@Override
	public ResultMessage updGoodsClass(GoodsClassPO goodsClassPO) {
		gcIter = goodsClassList.iterator();
		GoodsClassPO gcp;
		GoodsClassPO toBeUpd = null;
		boolean conflict = false;
		while(gcIter.hasNext()) {
			gcp = gcIter.next();
			if(goodsClassPO.Num == gcp.Num) {
				toBeUpd = gcp;
			}
			conflict = conflict || (goodsClassPO.goodsClassName.equals(gcp.goodsClassName));
			
		}
		
		if(!conflict && (toBeUpd != null)) {
			toBeUpd.goodsClassName = goodsClassPO.goodsClassName;
			writeFile();
			return ResultMessage.update_success;
		}
		else {
			return ResultMessage.update_failure;
		}
	}