Do you know why my java calculator isn't working

package calculator;
import java.util.Scanner;

public class Calculator {
    
    
    
    public static void main(String[] args) {
        
        String operator;
        
        System.out.println("Would you like to add, subtract, multiply, or divide");
        Scanner choiceOP = new Scanner(System.in);
        String choice = choiceOP.nextLine();
        
        //for a testing purpose... delete after completion
        System.out.println(choice);
        
        methods method = new methods();
        
        if (choice == "add"){
            operator = "add";
            
            System.out.println("Choose your first number to " + operator);
            Scanner numScan = new Scanner(System.in);
            int num1 = numScan.nextInt();
            System.out.println("Choose your second number to " + operator);
            Scanner numScan2 = new Scanner(System.in);
            int num2 = numScan.nextInt();
            
            method.add(num1, num2);
        } else if (choice == "subtract"){
            operator = "subtract";
            
            System.out.println("Choose your first number to " + operator);
            Scanner numScan = new Scanner(System.in);
            int num1 = numScan.nextInt();
            System.out.println("Choose your second number to " + operator);
            Scanner numScan2 = new Scanner(System.in);
            int num2 = numScan.nextInt();
            
            method.subtract(num1, num2);
        } else if (choice == "multiply"){
            operator = "multiply";
            
            System.out.println("Choose your first number to " + operator);
            Scanner numScan = new Scanner(System.in);
            int num1 = numScan.nextInt();
            System.out.println("Choose your second number to " + operator);
            Scanner numScan2 = new Scanner(System.in);
            int num2 = numScan.nextInt();
            
            method.multiply(num1, num2);
        } else if (choice == "divide"){
            operator = "divide";
            
            System.out.println("Choose your first number to " + operator);
            Scanner numScan = new Scanner(System.in);
            int num1 = numScan.nextInt();
            System.out.println("Choose your second number to " + operator);
            Scanner numScan2 = new Scanner(System.in);
            int num2 = numScan.nextInt();
            
            method.divide(num1, num2);
        } else{
            System.out.println("That is not a correct operator");
        }
        
    }
}

package calculator;

public class methods {
    
    public void add(int num1, int num2){
        double answer = num1 + num2;
        System.out.println("The answer is " + answer);
    }
    public void subtract(int num1, int num2){
        double answer = num1 - num2;
        System.out.println("The answer is " + answer);
    }
    public void multiply(int num1, int num2){
        double answer = num1 * num2;
        System.out.println("The answer is " + answer);
    }
    public void divide(int num1, int num2){
        double answer = num1 / num2;
        System.out.println("The answer is " + answer);
    }
    
}