Why is my program entering a while loop when the condition is false?

When I input a string operator whether it be addition(+), subtraction(-), multiplication(*), division(/) or module(%), it still enters the while loop even when I enter a valid input. I don't know what the problem could be because the while loop is working fine where I have to enter an int-value for variable num2.

import java.util.Scanner;

public class PolishNotationCalc {

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);
        int num1;
        int num2;
        String operator;

        System.out.println("Polish notation calculator");

        System.out.print("Please enter an operation(+, -, *, /, %) ");
        operator = input.nextLine();

        while (!operator.equals("+") || !operator.equals("-") || !operator.equals("*") || !operator.equals("/") || !operator.equals("%")) {
            System.out.println("Please enter a valid operation ");
            operator = input.nextLine();
            if (operator.equals("+") || operator.equals("-") || operator.equals("*") || operator.equals("/") || operator.equals("%"))
                break;
        }

        System.out.print("");
        System.out.print("Please enter the first number ");
        num1 = input.nextInt();

        System.out.print("Please enter the second number ");
        num2 = input.nextInt();

        while (num2 == 0 && operator.equals("/")) {
            System.out.println("Please pick a non zero number: ");
            num2 = input.nextInt();
        }
        while (num2 == 0 && operator.equals("%")) {
            System.out.println("Please pick a non zero number: ");
            num2 = input.nextInt();

        }

        if (operator.equals("+"))
            System.out.println(num1 + " + " + num2 + " = " + (num1 + num2));

        else if (operator.equals("-"))
            System.out.println(num1 + " - " + num2 + " = " + (num1 - num2));

        else if (operator.equals("*"))
            System.out.println(num1 + " * " + +num2 + " = " + (num1 * num2));

        else if (operator.equals("/"))
            System.out.println(num1 + " / " + num2 + " = " + (num1 / num2));

        else if (operator.equals("%"))
            System.out.println(num1 + " % " + num2 + " = " + (num1 % num2));

    }

}