Reference no: EM13168445

 program below is suppose to take in a infix expression and translate it to a postfix expression, but I need a way for the user to be able to input the expression using a scanner and output the postfix. Can someone help me with this and make any changes to my program to make it work? Thank you! I know there is no main method, but that is what I need help writing to make it run properly.

import java.util.Scanner;
import java.util.Stack;


public class InfixToPostfix {
    
    private final char ADD = '+';
    /** constant for subtraction symbol */
    private final char SUBTRACT = '-';
    /** constant for multiplication symbol */
    private final char MULTIPLY = '*';
    /** constant for division symbol */
    private final char DIVIDE = '/';
    
    private Stack stack;
    public String expression;
    public char a;
    char top;
    String result = "";
    int value2;
    
    public InfixToPostfix(String b){
        expression = b;
        int sizeOfExpression = expression.length();
        stack = new Stack();
    }
    
    
    public String operator()
    {
        
        for (int i = 0; i < expression.length(); i++)
            a = expression.charAt(i);
        switch (a)
        {
        case ADD:
        onStack(a,1);
        break;
        
        case SUBTRACT:
        onStack(a,1);
        break;
        
        case MULTIPLY:
        onStack(a,2);
        break;
        
        case DIVIDE:
        onStack(a,2);
        
        default:
        result = result + a;
        break;
        }
    
        while (!stack.isEmpty())
        {
            result = result + stack.pop();
            
        }
        return result;
}
    public void onStack(char a, int value1)
    {
        while (!stack.isEmpty())
        {
            top = (char) stack.pop();
            
        
        if (top == '+' || top == '-')
            value2 = 1;
        else value2 = 2;
        if (value2 < value1)
        {stack.push(top);
                }
        else
            result = result + top;
        
        }


stack.push(a);
}

    
    
    


    
        // TODO Auto-generated method stub

    }