Logical infix expression to postfix error

Question

Hi,
I've got a program which takes input at command line as an infix expressions and then aims to convert it to postfix for later evaluation . I carry this out using two stacks. My coding for this to happen is below( only parts i felt needed):
private String postfix = "";
    private static Stack<Character> operatorStack = new Stack<Character>();
    private static Stack<Character> operandStack = new Stack<Character>();
            userEntry.trim();
            char[] temp = userEntry.toCharArray();
            for (int i = 0 ; i < temp.length ; i++) {
                char a = temp;
System.out.println(a);
dump(temp);
if(userEntry.startsWith("end")) {
finished = true;
System.out.println("Thank You for using Calculator");
* dump. Places the input into a char array and push each
* char to stack.
* @param temp array of strings to be tokenized and
* pushed ontop of stack
private void dump(char[] temp)
for(char c : temp) {
Character C = new Character(c);
String token;
token = C.toString();
System.out.println("Testing token "+token);
//its a number just add to the postfix string
if (Character.isDigit(C)) {
postfix = postfix + "" + (Integer.parseInt(token));
System.out.println("new infix"+ postfix);
//its an operator so push it to operator stack
else if (token.equals("(")) {
operatorStack.push(C);
System.out.println(operatorStack.peek());
// pop everthing before the ")" until you hit an "(" , this will be the operands
else if (token.equals(")")) {
while ((operatorStack.peek()).charValue() != '(') {
char ch = operatorStack.pop();
postfix = postfix + " " + ch;
System.out.println(operatorStack.empty()+"operator stack is empty");
System.out.println("new postfix 2 "+postfix);
System.out.println(operatorStack.pop()+"jus kicked somthin off");
else if (token.equals(" ")){}
//find the order of operators and put this in to the postfix script, the operators +-,/,- never make it on to the stack
else {               
System.out.println(operatorStack.empty()+"operator stack is empty");
System.out.println(C);
while (!(operatorStack.empty()) && !((operatorStack.peek()).equals('('))
&& ((setPrecedence(C)) <= (setPrecedence((operatorStack.peek()).charValue())))) {
System.out.println("precedence test"+operatorStack.peek());
operatorStack.push(C);
postfix = postfix + " " + operatorStack.pop();
System.out.println("just pushed operator");
while (!operatorStack.empty()) {
postfix = postfix + " " + operatorStack.pop();
System.out.println("last postfix :"+postfix);
public int setPrecedence(char x)
if (x == '+'|| x == '-') {
return 1;
if (x == '*' || x == '/' || x == '%') {
return 2;
return 0;
}if i was to enter at the command line ( 2 + 4 ) * 3 ( must have spaces)
instead of the postfix conversion being "24+3* it results in "243".
I've got various print statement in my code but  still can seem to figure out what am doing wrong. I believe the problem lies in my else block of statements.
Example of entering an expression result :
( 2 * 4 ) * 3
2
4
3
Testing token (
Testing token 
Testing token 2
new infix
Testing token 
Testing token *
falseoperator stack is empty
Testing token 
Testing token 4
new infix24
Testing token 
Testing token )
falseoperator stack is empty
new postfix 2 24
(jus kicked somthin off
Testing token 
Testing token *
trueoperator stack is empty
Testing token 
Testing token 3
new infix243
last postfix :243
If you can see any reason why its producing this instead of the desired or any thing you disapprove of i would be  greatful if you would kindly say so.
Thanks alot.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

Answer 1

* CORRECTED CODING INDENTION sorry* hopefully a little clearer.
Hi,
I've got a program which takes input at command line as an infix expressions and then aims to convert it to postfix for later evaluation . I carry this out using two stacks. My coding for this to happen is below( only parts i felt needed):
private String postfix = "";
private static Stack<Character> operatorStack = new Stack<Character>();
private static Stack<Character> operandStack = new Stack<Character>();
            userEntry.trim();
            char[] temp = userEntry.toCharArray();
            for (int i = 0 ; i < temp.length ; i++) {
                char a = temp;
System.out.println(a);
dump(temp);
if (userEntry.startsWith("end")) {
finished = true;
System.out.println("Thank You for using Calculator");
* dump. Places the input into a char array and push each
* char to stack.
* @param temp array of strings to be tokenized and
* pushed ontop of stack
private void dump(char[] temp)
for(char c : temp) {
Character C = new Character(c);
String token;
token = C.toString();
System.out.println("Testing token "+token);
//its a number just add to the postfix string
if (Character.isDigit(C)) {
postfix = postfix + "" + (Integer.parseInt(token));
System.out.println("new infix"+ postfix);
//its an operator so push it to operator stack
else if (token.equals("(")) {
operatorStack.push(C);
System.out.println(operatorStack.peek());
// pop everthing before the ")" until you hit an "(" , this will be the operands
else if (token.equals(")")) {
while ((operatorStack.peek()).charValue() != '(') {
char ch = operatorStack.pop();
postfix = postfix + " " + ch;
System.out.println(operatorStack.empty()+"operator stack is empty");
System.out.println("new postfix 2 "+postfix);
System.out.println(operatorStack.pop()+"jus kicked somthin off");
else if (token.equals(" ")) {
//do nothing
//find the order of operators and put this in to the postfix script, the operators +-,/,- never make it on to the stack
else {               
System.out.println(operatorStack.empty()+"operator stack is empty");
System.out.println(C);
while (!(operatorStack.empty()) && !((operatorStack.peek()).equals('('))
&& ((setPrecedence(C)) <= (setPrecedence((operatorStack.peek()).charValue())))) {
System.out.println("precedence test"+operatorStack.peek());
operatorStack.push(C);
postfix = postfix + " " + operatorStack.pop();
System.out.println("just pushed operator");
while (!operatorStack.empty()) {
postfix = postfix + " " + operatorStack.pop();
System.out.println("last postfix :"+postfix);
public int setPrecedence(char x)
if (x == '+'|| x == '-') {
return 1;
if (x == '*' || x == '/' || x == '%') {
return 2;
return 0;
}if i was to enter at the command line ( 2 + 4 ) * 3 ( must have spaces)
instead of the postfix conversion being "24+3* it results in "243".
I've got various print statement in my code but still can seem to figure out what am doing wrong. I believe the problem lies in my else block of statements.
Example of entering an expression result :
( 2 * 4 ) * 3
2
4
3
Testing token (
Testing token
Testing token 2
new infix
Testing token
Testing token *
falseoperator stack is empty
Testing token
Testing token 4
new infix24
Testing token
Testing token )
falseoperator stack is empty
new postfix 2 24
(jus kicked somthin off
Testing token
Testing token *
trueoperator stack is empty
Testing token
Testing token 3
new infix243
last postfix :243
If you can see any reason why its producing this instead of the desired or any thing you disapprove of i would be greatful if you would kindly say so.
Thanks alot.