OOP 1 - Using STATIC Classes

Firstly, set up a new package called OOP1_Calculator.

Your job is to create 2 new classes in your OOP1_Calculator package.  One will be a Java Main Class.  The other just a java class.:

• OOP1CalculatorMain
• OOP1CalculatorMethods

OOP1CalculatorMethods

STATIC classes are designed with useful methods but are not ever going to be instantiated.  This will be one such static (methods only) class.  Your goal is to create 6 methods that do simple calculations.  The logic is meant to be easy.  The result will be that you will be comfortable with the concepts before we move onto more complex OOP.

Each method must:

• Ask the user for the numbers needed.  You may use Println and Scanner or the Input class
• Calculate the result
• RETURN the result to main.  Do not print the answer here.  Return the answer to MAIN.  (No printlns should be used here except for debugging purposes.) 

Suggestions are:

• The 4 basic operations (add, subtract, etc.)
• Calculate C in Pythagoras’ equation
• Raise one number to the power of another

OOP1CalculatorMain

This will contain the main method.  In it you should build a menu for the user that you will add to as the assignment progresses.  Start by just setting up a loop that continues until the user says “exit”.

Eventually, the menu should:

• Print the list of calculation options.
• Ask for their choice
• Call the appropriate method from the other class
• Print the result returned
• Loop until they say exit for their choice

Evaluation:

• Required methods, properly used                        50%
• Menu and loop                                         30%
• User friendliness                                        10%
• Good Coding (indenting and commenting)                10%

OLD & BAD Instructions are Below

Last year (or earlier this year) you created a simple calculator as an introduction to passing parameters to methods. One version of this old assignment is copied on the next page of this document.  Read through the code on the next pages to remind yourself how it was written.   You are allowed to copy and paste whatever you want from this original code.

Ignore for 2015/16 - Note: the last 10% of many assignments in this credit is to make a GUI based version of the assignment.  For this assignment, I will allow Pop Ups (JOptionPane) to count as GUI.

Your job is to create 2 new classes.  One will be a Java Main Class.  The other just a java class.:

• OOP1CalculatorMain
• OOP1CalculatorMethods

OOP1CalculatorMain

This will contain the main method.  In it you should build a menu for the user that you will add to as the assignment progresses.  Start by just setting up a loop that continues until the user says “exit”.

Eventually, the menu should:

• allow the user to choose from the calculations in the OOP1CalculatorMethods class described below.  (add them one at a time as per the instructions below)
• asks for necessary info, calls the method and prints the result.  Everything should be printed by the OOP1CalculatorMain class.  No printlns should appear in the other class.
• loop until the user chooses to exit

OOP1CalculatorMethods

This will be a methods only class.  Your goal is to create 5 methods that simplify calculations. Some of the methods described are actually available in some form in the Math class but your job is to recreate them.

Note: No printlns should be used in this class.  All methods should RETURN their answer.

1. Begin by copying and pasting the doMath() method (highlighted section) from the next pages of this document. This method does the adding, subtracting, multiplying and dividing so add these choices to the main menu.  
2. Add a pythagorean method that takes in a and b and returns c.  Add it to the choices in main and test before continuing.  Hint:there is a Math.sqrt() function.
3. Add a power method that takes in two parameters so that the first is raised to the power of the second.  This can be done in a for loop OR using the Math.pow() method.  Ask for help if  you need it as the coding of this is not the real goal of the assignment.
4. Your choice - keep it simple (5ish lines of code or less)
5. Your choice - keep it simple (5ish lines of code or less)

Code based on a Grade 11 Simple Calculator Assignment

import java.util.Scanner;

public class OOP1CalculatorMain {

    //Global Variables

    static Scanner numscan = new Scanner(System.in);

    static Scanner wordscan = new Scanner(System.in);

    public static void main(String[] args) {

        System.out.println("Welcome to the calculator.");

        String choice;

        while (true) {

       System.out.println("Please make a choice from the following list.");

System.out.println("Do Simple Math - please type math");

System.out.println("Find C in a Pythagorus Triangle = please type find c");

System.out.println("Find a number raised to the power of another - please type power");

System.out.println("????? - please type ?????");

System.out.println("?????? - please type ????");

System.out.println("To exit - please type exit");

System.out.println("Enter your choice now.");

       choice = wordscan.nextLine().toLowerCase();

       if(choice.equals("exit")) {

                return;

}

       if(choice.equals(“math”){        

                        System.out.println("Enter your operator (+, -, *, /)");

String operator = wordscan.nextLine();

System.out.println("Enter first number:");

                        double num1 = numscan.nextDouble();

                        System.out.println("Enter second number:");

                       double num2 = numscan.nextDouble();

                        //the next line needs to be tweaked to work with OOP

System.out.println("The answer is " + OOP1Calculator.doMath(operator, num1, num2);

       } else if (choice.equals(“find c”){

System.out.println("For your triangle, enter the length of A.");

                        double num1 = numscan.nextDouble();

System.out.println("Now enter the length of B.");

                        double num2 = numscan.nextDouble();

//the next line needs to be tweaked to work with OOP

                        System.out.println("The length of c is " + OOP1Calculator.pythagorus(num1, num2);

}  

//need to add power() and the other two option      

        }//End While

    }//End Main

}//end OOP1CalculatorMain

public class OOP1Calculator{

    public static double doMath(String op, double n1, double n2) {

        if(op.equals("+")) {

            return n1+n2;

        } else if(op.equals("-")) {

            return n1-n2;

        } else if(op.equals("*")) {

            return n1*n2;

        } else if(op.equals("/")) {

            return n1/n2;

        } else {

            return 0;//This is for debugging purposes

        }          

    }//End doMath

  public static double pythagorus (int a, int b){

         int c = 0;

         return c;

     }

     public static int power(int num, int exponent){

         int total = 0;

         return total;

     }

}//End OOP1Calculator Class