code: public LabelAlphabet buildLabelAlphabet(String name)	{
  		IAlphabet alphabet = null;
  		if (!maps.containsKey(name))	{
  			maps.put(name, new LabelAlphabet());
  			alphabet = maps.get(name);
  		}else	{
  			alphabet = maps.get(name);
  			if (!(alphabet instanceof LabelAlphabet))	{
  				throw new ClassCastException();
  			}
  		}
  		return (LabelAlphabet) alphabet;
  	}
docs: 构造类别词典
  @param name 词典名称
  @return 类别词典