java实现字符串四则运算公式解析工具类的方法

java实现字符串四则运算公式解析工具类的方法

项目中用到用户定义运算公式进行就算的需求，这样需要进行字符串四则运算解析，下面提供字符串公式四则运算解析fNzXbs与计算工具类，需要的同学可参考。

工具类如下：FormulaCalculator.java：

package org.nercita.bcp.record.util;

import java.util.ArrayList;

import java.util.LinkedList;

/**

* @author zhangwenchao

* @since 2016-08-26

* 公式计算的工具类

*/

public class FormulaCalculator {

private static boolean isRightFormat = true;

public static double getResult(String formula){

double returnValue = 0;

try{

returnValue = doAnalysis(formula);

}catch(NumberFormatException nfe){

System.out.println("公式格式有误，请检查:" + formula);

}catch(Exception e){

e.printStackTrace();

}

if(!isRightFormat){

System.out.println("公式格式有误，请检查:" + formula);

}

return returnValue;

}

private static double doAnalysis(String formula){

double returnValue = 0;

LinkedList stack = new LinkedList();

int curPos = 0;

String beforePart = "";

String afterPart = "";

String calculator = "";

isRightFormat = true;

while(isRightFormat&&(formula.indexOf('(') >= 0||formula.indexOf(')') >= 0)){

curPos = 0;

for(char s : formula.toCharArray()){

if(s == '('){

stack.add(curPos);

}else if(s == ')'){

if(stack.size() > 0){

beforePart = formula.substring(0, stack.getLast());

afterPart = formula.substring(curPos + 1);

calculator = formula.substring(stack.getLast() + 1, curPos);

formula = beforePart + doCalculation(calculator) + afterPart;

stack.clear();

break;

}else{

System.out.println("有未关闭的右括号！");

isRightFormat = false;

}

}

curPos++;

}

if(stack.size() > 0){

System.out.println("有未关闭的左括号！");

break;

}

}

if(isRightFormat){

returnValue = doCalculation(formula);

}

return retufNzXbsrnValue;

}

private static double doCalculation(String formula) {

ArrayList values = new ArrayList();

ArrayList operators = new ArrayList();

int curPos = 0;

int prePos = 0;

int minus = 0;

for (char s : formula.http://toCharArray()) {

if ((s == '+' || s == '-' || s == '*' || s == '/') && minus !=0 && minus !=2) {

values.add(Double.parseDofNzXbsuble(formula.substring(prePos, curPos).trim()));

operators.add("" + s);

prePos = curPos + 1;

minus = minus +1;

}else{

minus =1;

}

curPos++;

}

values.add(Double.parseDouble(formula.substring(prePos).trim()));

char op;

for (curPos = 0; curPos <= operators.size() - 1; curPos++) {

op = operators.get(curPos).charAt(0);

switch (op) {

case '*':

values.add(curPos, values.get(curPos) * values.get(curPos + 1));

values.remove(curPos + 1);

values.remove(curPos + 1);

operators.remove(curPos);

curPos = -1;

break;

case '/':

values.add(curPos, values.get(curPos) / values.get(curPos + 1));

values.remove(curPos + 1);

values.remove(curPos + 1);

operators.remove(curPos);

curPos = -1;

break;

}

}

for (curPos = 0; curPos <= operators.size() - 1; curPos++) {

op = operators.get(curPos).charAt(0);

switch (op) {

case '+':

values.add(curPos, values.get(curPos) + values.get(curPos + 1));

values.remove(curPos + 1);

values.remove(curPos + 1);

operators.remove(curPos);

curPos = -1;

break;

case '-':

values.add(curPos, values.get(curPos) - values.get(curPos + 1));

values.remove(curPos + 1);

values.remove(curPos + 1);

operators.remove(curPos);

curPos = -1;

break;

}

}

return values.get(0).doubleValue();

}

public static void main(String[] args) {

System.out.println(FormulaCalculator.getResult("3-(4*5)+5"));

System.out.println(FormulaCalculator.getResult("7/2-(-4)"));

System.out.println(FormulaCalculator.getResult("1287763200000-1276272000000")/(3600*24*1000));

}

}

支持四则运算，同时支持负数解析。

另附，小数数据保留位数工具类，SetNumberPrecision.java

package org.nercita.bcp.record.util;

import java.text.DecimalFormat;

/**

* @author zhangwenchao

* 小数点 精度的工具类

*/

public class SetNumberPrecision {

public static String setNumberPrecision(double x,int Number){

String p="#########0";

if(Number==0){

p="#########0";

}else{

p="#########0.";

for(int i=0;i

p=p+"0";

}

}

DecimalFormat f = new DecimalFormat(p);

String s = f.format(x).toString();

return s;

}

}

p=p+"0";

}

}

DecimalFormat f = new DecimalFormat(p);

String s = f.format(x).toString();

return s;

}

}

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