RPN (Reverse Polish Notation) is a postfix method of expression mathem functions.

Read all of the directions in the attached picture

AnsweAnyPartYouCan

UseAll8ClassesBelowToStartThis

package cs232.RPNCalc;

import java.util.ArrayList;

public interface RPNStringTokenizer {
    public static ArrayList<String> tokenize (String expression) {
        // take a string.  If it is valid RPN stuff - integers or operators
        // - then put them in a list for processing.
        // anything bad (not int or one of the operators we like) and return a null.

        // YOU WRITE THIS!
        return null;
        
    }
}

package cs232.RPNCalc;

import java.util.ArrayList;

public class RPNTester {

    public static void main(String[] args) {
        // don't change this method!
        YourRPNCalculator calc = new YourRPNCalculator(new YourArrayListStack());
        System.out.println("Testing ArrayList version");
        testRPNCalculator(calc);
        
        calc = new YourRPNCalculator(new YourLinkedListStack());
        System.out.println("Testing LinkedList version");
        testRPNCalculator(calc);
    }
    
    private static void testRPNCalculator(SimpleRPNCalculator calc) {
        ArrayList<String> testExpressions = new ArrayList<>();
        testExpressions.add("1 1 +"); // 2
        testExpressions.add("1 3 -"); // 2
        testExpressions.add("1 1 + 2 *"); // 4
        testExpressions.add("1 1 2 + *"); // 3
        testExpressions.add("1 1 + 2 2 * -"); // 2
        testExpressions.add("11 bv +"); // bad token
        testExpressions.add("2 3 + -"); // underflow on an operator
        testExpressions.add("2 3 + 4 5 -"); // leftover tokens
        // YOU SHOULD ADD MORE TEST CASES!
        
        for (String s : testExpressions) {
            System.out.println(calc.calculate(s));
        }
        
    }

}

package cs232.RPNCalc;

public interface SimpleRPNCalculator {
    public String calculate(String inputString);
    
    /*
     * RPN (Reverse Polish Notation) is a postfix method of expression mathematical functions.
     * It is traditionally used to eliminate the necessity of parenthesis by removing the
     * order of operations and acting on operators as they occur.
     * 
     * Very simply, INFIX notation "1 + 1" is represented in POSTFIX notation as "1 1 +"
     * Longer expressions may change radically.  "1 + 2 * 3" assumes an order of operations, 
     * while in POSTFIX, "2 3 * 1 +" or "1 2 3 * +"
     * 
     * The calculator works as follows:
     * if number, push to a stack
     * if operator, pop two numbers, operate on them, and push the result
     * if I hit an operator and there are not two numbers on the stack, it's a bad expression
     * if I get to the end of the expression and there is not exactly one number on the stack,
     *    it's a bad expression.
     *    
     * Making something that looks like it works - the input to output happening without a crash
     * Implement LinkedListBasedStack
     * Implement ArrayList
     * 
     * YOUR CALCULATOR ONLY NEEDS TO WORK FOR +, -, and *
     * YOUR CALCULATOR NEEDS TO WORK ON INTEGERS.
     * 
     * Has to work on Doubles (this is a gimme)
     * Bonus points for implementing division / (this is deceptively hard, DO THIS LAST!)
     * 
     * 
     */

}

package cs232.RPNCalc;

public interface TGStack {
    public void push (Integer i);
    public Integer pop();
    public Integer size();
}

package cs232.RPNCalc;

import java.util.ArrayList;

public class YourArrayListStack implements TGStack {
    // YOU MUST USE THIS IMPLEMENTATION - just code the methods
    ArrayList<Integer> theStack = new ArrayList<>();

    @Override
    public void push(Integer i) {

    }

    @Override
    public Integer pop() {
        return null;
    }

    @Override
    public Integer size() {
        return null;
    }

}

package cs232.RPNCalc;

public class YourLinkedListStack implements TGStack {
    // YOU MUST USE THIS IMPLEMENTATION - just code the methods
    private YourStackNode head = null;
    private Integer size = 0;
    
    @Override
    public void push(Integer i) {
        
    }

    @Override
    public Integer pop() {
        return null;
    }

    @Override
    public Integer size() {
        return null;
    }

}

package cs232.RPNCalc;

import java.util.ArrayList;

public class YourRPNCalculator implements SimpleRPNCalculator {
    // don't change these...
    TGStack theStack = null;
    
    public YourRPNCalculator(TGStack stack) {
        theStack = stack;
    }

    
    @Override
    public String calculate(String inputString) {
        // this is probably helpful, but you can remove...
        ArrayList<String> tokens = RPNStringTokenizer.tokenize(inputString);
        
        // here's the calculator logic!
        return null;
        
    }

}

package cs232.RPNCalc;

public class YourStackNode {
    // DO NOT CHANGE THIS!
    private Integer item;
    private YourStackNode next;
    
    public Integer getItem() {
        return item;
    }
    
    public YourStackNode getNext() {
        return next;
    }
    
    public void setItem (Integer i) {
        item = i;
    }
    
    public void setNext (YourStackNode node) {
        next = node;
    }

}