主类Main2

/**
	 * 基本计算
	 * @param x
	 * @param y
	 * @param operator
	 * @return
	 */
	public static double account(double x, double y, String operator)
	{
		if(operator.equals(Operator.ADD))
		{
			return x + y;
		}
		else if(operator.equals(Operator.MINUS))
		{
			return x - y;
		}
		else if(operator.equals(Operator.MULTIPLY))
		{
			return x * y;
		}
		else if(operator.equals(Operator.DIVIDE))
		{
			return x / y;
		}
		return 0;
	}

	public static void main(String[] args)
	{
		String formula = "(1 + 3 * 2) / {[2 * ( 1 + 3)] - 3} - (3 * 2)";
		
		//小中大括号正则匹配
		String[] gh = {"\\(.*?\\)", "\\[.*?\\]", "\\{.*?\\}"};
		
		//先计算小括号，再计算中括号，大括号
		for(int i = 0; i < gh.length; i++)
		{
			Pattern pattern = Pattern.compile(gh[i]);
			Matcher matcher = pattern.matcher(formula);
			while(matcher.find())
			{
				//获得括号公式
				String f = matcher.group();
				
				//计算括号内公式
				double value = accountFormula(f.replace(" ", ""), true);
				
				//将计算的值放入原公式
				formula = formula.replace(f, value + "");
			}
			System.out.println(formula);
		}
		
		//计算最后剩余公式
		double value = accountFormula(formula, false);
		System.out.println("结果：" + value);
	}
	
	/**
	 * 计算不包含括号的公式
	 * @param formula   公式
	 * @param isClearGh 是否去括号
	 * @return
	 */
	public static double accountFormula(String formula, boolean isClearGh)
	{
		if(isClearGh)
		{
			//去括号
			formula = formula.substring(1, formula.length() - 1);
		}
		
		//计算乘除
		formula = accountMultiplyAndDivide(formula);
		
		//计算加减
		double ret = accountMinusAndAdd(formula);
		
		return ret;
	}