Compare operator

Question

I am trying to compare two operators.
The operators are: + - * / ^
They have all different priority
^ = 3
* = 2
/ = 2
+ = 1
- = 1
How can I compare a character '*' with
a character '+' of which one has the
highest priority?

Answer 1

I thought this really would work, but
surely I have missed something.
This is my code:
import java.util.*;
import javax.swing.*;
public class InfixToPostfix {
     public static void main(String[] args) {
          Object slutt            = "#";
          String infixStr      = JOptionPane.showInputDialog("Tast inn infix-uttrykket: ");
          infixStr              += slutt;
          String postfixStr     = "";
          System.out.println("Infix: "+infixStr);
          Stack stack = new Stack();
          stack.add(slutt);
          System.out.println ("Stack is empty: "+stack.empty ()+ ", Stack: " + stack);
          Map <String, Integer> priorities = new HashMap<String, Integer>();
          priorities.put("^", 3);
          priorities.put("*", 2);
          priorities.put("*", 2);
          priorities.put("+", 1);
          priorities.put("-", 1);
          priorities.put("#", 0);
          //String op = "+";
          Object c;
          String stackOp;
          String infixOp;
          int infixPri;
          int stackPri;
          for (int i=0; i<infixStr.length(); i++) {
               c = infixStr.charAt(i);
               infixOp= c.toString();
               infixPri = priorities.get(infixOp);
               System.out.println("A: "+infixPri+infixOp);
               if (infixOp == "+" || infixOp == "-" || infixOp == "*" || infixOp == "/" || infixOp == "^") {
                    if (stack.empty()) {
                         stack.push(String.valueOf(c));
                    else {
                         while (!stack.empty()) {
                              stackOp = (String) stack.pop();
                              stackPri = priorities.get(stackOp);
                              if (stackPri >= infixPri) {
                                   postfixStr += stackOp;
                              else stack.push(String.valueOf(c));
               else if (c == "#") {
                    System.out.println("Postfix: "+ postfixStr);
                    System.exit(0);
               else {
                    postfixStr += c;
}At these lines: "stack.push(String.valueOf(c));"
I get this message -->
Type safety: The method push(Object) belongs to the raw type Stack. References to generic type
Stack<E> should be parameterized