How to do, Do while loop for this code?

Question

I have this java code:

public class Ages {
public static void main(String[] args) {
    Scanner keyboard = new Scanner(System.in);  

    int value = 0;
    String name;
    int age;



        System.out.print("Hey, what's your name? ");
        name = keyboard.next();
        System.out.println();

        System.out.print("Ok, " + name + ", how old are you? ");
        age = keyboard.nextInt();
        System.out.println();

           do{
            if(age < 16){
            System.out.println("You can't visit in the museum, " + name + ".");

            if(age < 18);
                 System.out.println("You can't visit in the park, " + name + ".");
            }
            if (age < 25){
                System.out.println("You can't visit if you have a car, " + name + ".");
            }
            if (age >= 25){
                System.out.println("You can do anything, " + 
                    name + ".");

            }
            while(age > 300);
            System.out.println("It's not correct..Try Again, " + name + 
             ".");


            }
}

and I need that user write the wrong answer, he will get the question again "how old are you?", and after he get another tries.. what I goona do? Thanks for the help!! :)

Answer 1

1)You should use this condition : if (age >= 25 && age <= 300){ instead of if (age >= 25){.

Otherwise the condition is true even if age is over 300 and you don't want to:

while(age > 300);

2)You should also allow the user to enter a new input if the value is not correct.

age = keyboard.nextInt(); should be in the loop.

3) You should allow the loop to finish.
In the while statement, you could specify the condition that requires a new input from the user :

while (age > 300)

This gives the code (not tested) :

  int age;
  do{
    age = keyboard.nextInt();

    if(age < 16){
        System.out.println("You can't visit in the museum, " + name + ".");
    }
    else if(age < 18){
         System.out.println("You can't visit in the park, " + name + ".");
    }
    else if (age < 25){
        System.out.println("You can't visit if you have a car, " + name + ".");
    }

    if (age >= 25 && age <= 300){
        System.out.println("You can do anything, " + 
            name + ".");                
    }
    else{
        System.out.println("It's not correct..Try Again, " + name +  ".");
    }
  }                 
  while (age > 300);

Answer 2

One the while block is not correct you have to use :

System.out.println("It's not correct..Try Again, " + name + ".");

do {
    if (age < 16) {
        System.out.println("You can't visit in the museum, " + name + ".");

        if (age < 18);
        System.out.println("You can't visit in the park, " + name + ".");
    }
    if (age < 25) {
        System.out.println("You can't visit if you have a car, " + name + ".");
    }
    if (age >= 25) {
        System.out.println("You can do anything, "
                + name + ".");

    }
    //while(age > 300);<<----------wrong position 

    System.out.println("It's not correct..Try Again, " + name + ".");

} while (age > 300);//<<----------correct position 

Two

The while condition seams not correct, you have to check with min and max age, instead of just max, so you can use :

 while (age < minAge || age > maxAge );

So if the age is less then the min OR great then the max repeat again

Three this if will not ever executed :

if (age < 18);//<<----------------note the ; it mean your if is end
    System.out.println("You can't visit in the park, " + name + ".");

Four

Instead you can read the age inside your loop :

System.out.print("Hey, what's your name? ");
name = keyboard.next();
System.out.println();

do {

    System.out.print("Ok, " + name + ", how old are you? ");
    age = keyboard.nextInt();
    System.out.println();
    ....
}while(..);

---

Hope this can gives you an idea about your problem.

Answer 3

Try this, please:

public class Ages {
    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);

        int value = 0;
        int age;

        System.out.print("Hey, what's your name? ");
        String name = keyboard.next();
        System.out.println();

        while(true) {
            System.out.print("Ok, " + name + ", how old are you? ");
            age = keyboard.nextInt();
            System.out.println();
            if (age <= 300) {
                break;
            }
            System.out.println("It's not correct..Try Again, " + name +
            ".");
        }

        if(age < 16) {
            System.out.println("You can't visit in the museum, " + name + ".");
        }
        if(age < 18){
            System.out.println("You can't visit in the park, " + name + ".");
        }
        if (age < 25){
            System.out.println("You can't visit if you have a car, " + name + ".");
        }
        if (age >= 25){
            System.out.println("You can do anything, " +
                name + ".");

        }
    }
}