AutoCalc by joshellis625

AutoCalc.java

import java.util.Scanner;

public class AutoCalc {

    /* It's conventional that field names are in camelCase, so I changed that.
     * 
     * The private keyword means only this class can look at these values. Here,
     * declaring the field as 'static' means that it's a class field, rather than
     * an instance field. The two x and y values are specific to one particular
     * instance of the calculator, rather than to the Calculator class a a whole,
     * and so are not supposed to be static.
     * 
     * I also deleted SUM, DIFF, etc. Think of these fields you define here not
     * as variables, but as properties that describe the state of your object.
     * The sum, diff, etc are not instrinsic parts of the object state, they're
     * calculated from x and y, which, in your case, are the actual 'state'
     * fields.
     */
    private int x, y;

    public static void main(String[] args) {
        /* We're going to create a calculator object, rather than having static
         * everything. 
         */
        AutoCalc calc = new AutoCalc();
        calc.run();

    }

    public void run() {
        /* I could've left all of this in main() and just called calc.getSum(), etc,
         * but I prefer it when tasks are divided a bit more finely. This way,
         * main() just worries about setting up the calc object and executing it
         * (allowing you to then make that setup more complex if it needs to be)
         * and the actual work is separated from the setup.
         */
        getInput();
        System.out.println();
        System.out.println("Let's do some math using the numbers " + x + " and " + y + "!");
        System.out.println();
        System.out.println("The sum of " + x + " and " + y + " is " + getSum());
        System.out.println("The difference between " + x + " and " + y + " is " + getDiff());
        System.out.println(x + " divided by " + y + " is " + getDivide());
        System.out.println(x + " times " + y + " is " + getMultiply());
    }

    public void getInput() {
        /* Not much to say here, this works well enough. */
        while (true) {
            try {

                Scanner input = new Scanner(System.in);

                //Apply String input to variables xString and yString
                System.out.print("Input first number: ");
                String X_STRING = input.next();
                System.out.print("Input second number: ");
                String Y_STRING = input.next();

                //Convert Strings to Integers
                x = Integer.parseInt(X_STRING);
                y = Integer.parseInt(Y_STRING);

                break;

            } catch (NumberFormatException nfe) {
                System.err.println("I said enter numbers...");
            }
        }
    }

    public int getSum() {
        /* The SUM, DIFF, etc fields you'd declared all the way up top weren't
         * really intrinsic parts of the object state, they were just variables
         * you needed as a way to get partial calculations done. What you could
         * have done is declare them locally to where you wanted to use them,
         * like this:
         */
        int sum = x + y;
        return sum;

    }

    public int getDiff() {
        /* But even then, those local variables aren't REALLY necessary, since
         * you're not doing anything too elaborate in these functions:
         */
        return x - y;

    }

    public float getDivide() {
        /* Though you might want to reintroduce them if things get more complex */
        float xf = (float) x,
                yf = (float) y;
        return xf / yf;

    }

    public int getMultiply() {
        return x * y;

    }
}