The Adding Calculator

package theaddingcalculator;

import java.util.Scanner;

public class Addingcalculator {
    private int number1;
    private int number2;
    private char operation;

    Addingcalculator(int number1, char operation, int number2) {
        this.number1 = number1;
        this.number2 = number2;
        this.operation = operation;
    }

    Addingcalculator() {
        Scanner scan = new Scanner(System.in);
        System.out.println("Write operation: ");
        String separatedInput = separateAddingCalculatorInput(scan.nextLine());
        this.number1 = Integer.valueOf(separatedInput.substring(0, separatedInput.indexOf(' ')));
        this.operation = separatedInput.charAt(separatedInput.indexOf(' ') + 1);
        this.number2 = Integer.valueOf(separatedInput.substring(separatedInput.lastIndexOf(' ') + 1));
    }

    private String separateAddingCalculatorInput(String scanLine) {
        String separatedLine = "";
        boolean sign = false;
        separatedLine += scanLine.charAt(0);
        for (int i = 1; i < scanLine.length(); i++) {
            if (sign == false && (scanLine.charAt(i) == '+' || scanLine.charAt(i) == '-' || scanLine.charAt(i) == '*'
                    || scanLine.charAt(i) == '/' || scanLine.charAt(i) == '^')) {
                separatedLine += " " + scanLine.charAt(i) + " ";
                sign = true;
            } else if (sign == false && scanLine.charAt(i) != ' ') {
                separatedLine += scanLine.charAt(i);
            } else if (sign == true && scanLine.charAt(i) != ' ') {
                separatedLine += scanLine.charAt(i);
            }

        }
        return separatedLine;
    }

    private int negate(int number) {
        int negateNumber = Integer.MIN_VALUE;
        while (number + negateNumber != 0) {
            negateNumber++;
        }
        return negateNumber;
    }

    private int adding() {
        return this.number1 + this.number2;
    }

    private int subtraction() {
        return this.number1 + negate(this.number2);
    }

    private int multiply() {
        int result = 0;
        int signNumber1 = 0;
        int signNumber2 = 0;
        if (this.number2 < 0) {
            signNumber2 = negate(this.number2);
        } else {
            signNumber2 = this.number2;
        }
        if (this.number1 < 0) {
            signNumber1 = negate(this.number1);
        } else {
            signNumber1 = this.number1;
        }
        for (int i = 0; i < signNumber2; i++) {
            result += signNumber1;
            ;
        }
        if (multiplySignChecker())
            return result;
        else
            return negate(result);

    }

    private boolean multiplySignChecker() {
        if ((this.number1 > 0 && this.number2 > 0) || (this.number1 < 0 && this.number2 < 0)) {
            return true;
        } else {
            return false;
        }
    }

    private boolean divideIntegerResultChecker() {
        if ((this.number1 > 0 && this.number1 < this.number2)
                || (this.number1 < 0 && negate(this.number1) < this.number2)) {
            System.out.println("Non-integral answer");
            return false;
        } else if (this.number1 == 0 && this.number2 == 0) {
            System.out.println("Not-defined");
            return false;
        } else if (this.number2 == 0) {
            System.out.println("Divide by 0 error!");
            return false;

        } else {
            if ((this.number1 > 0 && divide()[0] == this.number1)
                    || (this.number1 < 0 && divide()[0] == negate(this.number1)))
                return true;
            else
                System.out.println("Non-integral answer");
            return false;
        }

    }

    private int[] divide() {
        int[] helper = new int[2]; //idk how to return two int so i do this kind of darkmagic
        int signNumber1 = 0;
        int signNumber2 = 0;
        if (this.number2 < 0) {
            signNumber2 = negate(this.number2);
        } else {
            signNumber2 = this.number2;
        }
        if (this.number1 < 0) {
            signNumber1 = negate(this.number1);
        } else {
            signNumber1 = this.number1;
        }
        while (helper[0] < signNumber1) {
            helper[0] += signNumber2;
            helper[1]++;
        }
        if (!multiplySignChecker())
            helper[1] = negate(helper[1]);

        return helper;
    }

    private boolean exponentationIntegerResultChecker() {
        if (this.number2 < 0) {
            System.out.println("Non-integral answer");
            return false;
        } else {
            return true;
        }
    }

    private int exponentation() {
        int result;
        int signNumber1 = 0;
        if (this.number2 == 0) {
            result = 1;
        } else {
            if (this.number1 < 0) {
                signNumber1 = negate(this.number1);
            } else {
                signNumber1 = this.number1;
            }
            result = signNumber1;
            int multiplier = 0;
            for (int i = 1; i < this.number2; i++) {
                for (int j = 0; j < signNumber1; j++) {
                    multiplier += result;
                }
                result = multiplier;
                multiplier = 0;
            }
        }
        if (evenExponentChecker() || this.number1 > 0)
            return result;
        else
            return negate(result);
    }

    public boolean evenExponentChecker() {
        int helper = 0;
        for (int i = 0; i <= this.number2; i += 2)

            helper = this.number2 + negate(i);

        if (helper == 0) {
            return true;
        } else {
            return false;
        }
    }

    public void signCollector() {
        int result = 0;
        boolean error = false;
        switch (this.operation) {
        case '+':
            result = adding();
            break;
        case '-':
            result = subtraction();
            break;
        case '*':
            result = multiply();
            break;
        case '/':
            if (divideIntegerResultChecker())
                result = divide()[1];
            else
                error = true;
            break;
        case '^':
            if (exponentationIntegerResultChecker())
                result = exponentation();
            else
                error = true;
            break;
        default:
            System.out.println("Sign of operation is not recognized");
            break;

        }
        if (!error)
            System.out.println(this.number1 + " " + this.operation + " " + this.number2 + " = " + result);
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Addingcalculator calc = new Addingcalculator();
        calc.signCollector();
        }


    }