleHash.get(SimpleHash.java:203)
>         at freemarker.core.Dot._getAsTemplateModel(Dot.java:76)
>         at
> freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
>         at freemarker.core.Assignment.accept(Assignment.java:90)
>         at freemarker.core.Environment.visit(Environment.java:208)
>         at freemarker.core.MixedContent.accept(MixedContent.java:92)
> ...
>  
> I took a look at the source and I don’t see any way around it
> except using more than one character as my key:
>  
> From SimpleHash.get(String key), line 199:
>  
> if(key.length() == 1) {
>       // just check for Character key if this is a single-character string
>       Character charKey = new Character(key.charAt(0));
>       result = map.get(charKey);
>       if (result == null && !(map.containsKey(key) || map.containsKey(charKey))) {
>             return null;
>       }
>       else {
>             putKey = charKey;
>       }
> }
> else if(!map.containsKey(key)) {
>       return null;
> }
> else {
>       putKey = key;
> }
>  
> It looks like TreeMap is being used as the implementation of the
> map field in SimpleHash and when TreeMap runs through the tree
> trying to find the right value, it tries to compare another key
> stored as a String to this Character object that Freemarker is
> requesting.  Any idea why the key is being converted to a Character
> and is there any way around it?  I don’t see the same thing
> happening on SimpleHash.put() so I find it really strange that it would happen on get().
>  
> Thanks,
> Cameron
>  
> Cameron Hinkle  |  Senior Application Engineer  |  Nike DCIT  | 
> 503.532.3075  |  7. Evolve Immediately |
>  


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