Правильно ли составленно условие задачи?

package stopprog;
 
import java.util.Scanner;
 
public class Stopprog {
    public static void main(String[] args) {
        String answer;
        Scanner s = new Scanner(System.in);
        do {
            System.out.println("Stop program? (yes/no)?");
            answer = s.nextLine();
            if (!(answer.equals("yes"))) {System.out.println("Program is working now...");}
        } while (!(answer.equals("yes")));
        System.out.println("Program is stopped!");
    }
}

package cyberforum;
 
import java.util.Scanner;
 
public class stopProgramm {
 
    public static void main(String[] args) {
        String y = "yes";
        String enter = null;
        
        do {
            System.out.println("Stop programm? Enter Yes or No");
            enter = new Scanner(System.in).next();
        } while (!y.equalsIgnoreCase(enter));
        System.out.println("Programm stopped.");
    }
}

    public static void main(String[] args) {
        String enter;
        do {
            System.out.println("Stop program? Enter 'yes' or 'no'");
            enter = new Scanner(System.in).next().intern();
        } while (enter != "yes");
        System.out.println("Program stopped.");
    }