Doubt with decision making

Question

My dears, I have the following code:

  public static void questionTwo(){
    String back = "";
    Scanner scan = new Scanner(System.in);

    System.out.println("Questao 02: ");

    while(!back.equalsIgnoreCase("N") && !back.equalsIgnoreCase("NO")){
      System.out.println("TO DO");

      System.out.println("Deseja executar essa questao novamente? [Y/YES || N/NO]");
      back = scan.next();
    }
  }

So far it works OK, assuming the user is not a retard. But let’s assume he is and type something other than Y/YES or N/NO

How do I return to the System.out.println("Deseja executar essa questao novamente? [Y/YES || N/NO]"); if he enters something other than what was proposed without repeating what is before that within the while?

Answer 1

Try it like this:

private static boolean estaDentro(String resposta, String... alternativas) {
    return Arrays.asList(alternativas).contains(resposta.toUpperCase(Locale.ROOT));
}

public static void questionTwo() {
    Scanner scan = new Scanner(System.in);

    repeteQuestao: while (true) {
        System.out.println("Questao 02: ");
        System.out.println("TO DO");

        while (true) {
            System.out.println("Deseja executar essa questao novamente? [Y/YES || N/NO]");
            String digitado = scan.nextLine();
            if (estaDentro(digitado, "N", "NO")) break repeteQuestao;
            if (estaDentro(digitado, "Y", "YES")) continue repeteQuestao;
            System.out.println("Não entendi o que você quis dizer, tente novamente.");
        }
    }
}

Put also, these two Imports in the beginning:

import java.util.Arrays;
import java.util.Locale;

The method estaDentro checks whether the string of the first parameter (resposta) is one of the past alternatives.

We have two whiles. The only way out of the while external (called the repeteQuestao) is to answer N or NO, what will make a break in this loop is executed. If the user responds Y or YES, the continue in the external loop will be executed, which will cause the question to be repeated. Any other answer will make the Deseja executar essa questao novamente? be repeated as many times as necessary without the entire question being displayed until the user is no longer delayed (according to its definition).

The trick is I’m naming the ribbon while external to be able to refer to it in a break or continue later. This is a feature of the Java language that few people know, but which is very useful in situations like this.