Ignore UpperCase

Method 1: use “(?!)”

if (scan.hasNext("(?i)bye")){
    scan.hasNext();
    System.out.println("You entered 'bye', program ended. Goodbye!");
    return;
}

Method 2: Convert to lowercase

String input = scan.next().trim().toLowerCase();
      if (input.equals("bye")) {
      System.out.println("You entered 'bye', program ended. Goodbye!");
      return;
}

Method 3: Ignore it

if (scan.hasNext()){
   String input = scan.next.().trim.();
   if(input.equalsIgnoreCase("bye")){
     System.out.println("You entered 'bye', program ended. Goodbye!");
      return;
   }
}