Operators ins "Conversion from Inx to RPN (postfix)" Java. NO STACK, ONLY STRING MANIPULATION

Question

I have used a subroutine to prioritize between the operators:

static int  p(char c){
    if ((c=='+') || (c=='-')) {
        return 0;
    }
    else if ((c=='/') || (c=='*')) {
        return 1;
    }
    else {
        return -1;
    } 
}

I have worked on the code a bit. I'm supposed to follow this transformation: transformation. for i=1 to m if c_i is an operand: Transfer c_i to output.

if c_i is a left parentheses: Push c_i to temp.

if c_i is a right parentheses: Pop elements from temp and transfer them to output until a left-parentheses is met. Pop left-parentheses.

if c_i is an operator: Let the top temp element be t. Pop and transfer elements from temp to output until: p(t) < p(c_i) or

t is a left-parentheses or

temp is empty.

Push c_i to temp.

Transfer the remaining elements in temp to output.

Problems: 1- I'm basically stuck how to do continue if the the digit is an operator. I'm stuck with the 3rd and 4th steps in the above list. 2- The part with THE TWO ASTERISKS is where I have no idea what to do!

The program should convert infix to postfix. From ((3 + 5 1)=8) 14 to 3 5 1 +8 = 14.

THANKS IN ADVANCE!

Remarks and Notation: -The pop operation removes the first element of the string each time it is applied. The top element of a string is the first element of the string. The push operation appends an element in the beginning of the string.

-You can use the methods Integer:parseInt(s) and Character:getNumericV alue(c) to convert a string s and a character c to an integer value, if needed.

-You are not allowed to use data structures other than Strings to manipulate the expressions.

static String infixToPostfix(String infix){
String postfix = "";
infix = readLine();
String temp ="";
char t;




for (int i=0 ; i<infix.length(); i++) {
    t = temp.charAt(0);
    if (infix.charAt(i)  !=')' && infix.charAt(i)!= '(' && infix.charAt(i)!= p(infix.charAt(i)))
        postfix += infix.charAt(i);


    if (infix.charAt(i) == '+') {


        while (  (p('+') <= p(t)) && (t  != '(')  && (!temp.equals("") )  ){ 

        }
        postfix = postfix + temp.charAt(i);
    }


     if (infix.charAt(i) == '-') {
    while (  (p('-') <= p(t)) && (t  != '(')  && (!temp.equals("") )  ){ 
        postfix = postfix + temp.charAt(i);


        }

    }

    else  if (infix.charAt(i) == '*') {
        while (  (p('*') <= p(t)) && (t  != '(')  && (!temp.equals("") )  ){ 
            postfix = postfix + temp.charAt(i);
    }}     
      ***if (infix.charAt(i) == '/') {
        while (  (p('/') <= p(t)) && (t  != '(')  && (!temp.equals("") )  ){ 
            postfix = postfix + temp.charAt(i);
   }}    

      if (infix.charAt(i) == '(') {
        temp = infix.charAt(i)+temp;
   }

    if (infix.charAt(i) == ')') {
        infix = temp;***

        }

}


        return postfix;
}