java 实现的公式计算
发个我写的计算公式代码：
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package org.yangzc.math;import java.util.Stack;import java.util.regex.Matcher;import java.util.regex.Pattern;/** * 数据计算公式 * @author yangzc * */public class MathEval {public static char PLUS = '+';public static char MINUS = '-';public static char MULTI = '*';public static char DEVIDE = '/';public static char BRACKET_LEFT = '(';public static char BRACKET_RIGHT = ')';/** * 计算带小括号的公式 * @param line * @return */public static double eval(String line){while(line.indexOf(BRACKET_LEFT) != -1){Pattern pattern = Pattern.compile("\\(([^\\(\\)]*?)\\)");Matcher matcher = pattern.matcher(line);while(matcher.find()){double result = simpleEval(matcher.group(1));line = line.replace(matcher.group(), result+"");}}return simpleEval(line);}/** * 计算不带括号的公式 * @param line * @return */@SuppressWarnings("unchecked")public static double simpleEval(String line){Stack<Double> valueStack = new Stack<Double>();//保存值的堆栈Stack<Character> markStack = new Stack<Character>();//保存符号的堆栈char ch[] = line.toCharArray();//计算乘除操作String tmpValue = "";boolean isOper = false;for(int i=0; i< ch.length; i++){if( ch[i] == PLUS || ch[i] == MINUS || ch[i] == MULTI || ch[i] == DEVIDE) {double dv = Double.valueOf(tmpValue).doubleValue();if(isOper){double dv1 = valueStack.pop();char op = markStack.pop();double result = simpleTwoEval(op, dv1, dv);dv = result;}valueStack.push(dv);markStack.push(ch[i]);tmpValue = "";isOper = false;if( ch[i] == MULTI || ch[i] == DEVIDE )isOper = true;}else{tmpValue += ch[i] + "";if(i == ch.length -1){double dv = Double.valueOf(tmpValue).doubleValue();if(isOper){double dv1 = valueStack.pop();char op = markStack.pop();double result = simpleTwoEval(op, dv1, dv);dv = result;}valueStack.push(dv);}}}//for(int i=0; i< valueStack.size(); i++){//System.out.println(valueStack.get(i));//}//for(int i=0; i< markStack.size(); i++){//System.out.println(markStack.get(i));//}//计算加减操作valueStack = (Stack<Double>) reverseStack(valueStack);markStack = (Stack<Character>) reverseStack(markStack);while(valueStack.size() > 1){double v1 = valueStack.pop();double v2 = valueStack.pop();char op = markStack.pop();double result = simpleTwoEval(op, v1, v2);valueStack.push(result);}return valueStack.get(0);}/** * 把整个堆栈翻转 * @param stack * @return */@SuppressWarnings("unchecked")private static Stack<?> reverseStack(Stack<?> stack){Stack reverse = new Stack();int stackSize = stack.size();for(int i=0; i< stackSize; i++){reverse.push(stack.pop());}return reverse;}/** * 只计算简单的两个数结果 * @param op * @param value1 * @param value2 * @return */private static double simpleTwoEval(char op, double value1, double value2){if(op == PLUS){return value1 + value2;}else if(op == MINUS){return value1 - value2;}else if(op == MULTI){return value1 * value2;}else if(op == DEVIDE){return value1 / value2;}return 0;}public static void main(String[] args) {double result = MathEval.eval("1+(2*(3+2))-6+(3/2)+4/2");System.out.println();System.out.println(result);}}?