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。

package com.app;

import java.util.Stack;

public class calcapp {
    private Stack<Double>         s1;
    private Stack<Character>    s2;
    
    public calcapp(){
        s1 = new Stack<Double>();
        s2 = new Stack<Character>();
    }
    
    public void calcformula(String input){
        
        //先实现对四则运算表达式的解析
        char temp;
        StringBuffer sv = new StringBuffer();
        Double       dv = 0.0;
        
        for(int i = 0; i < input.length(); i++){
            temp = input.charAt(i);
            
            if(('=' == temp)
                && (0 != sv.length())){
                dv = Double.parseDouble(sv.toString());
                s1.push(dv);
            }
            
            if(' ' == temp){
                continue;
            }
            
            if(isOperator(temp)){
                if(0 != sv.length()){
                    dv = Double.parseDouble(sv.toString());
                    sv.setLength(0);    
                    s1.push(dv);
                    dv = 0.0;
                }
                
                s2.push(temp);    
            }else{
                sv.append(temp);
            }        
        }// end of for(int i = 0; i < input.length(); i++){
        
//show the Operataror
        System.out.println("number as following:");
        while(!s1.empty()){
            System.out.println(s1.pop());
        }
        System.out.println("Operator as following:");
        while(!s2.empty()){
            System.out.println(s2.pop());
        }
    }
    

    public boolean isOperator(char temp){
        if(('(' == temp)
            ||(')' == temp)
            ||('+' == temp)
            ||('-' == temp)
            ||('*' == temp)
            ||('/' == temp)){
            return true;
        }
        
        
        return false;
    }
}