java解析四则运算表达式

java的复杂四则运算，暂时先实现四则运算表达式的解析。存储入数据栈、运算符栈。
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 1 package com.app;
 2 
 3 import java.util.Stack;
 4 
 5 public class calcapp {
 6     private Stack<Double>         s1;
 7     private Stack<Character>    s2;
 8     
 9     public calcapp(){
10         s1 = new Stack<Double>();
11         s2 = new Stack<Character>();
12     }
13     
14     public void calcformula(String input){
15         
16         //先实现对四则运算表达式的解析
17         char temp;
18         StringBuffer sv = new StringBuffer();
19         Double       dv = 0.0;
20         
21         for(int i = 0; i < input.length(); i++){
22             temp = input.charAt(i);
23             
24             if(('=' == temp)
25                 && (0 != sv.length())){
26                 dv = Double.parseDouble(sv.toString());
27                 s1.push(dv);
28             }
29             
30             if(' ' == temp){
31                 continue;
32             }
33             
34             if(isOperator(temp)){
35                 if(0 != sv.length()){
36                     dv = Double.parseDouble(sv.toString());
37                     sv.setLength(0);    
38                     s1.push(dv);
39                     dv = 0.0;
40                 }
41                 
42                 s2.push(temp);    
43             }else{
44                 sv.append(temp);
45             }        
46         }// end of for(int i = 0; i < input.length(); i++){
47         
48 //show the Operataror
49         System.out.println("number as following:");
50         while(!s1.empty()){
51             System.out.println(s1.pop());
52         }
53         System.out.println("Operator as following:");
54         while(!s2.empty()){
55             System.out.println(s2.pop());
56         }
57     }
58     
59 
60     public boolean isOperator(char temp){
61         if(('(' == temp)
62             ||(')' == temp)
63             ||('+' == temp)
64             ||('-' == temp)
65             ||('*' == temp)
66             ||('/' == temp)){
67             return true;
68         }
69         
70         
71         return false;
72     }
73 }