循环执行3次

Question

I am working on a school exercise that asks me to modify the .java code so that the user is asked to input the right number only 3 times.

The code I get is this:

    public static void main (String[] args) {
        Scanner lector = new Scanner(System.in);
        int valorUsuari = 0;
        boolean valorNOk=true;
        while (valorNOk){
            System.out.print("Insert a number between 0 and 5: ");
            valorUsuari = lector.nextInt();
            lector.nextLine();
            if((valorUsuari >= 0)&&(valorUsuari <= 5)){
              valorNOk=false;    
            }
        }
        System.out.println("Data correct. You typed " + valorUsuari);
    }
}

I tried doing this before the while condition and it doesn't seem to work:

for (valorUsuari = 0; valorUsuari <= 3 ; valorUsuari++)

Do you have any idea where I am going wrong?

Thank you in advance!

Answer 1

Just add a counter that starts at 0 and when it hits 3, the user is no longer allowed to enter a number. Every time the users writes something illegal, add one to the counter.

public static void main (String[] args) {
    Scanner lector = new Scanner(System.in);
    int valorUsuari = 0;
    int counter = 0; //this is your counter, it starts at 0 because the user has failed 0 times at this point
    boolean valorNOk=true;
    while (valorNOk && counter < 3){
        System.out.print("Insert a number between 0 and 5: ");
        valorUsuari = lector.nextInt();
        lector.nextLine();
        if((valorUsuari >= 0)&&(valorUsuari <= 5)){
          valorNOk=false;    
        } else {
            counter++; //this is added to keep track of failed tries
        }
    }
    System.out.println("Data correct. You typed " + valorUsuari);
}

Note: This isn't really relevant for you at this point, but your valorNOk is pretty redundant. You can simply use break instead like this:

public static void main (String[] args) {
    Scanner lector = new Scanner(System.in);
    int valorUsuari = 0;
    int counter = 0; //this is your counter, it starts at 0 because the user has failed 0 times at this point
    while (counter < 3){
        System.out.print("Insert a number between 0 and 5: ");
        valorUsuari = lector.nextInt();
        lector.nextLine();
        if((valorUsuari >= 0)&&(valorUsuari <= 5)){
            break; 
        } else {
            counter++; //this is added to keep track of failed tries
        }
    }
    System.out.println("Data correct. You typed " + valorUsuari);
}

Another note: Even if the user inputs wrongly three times, you will still print "Data correct..." . What you could do is something like this after your while-loop:

if(counter < 3) {
    System.out.println("Data correct. You typed " + valorUsari);
} else {
    System.out.println("Too many tries. You are bad.");
}

Answer 2

Modified it a bit, I used a counter int tries to keep track of the tries.

 public static void main(String[] args) throws Exception {
        Scanner lector = new Scanner(System.in);
        int valorUsuari = 0;
        boolean valorNOk = true;
        int tries = 0;
        while (valorNOk && tries < 3) {
            System.out.print("Insert a number between 0 and 5: ");
            valorUsuari = lector.nextInt();
            lector.nextLine();
           if ((valorUsuari >= 0) && (valorUsuari <= 5)) {
            valorNOk = false;
        } else {
            tries++;
        }
        System.out.println("Data correct. You typed " + valorUsuari);
    }