title: How to extract letter words only from an arbitrary input file
body: <p>I'm writing a spell checker, and I have to extract only word (constructed out of letter). I'm having trouble using multiple delimiters. Java documentation specifies the use of several delimiters, but I have troubles including every printing character that is not a letter.</p>
  
  <pre><code>in_file.useDelimiter("., !?/@#$%^&amp;*(){}[]&lt;&gt;\\\"'");
  </code></pre>
  
  <p>in this case - run time  </p>
  
  <pre><code>    Exception in thread "main" java.util.regex.PatternSyntaxException:
   Unclosed character class near index 35
  </code></pre>
  
  <p>I tried using pattern such as </p>
  
  <pre><code>("\s+,|\s+\?|""|\s:|\s;|\{}|\s[|[]|\s!"); 
  </code></pre>
  
  <p>run time - </p>
  
  <pre><code>    Exception in thread "main" java.util.regex.PatternSyntaxException:
   Illegal repetition 
  </code></pre>
  
  <p>I'm aware of tokenizer but we are restricted to use scanner.</p>