四则运算(小清新)
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html > <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>你真棒</title> <style type="text/css"> body { background-image: url(start.jpg); background-size:1200px 700px; text-align:center; } </style> </head> <body> <div style="text-align: center; font-family: 微软雅黑; font-size: 50px; color: #C03; "><strong><em>四则运算</em></strong></div> <div style="text-align: center; font-family: 微软雅黑; font-size: 15px; color: #C03; "><strong><em>Welcome To User The System</em></strong></div> <br/> <form name="form1" method="post" action="arithmetic.jsp" > <blockquote> <blockquote> <blockquote> <blockquote> <blockquote> <blockquote> <blockquote> <blockquote> <blockquote> <blockquote> <div style="color: #C03"> <p>选择题目类型: <input name="elementNum" value="2" type="radio" />2元运算 <input name="elementNum" value="3" type="radio" checked="checked"/>3元运算<br><br> <strong>题目数量: <select name="count"> <option>10</option> <option>20</option> <option>30</option> <option>40</option> <option>50</option> <option>60</option> </select> <br /><br /> 限定时间: <select name="timelimit"> <option>1</option> <option>2</option> <option>3</option> <option>4</option> <option>5</option> <option>6</option> </select> 分钟 <br /> <input name="" type="submit" value="开始答题" style="margin:0 auto;display:block;" /> </strong> </p> </div> </blockquote> </blockquote> </blockquote> </blockquote> </blockquote> </blockquote> </blockquote> </blockquote> </blockquote> </blockquote> </form> </body> </html>
public class Arithmetic { public static void main(String args[]){ System.out.println(arithmetic("2.2+((3+4)*2-22)/2*3.2")); } public static double arithmetic(String exp){ String result = parseExp(exp).replaceAll("[\\[\\]]", ""); return Double.parseDouble(result); } /** * 解析计算四则运算表达式,例:2+((3+4)*2-22)/2*3 */ public static String parseExp(String expression){ //String numberReg="^((?!0)\\d+(\\.\\d+(?<!0))?)|(0\\.\\d+(?<!0))$"; expression=expression.replaceAll("\\s+", "").replaceAll("^\\((.+)\\)$", "$1"); String checkExp="\\d"; String minExp="^((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\]))[\\+\\-\\*\\/]((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\]))$"; //最小表达式计算 if(expression.matches(minExp)){ String result=calculate(expression); return Double.parseDouble(result)>=0?result:"["+result+"]"; } //计算不带括号的四则运算 String noParentheses="^[^\\(\\)]+$"; String priorOperatorExp="(((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\]))[\\*\\/]((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\])))"; String operatorExp="(((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\]))[\\+\\-]((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\])))"; if(expression.matches(noParentheses)){ Pattern patt=Pattern.compile(priorOperatorExp); Matcher mat=patt.matcher(expression); if(mat.find()){ String tempMinExp=mat.group(); expression=expression.replaceFirst(priorOperatorExp, parseExp(tempMinExp)); }else{ patt=Pattern.compile(operatorExp); mat=patt.matcher(expression); if(mat.find()){ String tempMinExp=mat.group(); expression=expression.replaceFirst(operatorExp, parseExp(tempMinExp)); } } return parseExp(expression); } //计算带括号的四则运算 String minParentheses="\\([^\\(\\)]+\\)"; Pattern patt=Pattern.compile(minParentheses); Matcher mat=patt.matcher(expression); if(mat.find()){ String tempMinExp=mat.group(); expression=expression.replaceFirst(minParentheses, parseExp(tempMinExp)); } return parseExp(expression); } /** * 计算最小单位四则运算表达式(两个数字) * @param exp * @return */ public static String calculate(String exp){ exp=exp.replaceAll("[\\[\\]]", ""); String number[]=exp.replaceFirst("(\\d)[\\+\\-\\*\\/]", "$1,").split(","); BigDecimal number1=new BigDecimal(number[0]); BigDecimal number2=new BigDecimal(number[1]); BigDecimal result=null; String operator=exp.replaceFirst("^.*\\d([\\+\\-\\*\\/]).+$", "$1"); if("+".equals(operator)){ result=number1.add(number2); }else if("-".equals(operator)){ result=number1.subtract(number2); }else if("*".equals(operator)){ result=number1.multiply(number2); }else if("/".equals(operator)){ result=number1.divide(number2); } return result!=null?result.toString():null; } }