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ClassCastException

Hunter McMillen
Ranch Hand

Joined: Mar 13, 2009
Posts: 492

Hey everyone,

I'm working on creating a symbol table for a parser I am writing and I am using a hashtable to implement my symbol table. I'm running into some trouble when I try to print out the values in my table. Here's what I'm doing:


here is my driver:



Any help would be great.
Thanks,
Hunter


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Bear Bibeault
Author and ninkuma
Marshal

Joined: Jan 10, 2002
Posts: 60078
    
  65

And the problem?


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Seetharaman Venkatasamy
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Joined: Jan 28, 2008
Posts: 5575

Hunter McMillen wrote:



element = (String)iterator.nextElement(); it gives you a value element of Hashtable which is SymbolTableEntry . SymbolTableEntry is not a String , but you are trying to cast to String, so Obviously you get *ClassCastException*

hth
Jesper de Jong
Java Cowboy
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Joined: Aug 16, 2005
Posts: 13884
    
  10

Note that classes Hashtable and Enumeration are legacy collection classes. They have been (more or less) replaced by the collections framework in Java 1.2 (a long time ago!). See Sun's tutorial about collections for more information.

Use HashMap instead of Hashtable and Iterator instead of Enumeration.

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Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19556
    
  16

And iterate over the entrySet() instead of iterating over the keySet(), then retrieving the elements using get:


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