文本四则运算解析工具与浮点数小数精度保留工具

我会带着你远行 2022-06-13 12:53 202阅读 0赞

1、文本四则公式解析工具类：

package org.nercita.ntp.summary.util;
    import java.util.ArrayList;
    import java.util.LinkedList;
    /**
     * @author zhangwenchao
     * @since 2017-07-6
     * 公式解析计算的工具类
     */
    public class FormulaCalculatorUtil {
     
     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(FormulaCalculatorUtil.getResult("3-(4*5)+5")); 
      System.out.println(FormulaCalculatorUtil.getResult("7/2-(-4)"));   
      System.out.println(FormulaCalculatorUtil.getResult("1287763200000-1276272000000")/(3600*24*1000));
     }
     
    }

2、浮点精度保留工具类：

package org.nercita.ntp.summary.util;
    import java.math.RoundingMode;
    import java.text.DecimalFormat;
    /**
     * @author zhangwenchao
     * 小数点 精度的工具类
     */ 
    public class NumberPrecisionUtil {
      
     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); 
      f.setRoundingMode(RoundingMode.HALF_UP); //四舍五入
      String s = f.format(x).toString(); 
      return s;     
     }
     
     
    }