class Stuff
{
	/**
	 * "Cleans up" a string by removing all leading and trailing characters
	 * that are not letters.
	 * @param aString the string to be cleaned up
	 * @return the cleaned up version of parameter aString, or a null
	 * pointer if the string contains no letters at all
	 */
	public static String cleanUp(String aString)
	{
		int pos = aString.length() - 1 ;	// start at position of last char
		
		// while current char is not a letter
		while ( ! Character.isLetter(aString.charAt(pos)) )
		{
			pos-- ;				// move to previous char
			
			if (pos == -1)		// if string had no letters...
			  return null ;		// ...return null reference
		}
		// loop postcondition: pos is position of last letter in aString
		
		// remove nonletters from end of aString
		aString = aString.substring(0, pos+1) ;
				
		pos = 0 ;			// start at position of first character
		
		while ( ! Character.isLetter(aString.charAt(pos)) )
		{
			pos++ ;			// move to next char
		}
		// loop postcondition: pos is position of first letter in aString
		
		// remove nonletters from start of aString
		aString = aString.substring(pos) ;
		
		return aString ;
	}
}