Java Input Needed Twice - 我解析了一个整数所以我可以使用scanner.next();

Question

public static void main(String[] args) {

    Scanner scanner = new Scanner(System.in);

    // printing menu 
    System.out.println(menu);
    boolean quit = false;
    int selection;
    do {
        // next user input (of integer type) will be stored in the variable selection
        selection = Integer.parseInt(scanner.next());
        switch (selection) {
            case 1:
                System.out.println("Please enter a new record as John Michael West Doe, 574 Pole ave, St. Peter, MO, 63303, 3142752000");

                scanner.useDelimiter(",");

                Person[] people = new Person[0];

                while (scanner.hasNext()) {
                    String fullName = scanner.next();
                    String street = scanner.next();
                    String city = scanner.next();
                    String state = scanner.next();
                    String zipC = scanner.next();
                    String phoneN = scanner.next();

                    System.out.println(fullName);
                }

                break;
            case 2:
                // method to delete record - remove 
                break;
            case 3:
                // search by telephone number
                break;
            case 4:
                // find record by first name
                break;
            case 5:
                // find record by last name
                break;
            case 6:
                // update a record 
                break;
            case 7:
                quit = true;
                break;
            default:
                System.out.println("Invalid");
        }
    } while (selection != 7);
}

Hi, I'm currently working on case 1 - my problem is that I have to input the code twice for it to accept it and print out the fullName string..

Even at the beginning, when I make a selection and press 1 and enter, I have to type another key before the 'please enter a new record.....' line pops up.

I had just learned about what nextInt does and how it leaves a new line, so I parsed it in order to use scanner.next();

I'm just trying to see where the hang up is.

Thank you.

Answer 1

There is zero difference between scanner.nextInt() and Integer.parseInt(scanner.next()) , except for the kinds of errors that are thrown if the next token in the input stream isn't an integer. You must have misunderstood a few things.

I pasted your code into a file, compiled it, ran it, and cannot reproduce your observed behaviour of 'I have to press enter twice'. I just press enter once, and Please enter... shows.

There is nothing wrong with your code. At least, nothing that would explain why you need to double-enter here.