スタックインプリメンテーション

/**
	 *                    
	 * @param num     
	 * @param hex   
	 * @return   
	 */
	public static String decimalConvert(int num, int hex){
		if(num < 0 || hex <=1 || hex >10){
			return null;
		}
		if(num == 0 || hex == 10){
			return num + "";
		}
		Stack<String> stack = new Stack<String>();
		while(num != 0){
			stack.push(num % hex + "");
			num = num /hex;
		}
		String result = "";
		while(stack.size() != 0){
			result += stack.pop();
		}
		return result;
	}