Day 12 calcu More

package week2;

import java.util.Scanner;
public class Day12B {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double num1=0, num2=0, result;
        String userInput, op = "";
        String[] opList = {"+","-","*","/","^"};
        boolean isValid = false;

//        while (!isValid) {
        while (isValid == false) {
            System.out.print("Enter num A: ");
            userInput = sc.nextLine();
            isValid = isNumeric(userInput);
            if (isValid == true) {
                num1 = Double.parseDouble(userInput);
            } else {
                System.out.println("please try again");
            }
        }
        isValid = false;
        while (isValid == false) {
            System.out.print("Enter operation(+,-,*,/,^): ");
            userInput = sc.nextLine();
            for (String string : opList) {
                if (userInput.equals(string)) {
                    isValid = true;
                }
            }
            if (isValid == true) {
                op = userInput;
            } else {
                System.out.println("please try again");
            }
        }
        isValid = false;
        while (isValid == false) {
            System.out.print("Enter num B: ");
            userInput = sc.nextLine();
            isValid = isNumeric(userInput);
            if (isValid == true) {
                num2 = Double.parseDouble(userInput);
            } else {
                System.out.println("please try again");
            }
        }
        result = compute(num1, num2, op);
        System.out.printf("%.2f %s %.2f = %.2f %n", num1, op, num2, result);
    }

    static boolean isNumeric(String txtIn) {
        boolean isNumber = true;
        if (txtIn.trim().isEmpty()) {
            isNumber = false;
        }
        try {
            double d = Double.parseDouble(txtIn);
        } catch (Exception e) {
            isNumber = false;
        }
        return isNumber;
    }

    static double compute(double num1, double num2, String op){
        double result;
        switch (op) {
            case "+" :
                result = num1 + num2;
                break;
            case "-" :
                result = num1 - num2;
                break;
            case "*" :
                result = num1 * num2;
                break;
            case "/" :
                if (num2 > 0) {
                    result = num1 / num2;
                } else {
                    System.out.println("cannot divide by zero");
                    result = 0;
                }
                break;
            case "^" :
                result = Math.pow(num1, num2);
                break;
            default:
                result = 0;
        }
        return result;
    }
}
//----- ------------ ------- ----- --
package week2;

abstract class Day12CalcuAbstract {
    abstract double enterNumber();
    abstract String enterOperator();

    static boolean isNumeric(String txtIn) {
        boolean isNumber = true;
        if (txtIn.trim().isEmpty()) {
            isNumber = false;
        }
        try {
            double d = Double.parseDouble(txtIn);
        } catch (Exception e) {
            isNumber = false;
        }
        return isNumber;
    }

    static double compute(double num1, double num2, String op){
        double result;
        switch (op) {
            case "+" :
                result = num1 + num2;
                break;
            case "-" :
                result = num1 - num2;
                break;
            case "*" :
                result = num1 * num2;
                break;
            case "/" :
                if (num2 > 0) {
                    result = num1 / num2;
                } else {
                    System.out.println("cannot divide by zero");
                    result = 0;
                }
                break;
            case "^" :
                result = Math.pow(num1, num2);
                break;
            default:
                result = 0;
        }
        return result;
    }
}

//-------------- ------- ------- ----- ------
package week2;

import java.util.Scanner;
public class Day12D extends Day12CalcuAbstract{
    Scanner sc = new Scanner(System.in);
    String userInput = "";
    String[] opList = {"+","-","*","/","^","x"};

    public static void main(String[] args) {
        Day12D callMe = new Day12D();
        double num1=0, num2=0, result;
        String op = "";

        System.out.println("type x for operator to end");
        num1 = callMe.enterNumber();
        while (!op.equalsIgnoreCase("x")) {
            op = callMe.enterOperator();
            if (op.equalsIgnoreCase("x")) {
                break;
            }
            num2 = callMe.enterNumber();
            if (!op.equalsIgnoreCase("x")) {
                result = compute(num1, num2, op);
                System.out.printf("%.2f %s %.2f = %.2f %n", num1, op, num2, result);
                num1 = result;
            }
        }
    }

    double enterNumber(){
        double numOut = 0;
        boolean isValid = false;
        while (isValid == false) {
            System.out.print("Enter number: ");
            userInput = sc.nextLine();
            isValid = isNumeric(userInput);
            if (isValid == true) {
                numOut = Double.parseDouble(userInput);
            } else {
                System.out.println("please try again");
            }
        }
        return numOut;
    }

    String enterOperator(){
        String opr = "X";
        boolean isValid = false;
        while (isValid == false) {
            System.out.print("Enter operation(+,-,*,/,^): ");
            userInput = sc.nextLine();
            for (String string : opList) {
                if (userInput.equalsIgnoreCase(string)) {
                    isValid = true;
                }
            }
            if (isValid == true) {
                opr = userInput;
            } else {
                System.out.println("please try again");
            }
        }
        return opr;
    }
}