Infix to postfix and evaluate: having problems

[aitia]

this the code. i used ECLIPSE to run this.. it has some codes smells that i can't seem to figure out.. can any one help?

[CODE=java]import java.io.*;
import java.util.*;

public class Postfix
{
private static Stack operators = new Stack();
private static Stack operands = new Stack();

public static void main(String argv[]) throws IOException
{
String infix;

//create an input stream object
BufferedReader keyboard = new BufferedReader (new
InputStreamRead er(System.in));

//get input from user
System.out.prin t("\nEnter the algebraic expression in infix: ");
infix = keyboard.readLi ne();

//output as postfix
System.out.prin tln("The expression in postfix is:" + toPostfix(infix ));

//get answer
System.out.prin tln("The answer to the equation is: " + evaluate
(toPostfix(infi x)) + "\n");
}

private static String toPostfix(Strin g infix)
//converts an infix expression to postfix
{
StringTokenizer s = new StringTokenizer (infix);
//divides the input into tokens
String symbol, postfix = "";
while (s.hasMoreToken s())
//while there is input to be read
{
symbol = s.nextToken();
//if it's a number, add it to the string
if (Character.isDi git(symbol.char At(0)))
postfix = postfix + " " + (Integer.parseI nt
(symbol));
else if (symbol.equals( "("))
//push (
{
Character operator = new Character('(');
operators.push( operator);
}
else if (symbol.equals( ")"))
//push everything back to (
{
while (((Character)op erators.peek()) .charValue() != '(')
{
postfix = postfix + " " + operators.pop() ;
}
operators.pop() ;
}
else
//print operators occurring before it that have greater precedence
{
while (!operators.emp ty() && !(operators.pee k()).equals("(" ) && prec(symbol.cha rAt(0)) <= prec(((Characte r)operators.pee k()).charValue( )))
postfix = postfix + " " + operators.pop() ;
Character operator = new Character(symbo l.charAt(0));
operators.push( operator);
}
}
while (!operators.emp ty())
postfix = postfix + " " + operators.pop() ;
return postfix;
}

private static int evaluate(String postfix)
{
StringTokenizer s = new StringTokenizer (postfix);
//divides the input into tokens
int value;
String symbol;
while (s.hasMoreToken s())
{
symbol = s.nextToken();
if (Character.isDi git(symbol.char At(0)))
//if it's a number, push it
{
Integer operand = new Integer(Integer .parseInt(symbo l));
operands.push(o perand);
}
else //if it's an operator, operate on the previous two operands
{
int op2 = ((Integer)opera nds.pop()).intV alue();
int op1 = ((Integer)opera nds.pop()).intV alue();
int result = 0;
switch(symbol.c harAt(0))
{
case '*': {result = op1 * op2; break;}
case '+': {result = op1 + op2; break;}
case '-': {result = op1 - op2; break;}
case '/': {result = op1 / op2; break;}
case '%': {result = op1 % op2; break;}
}
Integer operand = new Integer(result) ;
operands.push(o perand);
}
}
value = ((Integer)opera nds.pop()).intV alue();
return value;
}

private static int prec(char x)
{
if (x == '+' || x == '-')
return 1;
if (x == '*' || x == '/' || x == '%')
return 2;
return 0;
}
}[/CODE]

[samido]

what is the matter with this code ...? what it was suppose to do and not happenign yet, what do you pass as inputs and do you expect as out put...? you didn't ask any questionon this thread and I wonder what is it you want us to do.

Sam Rabophala