Question

What I’m trying to figure out is when user puts age < 18 I want program to stop. Same idea with “Jack” part below that If user named jack I want it to stop also.

import java.util.Scanner;

class Newbie
{
  public static void main(String[] arg)
  {
    Scanner qk = new Scanner(System.in);
    int age;
    String ans;

    System.out.println("How old are you?");
    age = qk.nextInt();

    if(age < 18)
      System.out.println(age + " is too young!");           

    if(age > 18)
      System.out.println("You can enter. What is your name?");

    Scanner q = new Scanner(System.in);
    ans = q.nextLine();

    if(ans.equals("Jack"))
    System.out.println("Jack, you are not allowed to use this program.");
  }
}

Answer 1

Consider using a boolean field to keep track of whether or not the user is authorized to use the program.

Example:

import java.util.Scanner;

class Newbie
{
    public static void main(String[] arg)
    {
      boolean authorized = true;
      Scanner qk = new Scanner(System.in);
      int Age;
      String ans;

      System.out.println("How old are you?");
      Age=qk.nextInt();
      in.nextLine(); // clear newline char from the buffer
      if(Age < 18) {
        System.out.println ( Age +" is too young! " ); 
        authorized = false;         
      }
      else { // else statement fixes logic error
        System.out.println ( " You can enter. What is your name ? " );
        ans=qk.nextLine();
        if (ans.equals("Jack")) {
          System.out.println ( "Jack, you are not allowed to use this program " );
          authorized = false;         
        }
      }
      if(authorized) {
        // Do program stuff here
      }
    }

}