package?com.mrwang.calculator;

import?java.util.Iterator;
import?java.util.Scanner;
import?java.util.Stack;

public?class?Calculator?{
	//定義操作符常量
	private?final?static?char?ADD?=?‘+‘;
	private?final?static?char?SUBTRACT?=?‘-‘;
	private?final?static?char?MULTIPLY?=?‘*‘;
	private?final?static?char?DIVIDE?=?‘/‘;
	public?static?void?main（String[]?args）?{
		//?獲取輸入的值??
		//?“3+（1*2）-（5+2）“
		Scanner?in?=?new?Scanner（System.in）;
		System.out.println（“請輸入一個數學表達式：“）;
		String?expression?=?in.nextLine（）;
		String?postfix?=?Calculator.infixToPostfix（expression）;
		System.out.println（postfix）;
		System.out.println（Calculator.calculator（postfix））;
	}

	/**
	?*?該方法用來將中綴表達式（數學表達式）轉為后綴表達式（逆波蘭表達式）
	?*?Infix?to?Postfix?
	?*?http://blog.fishc.com/2093.html/2#prettyPhoto?中綴表達式轉后綴表達式
	?*?http://blog.tpircsboy.com/acm/poj-1686/??后綴表達式求值
	?*?http://www.aijava.cn/13197.html
	?*?@param?infixPression
	?*?@return
	?*/
	public?static?String?infixToPostfix（String?infixexpression）{
		Stack?S1?=?new?Stack（）;//?運算符棧
		Stack?S2?=?new?Stack（）;//?表達式棧
		int?len?=?infixexpression.length（）;?//?中綴表達式的長度
		int?index?=?0;
		while（index?			char?c?=?infixexpression.charAt（index）;
			switch（c）{
			case?‘（‘:
				S1.push（c）;
				break;
			case?‘）‘:
				while（S1.peek（）?!=?‘（‘）?{
					S2.push（S1.pop（））;
				}
				S1.pop（）;
				break;
			case?ADD:
			case?SUBTRACT:
				while（!S1.empty（）?&&?S1.peek（）?!=?‘（‘）?{
					S2.push（S1.pop（））;
				}
				S1.push（c）;
				break;
			case?MULTIPLY:
			case?DIVIDE:
				w