Java使用逆波兰表达式算法制作的表达式计算器，波兰表达式计算器,package com.

Java使用逆波兰表达式算法制作的表达式计算器，波兰表达式计算器,package com.

package com.infogrid.g2b;   import java.util.HashMap;   import java.util.Map;   public class Op {       private static final Map<String,Integer> ops = new HashMap<String, Integer>();       static{           ops.put("+",10);           ops.put("-",10);           ops.put("*",20);           ops.put("/",20);           ops.put("%",20);           ops.put("(",100);           ops.put(")",100);       }       public static boolean isSign(String sign1){           Integer s = ops.get(sign1);           if(s==null)               return false;           else              return true;       }       public static int compare(String sign1,String sign2){           Integer p1 = ops.get(sign1);           Integer p2 = ops.get(sign2);           if(p1==null)               throw new IllegalArgumentException("符号："+sign1+"不存在！");           if(p2==null)               throw new IllegalArgumentException("符号："+sign2+"不存在！");           return p1-p2;       }       public static Object cal(Object x,Object y,String sign){           Double a=0.0,b=0.0;           a = Double.valueOf(x+"");           b = Double.valueOf(y+"");           if(sign.equals("+"))               return a+b;           if(sign.equals("-"))               return a-b;           if(sign.equals("*"))               return a*b;           if(sign.equals("/"))               return a/b;           if(sign.equals("%"))               return a%b;           throw new IllegalArgumentException("操作符不合法！");       }   }  package com.infogrid.g2b;   import java.util.ArrayList;   import java.util.List;   import java.util.Stack;   public class Calculator {       private List<String> list = new ArrayList<String>();       private Stack<String> stack = new Stack<String>();       private List<String> resolveExpr(String exp){              String opert=exp.replaceAll("\\d*\\.\\d+?", "");           List<String> list=new ArrayList<String>();              int pidx=-1;              for(int i=0;i<opert.length();i++){                  String p=opert.substring(i, i+1);                  pidx=exp.indexOf(p);                  if(exp.substring(0,pidx).trim().length()!=0){                      list.add(exp.substring(0, pidx));                  }                  list.add(exp.substring(pidx, pidx+1));                  exp=exp.substring(pidx+1);              }              if(exp.length()>0){                  list.add(exp);              }              return list;          }          private void dealSign(String s){           if(stack.size()==0){               stack.push(s);               return;           }           String ps = stack.pop();           if(Op.compare(s, ps)>0||ps.equals("(")){               if(s.equals(")")){                   list.add(ps);                   while(stack.size()>0){                       ps = stack.pop();                       if(ps.equals("("))                           break;                       list.add(ps);                   }               }else{                   stack.push(ps);                   stack.push(s);               }           }else{               list.add(ps);               dealSign(s);           }       }       private void dealVar(String s){           list.add(s);       }       private Double getResult(){           for(String s:list){               if(!Op.isSign(s)){                   stack.push(s);                   continue;               }               Object a = 0,b = 0;               if(stack.size()>0)                   b = stack.pop();               if(stack.size()>0)                   a = stack.pop();               stack.push(Op.cal(a, b, s)+"");           }           return Double.valueOf(stack.pop());       }       public Double calculate(String expression){           List<String> ss = resolveExpr(expression);           for(String s:ss){               if(Op.isSign(s)){                   dealSign(s);               }else{                   dealVar(s);               }           }           while(stack.size()>0){               list.add(stack.pop());           }           System.out.println(list);           return getResult();       }       public static void main(String[] args) {           System.out.println(new Calculator().calculate("1.5+2.1+((4/2)-6/((2+1)*2))+6%4"));       }   }