java实现字符串四则运算公式解析工具类的方法

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<Integer> stack = new LinkedList<Integer>(); 		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 returnValue; 	} 		private static double doCalculation(String formula) { 		ArrayList<Double> values = new ArrayList<Double>(); 		ArrayList<String> operators = new ArrayList<String>(); 		int curPos = 0; 		int prePos = 0;		int minus = 0;				for (char s : formula.toCharArray()) { 			 if ((s == '+' || s == '-' || s == '*' || s == '/') && minus !=0 && minus !=2) { 								 			 				 values.add(Double.parseDouble(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));	}	}

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<Number;i++){//for的巧妙运用		   				p=p+"0"; 		  			}		 		}		  		DecimalFormat f = new DecimalFormat(p); 		  		String s = f.format(x).toString(); 		  		return s;		 	}	}